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Event ID 538 Logon Type 3 NT AUTHORITY/ANONYMOUS LOGON

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Anonymous
a b 8 Security
March 10, 2005 2:29:14 PM

Archived from groups: microsoft.public.win2000.security (More info?)

The security event log on our W2K, SP4 server has hundreds of the above
messages in it. There are no associated 'logon' events, just the 'logoff'
events.

File and Print sharing is enabled on this server.

There are several published file shares (all hidden); and there are
individuals who are authorized to use those shares. The security log does
contain 540/538 'pairs' that reflect the credentials of these known users
(user/domain). (These are also 'Logon Type 3') But the number of 538 NT
AUTHORITY/ANONYMOUS LOGON events absolutely dwarfs the number of "known user"
logon/logoff events.

The server itself is not a domain controller. It was until recently a
member of a NT domain, and now is under AD (I don't know how to state that
with any accuracy). 'Known user' logon/logoff events are present for both
the 'older' NT domain, and the newer 'AD' whatever).

I've scoured newsgroups and the MS web site without any luck whatsoever.
Any feedback would be greatly appreciated.

More about : event 538 logon type authority anonymous logon

Anonymous
a b 8 Security
March 12, 2005 12:42:55 AM

Archived from groups: microsoft.public.win2000.security (More info?)

It is common to see those Events on computers using Windows networking and
that have file and print sharing and Client for Microsoft networks enabled.
Those often are null sessions used by the computer browser service. While
null sessions can be used to enumerate users, groups, and shares you can
mitigate the risk by using a firewall to prevent internet access to null
sessions, enforcing strong passwords on your network, and making sure your
share/folder permissions only allow authorized users access.

There are things you can do to reduce there occurrence as ling as the
changes do not interfere with your network access for users. For instance
disabling netbios over tcp/ip, disabling the computer browser service, and
configuring the security option for "additional restrictions for anonymous
access" to be " no access without explicit anonymous permissions". If you
disable netbios over tcp/ip on a computer it will no longer show in or be
able to use My Network Places but access to shares can still be done via
fully qualified domain name or possibly even netbios name as long as dns can
resolve the non FQDN by appending parent suffix to the request. The link
below explains anonymous access more and the security option to restrict it
along with possible consequences of doing such. --- Steve

http://support.microsoft.com/?kbid=246261

"/.dz" </.dz@discussions.microsoft.com> wrote in message
news:480AE832-9FE3-4740-A265-6F6CA5A898FD@microsoft.com...
> The security event log on our W2K, SP4 server has hundreds of the above
> messages in it. There are no associated 'logon' events, just the 'logoff'
> events.
>
> File and Print sharing is enabled on this server.
>
> There are several published file shares (all hidden); and there are
> individuals who are authorized to use those shares. The security log does
> contain 540/538 'pairs' that reflect the credentials of these known users
> (user/domain). (These are also 'Logon Type 3') But the number of 538 NT
> AUTHORITY/ANONYMOUS LOGON events absolutely dwarfs the number of "known
> user"
> logon/logoff events.
>
> The server itself is not a domain controller. It was until recently a
> member of a NT domain, and now is under AD (I don't know how to state that
> with any accuracy). 'Known user' logon/logoff events are present for
> both
> the 'older' NT domain, and the newer 'AD' whatever).
>
> I've scoured newsgroups and the MS web site without any luck whatsoever.
> Any feedback would be greatly appreciated.
>
Anonymous
a b 8 Security
March 16, 2005 4:41:05 PM

Archived from groups: microsoft.public.win2000.security (More info?)

Steve:
First thanks very much for the response. I've noticed that your name is on
a lot of the responses in this forum and I appreciate the help as much as I'm
sure the other people do as well.

So anytime you get tired of this thread, it will probably die -- but I will
continue to ask questions as long as you continue to respond.

In your response, you mentioned 'null sessions'. In other articles I've
read, there is a reference to using the statement [net use \\servername\ipc$
"""" /u:""] to check if null sessions are able to be created. When I
attempted this statement from my workstation, targetting the 'servername'
being discussed in this posting, I received the "Logon failure: unknown user
name or bad password" message at the workstation, and the server logged an
event 529 Logon failure, explicitly indicating my userid, workstation, and
domain. From this info, I'm assuming that the 'null sessions' discussion
does not apply to my situation. Is that a valid conclusion? Also, the
Computer Browser service is disabled (and has been since installation) on the
server. Am I also 'on-track' here in that these two items are directly
related? (That is, 'null sessions' are enabled - i.e., required - for the
Computer Browser service to function)

I want to ask about the other items in your response as well, but to keep
the dialog within reasonable bounds, I'm electing to go through it one item
at a time --- starting (I think) with the most clearcut.

Also in this thread, I need to about the 'Client for Microsoft Networks' .
The server has this protocol enabled. Two further questions: a) This client
is only necessary if the computer (the server in this case) wants to access
other NETBIOS resources on the net; it is not required for other computers on
the net to reach its (the server's) resources. Is this correct? b) the
'Client for Microsoft Networks' is not responsible for the 538 logout events
mentioned in the original post?

Any further dialog is greatly appreciated.
../dz

"Steven L Umbach" wrote:

> It is common to see those Events on computers using Windows networking and
> that have file and print sharing and Client for Microsoft networks enabled.
> Those often are null sessions used by the computer browser service. While
> null sessions can be used to enumerate users, groups, and shares you can
> mitigate the risk by using a firewall to prevent internet access to null
> sessions, enforcing strong passwords on your network, and making sure your
> share/folder permissions only allow authorized users access.
>
> There are things you can do to reduce there occurrence as ling as the
> changes do not interfere with your network access for users. For instance
> disabling netbios over tcp/ip, disabling the computer browser service, and
> configuring the security option for "additional restrictions for anonymous
> access" to be " no access without explicit anonymous permissions". If you
> disable netbios over tcp/ip on a computer it will no longer show in or be
> able to use My Network Places but access to shares can still be done via
> fully qualified domain name or possibly even netbios name as long as dns can
> resolve the non FQDN by appending parent suffix to the request. The link
> below explains anonymous access more and the security option to restrict it
> along with possible consequences of doing such. --- Steve
>
> http://support.microsoft.com/?kbid=246261
>
> "/.dz" </.dz@discussions.microsoft.com> wrote in message
> news:480AE832-9FE3-4740-A265-6F6CA5A898FD@microsoft.com...
> > The security event log on our W2K, SP4 server has hundreds of the above
> > messages in it. There are no associated 'logon' events, just the 'logoff'
> > events.
> >
> > File and Print sharing is enabled on this server.
> >
> > There are several published file shares (all hidden); and there are
> > individuals who are authorized to use those shares. The security log does
> > contain 540/538 'pairs' that reflect the credentials of these known users
> > (user/domain). (These are also 'Logon Type 3') But the number of 538 NT
> > AUTHORITY/ANONYMOUS LOGON events absolutely dwarfs the number of "known
> > user"
> > logon/logoff events.
> >
> > The server itself is not a domain controller. It was until recently a
> > member of a NT domain, and now is under AD (I don't know how to state that
> > with any accuracy). 'Known user' logon/logoff events are present for
> > both
> > the 'older' NT domain, and the newer 'AD' whatever).
> >
> > I've scoured newsgroups and the MS web site without any luck whatsoever.
> > Any feedback would be greatly appreciated.
> >
>
>
>
Related resources
Anonymous
a b 8 Security
March 17, 2005 3:12:14 AM

Archived from groups: microsoft.public.win2000.security (More info?)

I am experiencing something different than you are [ as shown below]. As
long as the security option for additional restrictions for anonymous access
is NOT set to no access without explicit anonymous permissions I am able to
create a null session. When I do have no access without explicit anonymous
permissions enabled I can not create a null session and I simply get a
system error 5 has occurred - access is denied. Even when access was denied
to my null session an Event ID 538 is recorded in the security log of my
server for successful anonymous logoff which indicates that these events may
be recorded even if a null session is denied. You might want to see if you
have any current sessons to your server before you try null session with "
net use " command and delete them if there are any and try again. I doubt
Client for Microsoft Networks enabled on your server is causing the null
sessions to be created to your server. If your server does not need to logon
to a domain or access shares/resources on other computers then you should be
able to diable it with no ill effect. A dedicated web server for instance
would not need to use Client for Microsoft Networks. --- Steve

D:\Documents and Settings\Steve>net use \\192.168.1.105\ipc$ "" /u:""
The command completed successfully.


D:\Documents and Settings\Steve>net use \\192.168.1.105\ipc$ "" /u:""
System error 5 has occurred.

Access is denied.

Event Type: Success Audit
Event Source: Security
Event Category: Logon/Logoff
Event ID: 538
Date: 3/16/2005
Time: 11:56:16 PM
User: NT AUTHORITY\ANONYMOUS LOGON
Computer: SERVER1-2000
Description:
User Logoff:
User Name: ANONYMOUS LOGON
Domain: NT AUTHORITY
Logon ID: (0x0,0x2CFBA3)
Logon Type: 3


"/.dz" <dz@discussions.microsoft.com> wrote in message
news:1D63D35D-431D-4A78-83BD-AE4A2E8EE0D1@microsoft.com...
> Steve:
> First thanks very much for the response. I've noticed that your name is
> on
> a lot of the responses in this forum and I appreciate the help as much as
> I'm
> sure the other people do as well.
>
> So anytime you get tired of this thread, it will probably die -- but I
> will
> continue to ask questions as long as you continue to respond.
>
> In your response, you mentioned 'null sessions'. In other articles I've
> read, there is a reference to using the statement [net use
> \\servername\ipc$
> """" /u:""] to check if null sessions are able to be created. When I
> attempted this statement from my workstation, targetting the 'servername'
> being discussed in this posting, I received the "Logon failure: unknown
> user
> name or bad password" message at the workstation, and the server logged an
> event 529 Logon failure, explicitly indicating my userid, workstation, and
> domain. From this info, I'm assuming that the 'null sessions' discussion
> does not apply to my situation. Is that a valid conclusion? Also, the
> Computer Browser service is disabled (and has been since installation) on
> the
> server. Am I also 'on-track' here in that these two items are directly
> related? (That is, 'null sessions' are enabled - i.e., required - for the
> Computer Browser service to function)
>
> I want to ask about the other items in your response as well, but to keep
> the dialog within reasonable bounds, I'm electing to go through it one
> item
> at a time --- starting (I think) with the most clearcut.
>
> Also in this thread, I need to about the 'Client for Microsoft Networks' .
> The server has this protocol enabled. Two further questions: a) This
> client
> is only necessary if the computer (the server in this case) wants to
> access
> other NETBIOS resources on the net; it is not required for other computers
> on
> the net to reach its (the server's) resources. Is this correct? b) the
> 'Client for Microsoft Networks' is not responsible for the 538 logout
> events
> mentioned in the original post?
>
> Any further dialog is greatly appreciated.
> ./dz
>
> "Steven L Umbach" wrote:
>
>> It is common to see those Events on computers using Windows networking
>> and
>> that have file and print sharing and Client for Microsoft networks
>> enabled.
>> Those often are null sessions used by the computer browser service. While
>> null sessions can be used to enumerate users, groups, and shares you can
>> mitigate the risk by using a firewall to prevent internet access to null
>> sessions, enforcing strong passwords on your network, and making sure
>> your
>> share/folder permissions only allow authorized users access.
>>
>> There are things you can do to reduce there occurrence as ling as the
>> changes do not interfere with your network access for users. For instance
>> disabling netbios over tcp/ip, disabling the computer browser service,
>> and
>> configuring the security option for "additional restrictions for
>> anonymous
>> access" to be " no access without explicit anonymous permissions". If
>> you
>> disable netbios over tcp/ip on a computer it will no longer show in or be
>> able to use My Network Places but access to shares can still be done via
>> fully qualified domain name or possibly even netbios name as long as dns
>> can
>> resolve the non FQDN by appending parent suffix to the request. The link
>> below explains anonymous access more and the security option to restrict
>> it
>> along with possible consequences of doing such. --- Steve
>>
>> http://support.microsoft.com/?kbid=246261
>>
>> "/.dz" </.dz@discussions.microsoft.com> wrote in message
>> news:480AE832-9FE3-4740-A265-6F6CA5A898FD@microsoft.com...
>> > The security event log on our W2K, SP4 server has hundreds of the above
>> > messages in it. There are no associated 'logon' events, just the
>> > 'logoff'
>> > events.
>> >
>> > File and Print sharing is enabled on this server.
>> >
>> > There are several published file shares (all hidden); and there are
>> > individuals who are authorized to use those shares. The security log
>> > does
>> > contain 540/538 'pairs' that reflect the credentials of these known
>> > users
>> > (user/domain). (These are also 'Logon Type 3') But the number of 538
>> > NT
>> > AUTHORITY/ANONYMOUS LOGON events absolutely dwarfs the number of "known
>> > user"
>> > logon/logoff events.
>> >
>> > The server itself is not a domain controller. It was until recently a
>> > member of a NT domain, and now is under AD (I don't know how to state
>> > that
>> > with any accuracy). 'Known user' logon/logoff events are present for
>> > both
>> > the 'older' NT domain, and the newer 'AD' whatever).
>> >
>> > I've scoured newsgroups and the MS web site without any luck
>> > whatsoever.
>> > Any feedback would be greatly appreciated.
>> >
>>
>>
>>
Anonymous
a b 8 Security
March 17, 2005 2:03:05 PM

Archived from groups: microsoft.public.win2000.security (More info?)

Again, thanks. Here's what I know now that I didn't prior to your response --
Your version of the 'null session' command has two less ""s in it. And that
makes it work! So now I can indeed verify that I am able to establish a null
session with my server; and 'yes' it apparently does log a 538 upon session
termination. But allow me a further quesiton: Since I have the 'Computer
Browser' service disabled on the server, why are 'null sessions' still
allowed? I was under the impression that null sessions only existed to
facilitate the 'enumeration' of resouces that the browsing capability
supports; and therefore by disabling the Computer Browser service I would
effectively prevent 'null sessions' from occurring. ??

"Steven L Umbach" wrote:

> I am experiencing something different than you are [ as shown below]. As
> long as the security option for additional restrictions for anonymous access
> is NOT set to no access without explicit anonymous permissions I am able to
> create a null session. When I do have no access without explicit anonymous
> permissions enabled I can not create a null session and I simply get a
> system error 5 has occurred - access is denied. Even when access was denied
> to my null session an Event ID 538 is recorded in the security log of my
> server for successful anonymous logoff which indicates that these events may
> be recorded even if a null session is denied. You might want to see if you
> have any current sessons to your server before you try null session with "
> net use " command and delete them if there are any and try again. I doubt
> Client for Microsoft Networks enabled on your server is causing the null
> sessions to be created to your server. If your server does not need to logon
> to a domain or access shares/resources on other computers then you should be
> able to diable it with no ill effect. A dedicated web server for instance
> would not need to use Client for Microsoft Networks. --- Steve
>
> D:\Documents and Settings\Steve>net use \\192.168.1.105\ipc$ "" /u:""
> The command completed successfully.
>
>
> D:\Documents and Settings\Steve>net use \\192.168.1.105\ipc$ "" /u:""
> System error 5 has occurred.
>
> Access is denied.
>
> Event Type: Success Audit
> Event Source: Security
> Event Category: Logon/Logoff
> Event ID: 538
> Date: 3/16/2005
> Time: 11:56:16 PM
> User: NT AUTHORITY\ANONYMOUS LOGON
> Computer: SERVER1-2000
> Description:
> User Logoff:
> User Name: ANONYMOUS LOGON
> Domain: NT AUTHORITY
> Logon ID: (0x0,0x2CFBA3)
> Logon Type: 3
>
>
> "/.dz" <dz@discussions.microsoft.com> wrote in message
> news:1D63D35D-431D-4A78-83BD-AE4A2E8EE0D1@microsoft.com...
> > Steve:
> > First thanks very much for the response. I've noticed that your name is
> > on
> > a lot of the responses in this forum and I appreciate the help as much as
> > I'm
> > sure the other people do as well.
> >
> > So anytime you get tired of this thread, it will probably die -- but I
> > will
> > continue to ask questions as long as you continue to respond.
> >
> > In your response, you mentioned 'null sessions'. In other articles I've
> > read, there is a reference to using the statement [net use
> > \\servername\ipc$
> > """" /u:""] to check if null sessions are able to be created. When I
> > attempted this statement from my workstation, targetting the 'servername'
> > being discussed in this posting, I received the "Logon failure: unknown
> > user
> > name or bad password" message at the workstation, and the server logged an
> > event 529 Logon failure, explicitly indicating my userid, workstation, and
> > domain. From this info, I'm assuming that the 'null sessions' discussion
> > does not apply to my situation. Is that a valid conclusion? Also, the
> > Computer Browser service is disabled (and has been since installation) on
> > the
> > server. Am I also 'on-track' here in that these two items are directly
> > related? (That is, 'null sessions' are enabled - i.e., required - for the
> > Computer Browser service to function)
> >
> > I want to ask about the other items in your response as well, but to keep
> > the dialog within reasonable bounds, I'm electing to go through it one
> > item
> > at a time --- starting (I think) with the most clearcut.
> >
> > Also in this thread, I need to about the 'Client for Microsoft Networks' .
> > The server has this protocol enabled. Two further questions: a) This
> > client
> > is only necessary if the computer (the server in this case) wants to
> > access
> > other NETBIOS resources on the net; it is not required for other computers
> > on
> > the net to reach its (the server's) resources. Is this correct? b) the
> > 'Client for Microsoft Networks' is not responsible for the 538 logout
> > events
> > mentioned in the original post?
> >
> > Any further dialog is greatly appreciated.
> > ./dz
> >
> > "Steven L Umbach" wrote:
> >
> >> It is common to see those Events on computers using Windows networking
> >> and
> >> that have file and print sharing and Client for Microsoft networks
> >> enabled.
> >> Those often are null sessions used by the computer browser service. While
> >> null sessions can be used to enumerate users, groups, and shares you can
> >> mitigate the risk by using a firewall to prevent internet access to null
> >> sessions, enforcing strong passwords on your network, and making sure
> >> your
> >> share/folder permissions only allow authorized users access.
> >>
> >> There are things you can do to reduce there occurrence as ling as the
> >> changes do not interfere with your network access for users. For instance
> >> disabling netbios over tcp/ip, disabling the computer browser service,
> >> and
> >> configuring the security option for "additional restrictions for
> >> anonymous
> >> access" to be " no access without explicit anonymous permissions". If
> >> you
> >> disable netbios over tcp/ip on a computer it will no longer show in or be
> >> able to use My Network Places but access to shares can still be done via
> >> fully qualified domain name or possibly even netbios name as long as dns
> >> can
> >> resolve the non FQDN by appending parent suffix to the request. The link
> >> below explains anonymous access more and the security option to restrict
> >> it
> >> along with possible consequences of doing such. --- Steve
> >>
> >> http://support.microsoft.com/?kbid=246261
> >>
> >> "/.dz" </.dz@discussions.microsoft.com> wrote in message
> >> news:480AE832-9FE3-4740-A265-6F6CA5A898FD@microsoft.com...
> >> > The security event log on our W2K, SP4 server has hundreds of the above
> >> > messages in it. There are no associated 'logon' events, just the
> >> > 'logoff'
> >> > events.
> >> >
> >> > File and Print sharing is enabled on this server.
> >> >
> >> > There are several published file shares (all hidden); and there are
> >> > individuals who are authorized to use those shares. The security log
> >> > does
> >> > contain 540/538 'pairs' that reflect the credentials of these known
> >> > users
> >> > (user/domain). (These are also 'Logon Type 3') But the number of 538
> >> > NT
> >> > AUTHORITY/ANONYMOUS LOGON events absolutely dwarfs the number of "known
> >> > user"
> >> > logon/logoff events.
> >> >
> >> > The server itself is not a domain controller. It was until recently a
> >> > member of a NT domain, and now is under AD (I don't know how to state
> >> > that
> >> > with any accuracy). 'Known user' logon/logoff events are present for
> >> > both
> >> > the 'older' NT domain, and the newer 'AD' whatever).
> >> >
> >> > I've scoured newsgroups and the MS web site without any luck
> >> > whatsoever.
> >> > Any feedback would be greatly appreciated.
> >> >
> >>
> >>
> >>
>
>
>
Anonymous
a b 8 Security
March 18, 2005 1:00:34 AM

Archived from groups: microsoft.public.win2000.security (More info?)

The browser service is just one and the most common use of null sessions.
However disabling the browser service simply prevents the computer from
becoming a master browser or backup browser. If you can change the security
option for additional restrictions for anonymous access to be no access
without explicit anonymous permissions you will prevent null connections
though apparently you may still see anonymous logon events in the security
log as I experienced. The KB article below explains more on how to do this
but be sure to read the consequences first. --- Steve

http://support.microsoft.com/?kbid=246261

The following tasks are restricted when the RestrictAnonymous registry value
is set to 2 on a Windows 2000-based domain controller: . Down-level member
workstations or servers are not able to set up a netlogon secure channel.
. Down-level domain controllers in trusting domains are not be able to
set up a netlogon secure channel.
. Microsoft Windows NT users are not able to change their passwords
after they expire. Also, Macintosh users are not able to change their
passwords at all.
. The Browser service is not able to retrieve domain lists or server
lists from backup browsers, master browsers or domain master browsers that
are running on computers with the RestrictAnonymous registry value set to 2.
Because of this, any program that relies on the Browser service does not
function properly


"/.dz" <dz@discussions.microsoft.com> wrote in message
news:6D02852B-4580-422D-A4F1-81D7CC52C8FA@microsoft.com...
> Again, thanks. Here's what I know now that I didn't prior to your
> response --
> Your version of the 'null session' command has two less ""s in it. And
> that
> makes it work! So now I can indeed verify that I am able to establish a
> null
> session with my server; and 'yes' it apparently does log a 538 upon
> session
> termination. But allow me a further quesiton: Since I have the 'Computer
> Browser' service disabled on the server, why are 'null sessions' still
> allowed? I was under the impression that null sessions only existed to
> facilitate the 'enumeration' of resouces that the browsing capability
> supports; and therefore by disabling the Computer Browser service I would
> effectively prevent 'null sessions' from occurring. ??
>
> "Steven L Umbach" wrote:
>
>> I am experiencing something different than you are [ as shown below]. As
>> long as the security option for additional restrictions for anonymous
>> access
>> is NOT set to no access without explicit anonymous permissions I am able
>> to
>> create a null session. When I do have no access without explicit
>> anonymous
>> permissions enabled I can not create a null session and I simply get a
>> system error 5 has occurred - access is denied. Even when access was
>> denied
>> to my null session an Event ID 538 is recorded in the security log of my
>> server for successful anonymous logoff which indicates that these events
>> may
>> be recorded even if a null session is denied. You might want to see if
>> you
>> have any current sessons to your server before you try null session with
>> "
>> net use " command and delete them if there are any and try again. I doubt
>> Client for Microsoft Networks enabled on your server is causing the null
>> sessions to be created to your server. If your server does not need to
>> logon
>> to a domain or access shares/resources on other computers then you should
>> be
>> able to diable it with no ill effect. A dedicated web server for instance
>> would not need to use Client for Microsoft Networks. --- Steve
>>
>> D:\Documents and Settings\Steve>net use \\192.168.1.105\ipc$ "" /u:""
>> The command completed successfully.
>>
>>
>> D:\Documents and Settings\Steve>net use \\192.168.1.105\ipc$ "" /u:""
>> System error 5 has occurred.
>>
>> Access is denied.
>>
>> Event Type: Success Audit
>> Event Source: Security
>> Event Category: Logon/Logoff
>> Event ID: 538
>> Date: 3/16/2005
>> Time: 11:56:16 PM
>> User: NT AUTHORITY\ANONYMOUS LOGON
>> Computer: SERVER1-2000
>> Description:
>> User Logoff:
>> User Name: ANONYMOUS LOGON
>> Domain: NT AUTHORITY
>> Logon ID: (0x0,0x2CFBA3)
>> Logon Type: 3
>>
>>
>> "/.dz" <dz@discussions.microsoft.com> wrote in message
>> news:1D63D35D-431D-4A78-83BD-AE4A2E8EE0D1@microsoft.com...
>> > Steve:
>> > First thanks very much for the response. I've noticed that your name
>> > is
>> > on
>> > a lot of the responses in this forum and I appreciate the help as much
>> > as
>> > I'm
>> > sure the other people do as well.
>> >
>> > So anytime you get tired of this thread, it will probably die -- but I
>> > will
>> > continue to ask questions as long as you continue to respond.
>> >
>> > In your response, you mentioned 'null sessions'. In other articles
>> > I've
>> > read, there is a reference to using the statement [net use
>> > \\servername\ipc$
>> > """" /u:""] to check if null sessions are able to be created. When I
>> > attempted this statement from my workstation, targetting the
>> > 'servername'
>> > being discussed in this posting, I received the "Logon failure: unknown
>> > user
>> > name or bad password" message at the workstation, and the server logged
>> > an
>> > event 529 Logon failure, explicitly indicating my userid, workstation,
>> > and
>> > domain. From this info, I'm assuming that the 'null sessions'
>> > discussion
>> > does not apply to my situation. Is that a valid conclusion? Also, the
>> > Computer Browser service is disabled (and has been since installation)
>> > on
>> > the
>> > server. Am I also 'on-track' here in that these two items are directly
>> > related? (That is, 'null sessions' are enabled - i.e., required - for
>> > the
>> > Computer Browser service to function)
>> >
>> > I want to ask about the other items in your response as well, but to
>> > keep
>> > the dialog within reasonable bounds, I'm electing to go through it one
>> > item
>> > at a time --- starting (I think) with the most clearcut.
>> >
>> > Also in this thread, I need to about the 'Client for Microsoft
>> > Networks' .
>> > The server has this protocol enabled. Two further questions: a) This
>> > client
>> > is only necessary if the computer (the server in this case) wants to
>> > access
>> > other NETBIOS resources on the net; it is not required for other
>> > computers
>> > on
>> > the net to reach its (the server's) resources. Is this correct? b)
>> > the
>> > 'Client for Microsoft Networks' is not responsible for the 538 logout
>> > events
>> > mentioned in the original post?
>> >
>> > Any further dialog is greatly appreciated.
>> > ./dz
>> >
>> > "Steven L Umbach" wrote:
>> >
>> >> It is common to see those Events on computers using Windows networking
>> >> and
>> >> that have file and print sharing and Client for Microsoft networks
>> >> enabled.
>> >> Those often are null sessions used by the computer browser service.
>> >> While
>> >> null sessions can be used to enumerate users, groups, and shares you
>> >> can
>> >> mitigate the risk by using a firewall to prevent internet access to
>> >> null
>> >> sessions, enforcing strong passwords on your network, and making sure
>> >> your
>> >> share/folder permissions only allow authorized users access.
>> >>
>> >> There are things you can do to reduce there occurrence as ling as the
>> >> changes do not interfere with your network access for users. For
>> >> instance
>> >> disabling netbios over tcp/ip, disabling the computer browser service,
>> >> and
>> >> configuring the security option for "additional restrictions for
>> >> anonymous
>> >> access" to be " no access without explicit anonymous permissions". If
>> >> you
>> >> disable netbios over tcp/ip on a computer it will no longer show in or
>> >> be
>> >> able to use My Network Places but access to shares can still be done
>> >> via
>> >> fully qualified domain name or possibly even netbios name as long as
>> >> dns
>> >> can
>> >> resolve the non FQDN by appending parent suffix to the request. The
>> >> link
>> >> below explains anonymous access more and the security option to
>> >> restrict
>> >> it
>> >> along with possible consequences of doing such. --- Steve
>> >>
>> >> http://support.microsoft.com/?kbid=246261
>> >>
>> >> "/.dz" </.dz@discussions.microsoft.com> wrote in message
>> >> news:480AE832-9FE3-4740-A265-6F6CA5A898FD@microsoft.com...
>> >> > The security event log on our W2K, SP4 server has hundreds of the
>> >> > above
>> >> > messages in it. There are no associated 'logon' events, just the
>> >> > 'logoff'
>> >> > events.
>> >> >
>> >> > File and Print sharing is enabled on this server.
>> >> >
>> >> > There are several published file shares (all hidden); and there are
>> >> > individuals who are authorized to use those shares. The security
>> >> > log
>> >> > does
>> >> > contain 540/538 'pairs' that reflect the credentials of these known
>> >> > users
>> >> > (user/domain). (These are also 'Logon Type 3') But the number of
>> >> > 538
>> >> > NT
>> >> > AUTHORITY/ANONYMOUS LOGON events absolutely dwarfs the number of
>> >> > "known
>> >> > user"
>> >> > logon/logoff events.
>> >> >
>> >> > The server itself is not a domain controller. It was until recently
>> >> > a
>> >> > member of a NT domain, and now is under AD (I don't know how to
>> >> > state
>> >> > that
>> >> > with any accuracy). 'Known user' logon/logoff events are present
>> >> > for
>> >> > both
>> >> > the 'older' NT domain, and the newer 'AD' whatever).
>> >> >
>> >> > I've scoured newsgroups and the MS web site without any luck
>> >> > whatsoever.
>> >> > Any feedback would be greatly appreciated.
>> >> >
>> >>
>> >>
>> >>
>>
>>
>>
Anonymous
a b 8 Security
March 18, 2005 2:17:05 PM

Archived from groups: microsoft.public.win2000.security (More info?)

Steve:
As before, thank you for the explanation of the relationship between the
'null sessions' and the Computer Browser service -- one less source of
ambiguity for me to deal with. Unfortunately, for reasons related to 'job
security', I am not able to investigate the 'restrict anonymous access'
option at this time. However, if at some point in the near future I am able
to, I will add my experience to this dialog.

That having been said, and if you are still willing, I'd like to return to
the original response you provided and ask in detail about one of the other
points -- disabling NETBIOS over tcp/ip. I'm fairly certain that I
understand the premise of 'name resolution' and you've indicated that as long
as the file-share users reference the share with either a FQDN (or
equivalently, the workstation TCP/IP Advanced Properties DNS settings has an
appropriate suffix in the list that results in a FQDN), name resolution
should proceed OK. Question: Does this imply that NETBIOS - from the
standpoint of file sharing - is only needed for name resolution? There's no
other aspect to file sharing that is dependent upon NETBIOS?
../dz

"Steven L Umbach" wrote:

> The browser service is just one and the most common use of null sessions.
> However disabling the browser service simply prevents the computer from
> becoming a master browser or backup browser. If you can change the security
> option for additional restrictions for anonymous access to be no access
> without explicit anonymous permissions you will prevent null connections
> though apparently you may still see anonymous logon events in the security
> log as I experienced. The KB article below explains more on how to do this
> but be sure to read the consequences first. --- Steve
>
> http://support.microsoft.com/?kbid=246261
>
> The following tasks are restricted when the RestrictAnonymous registry value
> is set to 2 on a Windows 2000-based domain controller: . Down-level member
> workstations or servers are not able to set up a netlogon secure channel.
> . Down-level domain controllers in trusting domains are not be able to
> set up a netlogon secure channel.
> . Microsoft Windows NT users are not able to change their passwords
> after they expire. Also, Macintosh users are not able to change their
> passwords at all.
> . The Browser service is not able to retrieve domain lists or server
> lists from backup browsers, master browsers or domain master browsers that
> are running on computers with the RestrictAnonymous registry value set to 2.
> Because of this, any program that relies on the Browser service does not
> function properly
>
>
> "/.dz" <dz@discussions.microsoft.com> wrote in message
> news:6D02852B-4580-422D-A4F1-81D7CC52C8FA@microsoft.com...
> > Again, thanks. Here's what I know now that I didn't prior to your
> > response --
> > Your version of the 'null session' command has two less ""s in it. And
> > that
> > makes it work! So now I can indeed verify that I am able to establish a
> > null
> > session with my server; and 'yes' it apparently does log a 538 upon
> > session
> > termination. But allow me a further quesiton: Since I have the 'Computer
> > Browser' service disabled on the server, why are 'null sessions' still
> > allowed? I was under the impression that null sessions only existed to
> > facilitate the 'enumeration' of resouces that the browsing capability
> > supports; and therefore by disabling the Computer Browser service I would
> > effectively prevent 'null sessions' from occurring. ??
> >
> > "Steven L Umbach" wrote:
> >
> >> I am experiencing something different than you are [ as shown below]. As
> >> long as the security option for additional restrictions for anonymous
> >> access
> >> is NOT set to no access without explicit anonymous permissions I am able
> >> to
> >> create a null session. When I do have no access without explicit
> >> anonymous
> >> permissions enabled I can not create a null session and I simply get a
> >> system error 5 has occurred - access is denied. Even when access was
> >> denied
> >> to my null session an Event ID 538 is recorded in the security log of my
> >> server for successful anonymous logoff which indicates that these events
> >> may
> >> be recorded even if a null session is denied. You might want to see if
> >> you
> >> have any current sessons to your server before you try null session with
> >> "
> >> net use " command and delete them if there are any and try again. I doubt
> >> Client for Microsoft Networks enabled on your server is causing the null
> >> sessions to be created to your server. If your server does not need to
> >> logon
> >> to a domain or access shares/resources on other computers then you should
> >> be
> >> able to diable it with no ill effect. A dedicated web server for instance
> >> would not need to use Client for Microsoft Networks. --- Steve
> >>
> >> D:\Documents and Settings\Steve>net use \\192.168.1.105\ipc$ "" /u:""
> >> The command completed successfully.
> >>
> >>
> >> D:\Documents and Settings\Steve>net use \\192.168.1.105\ipc$ "" /u:""
> >> System error 5 has occurred.
> >>
> >> Access is denied.
> >>
> >> Event Type: Success Audit
> >> Event Source: Security
> >> Event Category: Logon/Logoff
> >> Event ID: 538
> >> Date: 3/16/2005
> >> Time: 11:56:16 PM
> >> User: NT AUTHORITY\ANONYMOUS LOGON
> >> Computer: SERVER1-2000
> >> Description:
> >> User Logoff:
> >> User Name: ANONYMOUS LOGON
> >> Domain: NT AUTHORITY
> >> Logon ID: (0x0,0x2CFBA3)
> >> Logon Type: 3
> >>
> >>
> >> "/.dz" <dz@discussions.microsoft.com> wrote in message
> >> news:1D63D35D-431D-4A78-83BD-AE4A2E8EE0D1@microsoft.com...
> >> > Steve:
> >> > First thanks very much for the response. I've noticed that your name
> >> > is
> >> > on
> >> > a lot of the responses in this forum and I appreciate the help as much
> >> > as
> >> > I'm
> >> > sure the other people do as well.
> >> >
> >> > So anytime you get tired of this thread, it will probably die -- but I
> >> > will
> >> > continue to ask questions as long as you continue to respond.
> >> >
> >> > In your response, you mentioned 'null sessions'. In other articles
> >> > I've
> >> > read, there is a reference to using the statement [net use
> >> > \\servername\ipc$
> >> > """" /u:""] to check if null sessions are able to be created. When I
> >> > attempted this statement from my workstation, targetting the
> >> > 'servername'
> >> > being discussed in this posting, I received the "Logon failure: unknown
> >> > user
> >> > name or bad password" message at the workstation, and the server logged
> >> > an
> >> > event 529 Logon failure, explicitly indicating my userid, workstation,
> >> > and
> >> > domain. From this info, I'm assuming that the 'null sessions'
> >> > discussion
> >> > does not apply to my situation. Is that a valid conclusion? Also, the
> >> > Computer Browser service is disabled (and has been since installation)
> >> > on
> >> > the
> >> > server. Am I also 'on-track' here in that these two items are directly
> >> > related? (That is, 'null sessions' are enabled - i.e., required - for
> >> > the
> >> > Computer Browser service to function)
> >> >
> >> > I want to ask about the other items in your response as well, but to
> >> > keep
> >> > the dialog within reasonable bounds, I'm electing to go through it one
> >> > item
> >> > at a time --- starting (I think) with the most clearcut.
> >> >
> >> > Also in this thread, I need to about the 'Client for Microsoft
> >> > Networks' .
> >> > The server has this protocol enabled. Two further questions: a) This
> >> > client
> >> > is only necessary if the computer (the server in this case) wants to
> >> > access
> >> > other NETBIOS resources on the net; it is not required for other
> >> > computers
> >> > on
> >> > the net to reach its (the server's) resources. Is this correct? b)
> >> > the
> >> > 'Client for Microsoft Networks' is not responsible for the 538 logout
> >> > events
> >> > mentioned in the original post?
> >> >
> >> > Any further dialog is greatly appreciated.
> >> > ./dz
> >> >
> >> > "Steven L Umbach" wrote:
> >> >
> >> >> It is common to see those Events on computers using Windows networking
> >> >> and
> >> >> that have file and print sharing and Client for Microsoft networks
> >> >> enabled.
> >> >> Those often are null sessions used by the computer browser service.
> >> >> While
> >> >> null sessions can be used to enumerate users, groups, and shares you
> >> >> can
> >> >> mitigate the risk by using a firewall to prevent internet access to
> >> >> null
> >> >> sessions, enforcing strong passwords on your network, and making sure
> >> >> your
> >> >> share/folder permissions only allow authorized users access.
> >> >>
> >> >> There are things you can do to reduce there occurrence as ling as the
> >> >> changes do not interfere with your network access for users. For
> >> >> instance
> >> >> disabling netbios over tcp/ip, disabling the computer browser service,
> >> >> and
> >> >> configuring the security option for "additional restrictions for
> >> >> anonymous
> >> >> access" to be " no access without explicit anonymous permissions". If
> >> >> you
> >> >> disable netbios over tcp/ip on a computer it will no longer show in or
> >> >> be
> >> >> able to use My Network Places but access to shares can still be done
> >> >> via
> >> >> fully qualified domain name or possibly even netbios name as long as
> >> >> dns
> >> >> can
> >> >> resolve the non FQDN by appending parent suffix to the request. The
> >> >> link
> >> >> below explains anonymous access more and the security option to
> >> >> restrict
> >> >> it
> >> >> along with possible consequences of doing such. --- Steve
> >> >>
> >> >> http://support.microsoft.com/?kbid=246261
> >> >>
> >> >> "/.dz" </.dz@discussions.microsoft.com> wrote in message
> >> >> news:480AE832-9FE3-4740-A265-6F6CA5A898FD@microsoft.com...
> >> >> > The security event log on our W2K, SP4 server has hundreds of the
> >> >> > above
> >> >> > messages in it. There are no associated 'logon' events, just the
> >> >> > 'logoff'
> >> >> > events.
> >> >> >
> >> >> > File and Print sharing is enabled on this server.
> >> >> >
> >> >> > There are several published file shares (all hidden); and there are
> >> >> > individuals who are authorized to use those shares. The security
> >> >> > log
> >> >> > does
> >> >> > contain 540/538 'pairs' that reflect the credentials of these known
> >> >> > users
> >> >> > (user/domain). (These are also 'Logon Type 3') But the number of
> >> >> > 538
> >> >> > NT
> >> >> > AUTHORITY/ANONYMOUS LOGON events absolutely dwarfs the number of
> >> >> > "known
> >> >> > user"
> >> >> > logon/logoff events.
> >> >> >
> >> >> > The server itself is not a domain controller. It was until recently
> >> >> > a
> >> >> > member of a NT domain, and now is under AD (I don't know how to
> >> >> > state
> >> >> > that
> >> >> > with any accuracy). 'Known user' logon/logoff events are present
> >> >> > for
> >> >> > both
> >> >> > the 'older' NT domain, and the newer 'AD' whatever).
> >> >> >
> >> >> > I've scoured newsgroups and the MS web site without any luck
> >> >> > whatsoever.
> >> >> > Any feedback would be greatly appreciated.
> >> >> >
> >> >>
> >> >>
> >> >>
> >>
> >>
> >>
>
>
>
Anonymous
a b 8 Security
March 19, 2005 12:23:38 AM

Archived from groups: microsoft.public.win2000.security (More info?)

First off disabling netbios over tcp/ip will not stop null sessions but it
may reduce them. Netbios over tcp/ip is legacy [W98/NT4.0, etc] file and
print sharing that uses ports 137UDP/138UDP/139TCP for netbios naming,
transport, and session services. It will use broadcasts only, if a wins
server is not available. NBT [net bios over tcp/ip] uses port 137 UDP for
naming for client to contact wins server, 138 UDP for browse list
maintenance, and 139 TCP for actual file sharing. Legacy clients can only
use NBT and if disabled will not be able to do any name resolution,
browsing, or file sharing.

Windows 2000/XP/2003 can use either NBT or CIFS [port 445TCP] and also DNS
for name resolution of course. If NBT is disabled then Windows 2000/XP/2003
will use DNS and port 445TCP for file and print sharing. A Windows 2000/XP
Pro/2003 domain computer will always use dns name resolution first for any
name resolution request. It will append parent domain suffix [or whatever
you configure] to a non FQDN request. Windows 2000/XP/2003 in a workgroup
however will use NBT first for name resolution for a non FQDN if it is
enabled.

Care should be taken before disabling NBT to make sure no computers or
applications need to use it to refer to computers by name. If it is disabled
then for 2000/XP/2003 you can still use names to refer to file shares. DNS
FQDN will work and "flat" computer names may work if your dns can resolve
the names by appending suffixes for domain computers. For non domain
computers you are best using only FQDN when referring to computer names if
NBT is disabled. While NBT is legacy technology it still is widely used in
most of today's networks and still is required in some cases such as for
certain configurations with Exchange and clusters I believe. --- Steve


"/.dz" <dz@discussions.microsoft.com> wrote in message
news:1AC558F8-332E-4CEB-BEC5-2564EB1FFB00@microsoft.com...
> Steve:
> As before, thank you for the explanation of the relationship between the
> 'null sessions' and the Computer Browser service -- one less source of
> ambiguity for me to deal with. Unfortunately, for reasons related to 'job
> security', I am not able to investigate the 'restrict anonymous access'
> option at this time. However, if at some point in the near future I am
> able
> to, I will add my experience to this dialog.
>
> That having been said, and if you are still willing, I'd like to return to
> the original response you provided and ask in detail about one of the
> other
> points -- disabling NETBIOS over tcp/ip. I'm fairly certain that I
> understand the premise of 'name resolution' and you've indicated that as
> long
> as the file-share users reference the share with either a FQDN (or
> equivalently, the workstation TCP/IP Advanced Properties DNS settings has
> an
> appropriate suffix in the list that results in a FQDN), name resolution
> should proceed OK. Question: Does this imply that NETBIOS - from the
> standpoint of file sharing - is only needed for name resolution? There's
> no
> other aspect to file sharing that is dependent upon NETBIOS?
> ./dz
>
> "Steven L Umbach" wrote:
>
>> The browser service is just one and the most common use of null sessions.
>> However disabling the browser service simply prevents the computer from
>> becoming a master browser or backup browser. If you can change the
>> security
>> option for additional restrictions for anonymous access to be no access
>> without explicit anonymous permissions you will prevent null connections
>> though apparently you may still see anonymous logon events in the
>> security
>> log as I experienced. The KB article below explains more on how to do
>> this
>> but be sure to read the consequences first. --- Steve
>>
>> http://support.microsoft.com/?kbid=246261
>>
>> The following tasks are restricted when the RestrictAnonymous registry
>> value
>> is set to 2 on a Windows 2000-based domain controller: . Down-level
>> member
>> workstations or servers are not able to set up a netlogon secure channel.
>> . Down-level domain controllers in trusting domains are not be able
>> to
>> set up a netlogon secure channel.
>> . Microsoft Windows NT users are not able to change their passwords
>> after they expire. Also, Macintosh users are not able to change their
>> passwords at all.
>> . The Browser service is not able to retrieve domain lists or
>> server
>> lists from backup browsers, master browsers or domain master browsers
>> that
>> are running on computers with the RestrictAnonymous registry value set to
>> 2.
>> Because of this, any program that relies on the Browser service does not
>> function properly
>>
>>
>> "/.dz" <dz@discussions.microsoft.com> wrote in message
>> news:6D02852B-4580-422D-A4F1-81D7CC52C8FA@microsoft.com...
>> > Again, thanks. Here's what I know now that I didn't prior to your
>> > response --
>> > Your version of the 'null session' command has two less ""s in it. And
>> > that
>> > makes it work! So now I can indeed verify that I am able to establish
>> > a
>> > null
>> > session with my server; and 'yes' it apparently does log a 538 upon
>> > session
>> > termination. But allow me a further quesiton: Since I have the
>> > 'Computer
>> > Browser' service disabled on the server, why are 'null sessions' still
>> > allowed? I was under the impression that null sessions only existed to
>> > facilitate the 'enumeration' of resouces that the browsing capability
>> > supports; and therefore by disabling the Computer Browser service I
>> > would
>> > effectively prevent 'null sessions' from occurring. ??
>> >
>> > "Steven L Umbach" wrote:
>> >
>> >> I am experiencing something different than you are [ as shown below].
>> >> As
>> >> long as the security option for additional restrictions for anonymous
>> >> access
>> >> is NOT set to no access without explicit anonymous permissions I am
>> >> able
>> >> to
>> >> create a null session. When I do have no access without explicit
>> >> anonymous
>> >> permissions enabled I can not create a null session and I simply get a
>> >> system error 5 has occurred - access is denied. Even when access was
>> >> denied
>> >> to my null session an Event ID 538 is recorded in the security log of
>> >> my
>> >> server for successful anonymous logoff which indicates that these
>> >> events
>> >> may
>> >> be recorded even if a null session is denied. You might want to see if
>> >> you
>> >> have any current sessons to your server before you try null session
>> >> with
>> >> "
>> >> net use " command and delete them if there are any and try again. I
>> >> doubt
>> >> Client for Microsoft Networks enabled on your server is causing the
>> >> null
>> >> sessions to be created to your server. If your server does not need to
>> >> logon
>> >> to a domain or access shares/resources on other computers then you
>> >> should
>> >> be
>> >> able to diable it with no ill effect. A dedicated web server for
>> >> instance
>> >> would not need to use Client for Microsoft Networks. --- Steve
>> >>
>> >> D:\Documents and Settings\Steve>net use \\192.168.1.105\ipc$ "" /u:""
>> >> The command completed successfully.
>> >>
>> >>
>> >> D:\Documents and Settings\Steve>net use \\192.168.1.105\ipc$ "" /u:""
>> >> System error 5 has occurred.
>> >>
>> >> Access is denied.
>> >>
>> >> Event Type: Success Audit
>> >> Event Source: Security
>> >> Event Category: Logon/Logoff
>> >> Event ID: 538
>> >> Date: 3/16/2005
>> >> Time: 11:56:16 PM
>> >> User: NT AUTHORITY\ANONYMOUS LOGON
>> >> Computer: SERVER1-2000
>> >> Description:
>> >> User Logoff:
>> >> User Name: ANONYMOUS LOGON
>> >> Domain: NT AUTHORITY
>> >> Logon ID: (0x0,0x2CFBA3)
>> >> Logon Type: 3
>> >>
>> >>
>> >> "/.dz" <dz@discussions.microsoft.com> wrote in message
>> >> news:1D63D35D-431D-4A78-83BD-AE4A2E8EE0D1@microsoft.com...
>> >> > Steve:
>> >> > First thanks very much for the response. I've noticed that your
>> >> > name
>> >> > is
>> >> > on
>> >> > a lot of the responses in this forum and I appreciate the help as
>> >> > much
>> >> > as
>> >> > I'm
>> >> > sure the other people do as well.
>> >> >
>> >> > So anytime you get tired of this thread, it will probably die -- but
>> >> > I
>> >> > will
>> >> > continue to ask questions as long as you continue to respond.
>> >> >
>> >> > In your response, you mentioned 'null sessions'. In other articles
>> >> > I've
>> >> > read, there is a reference to using the statement [net use
>> >> > \\servername\ipc$
>> >> > """" /u:""] to check if null sessions are able to be created. When
>> >> > I
>> >> > attempted this statement from my workstation, targetting the
>> >> > 'servername'
>> >> > being discussed in this posting, I received the "Logon failure:
>> >> > unknown
>> >> > user
>> >> > name or bad password" message at the workstation, and the server
>> >> > logged
>> >> > an
>> >> > event 529 Logon failure, explicitly indicating my userid,
>> >> > workstation,
>> >> > and
>> >> > domain. From this info, I'm assuming that the 'null sessions'
>> >> > discussion
>> >> > does not apply to my situation. Is that a valid conclusion? Also,
>> >> > the
>> >> > Computer Browser service is disabled (and has been since
>> >> > installation)
>> >> > on
>> >> > the
>> >> > server. Am I also 'on-track' here in that these two items are
>> >> > directly
>> >> > related? (That is, 'null sessions' are enabled - i.e., required -
>> >> > for
>> >> > the
>> >> > Computer Browser service to function)
>> >> >
>> >> > I want to ask about the other items in your response as well, but to
>> >> > keep
>> >> > the dialog within reasonable bounds, I'm electing to go through it
>> >> > one
>> >> > item
>> >> > at a time --- starting (I think) with the most clearcut.
>> >> >
>> >> > Also in this thread, I need to about the 'Client for Microsoft
>> >> > Networks' .
>> >> > The server has this protocol enabled. Two further questions: a)
>> >> > This
>> >> > client
>> >> > is only necessary if the computer (the server in this case) wants to
>> >> > access
>> >> > other NETBIOS resources on the net; it is not required for other
>> >> > computers
>> >> > on
>> >> > the net to reach its (the server's) resources. Is this correct? b)
>> >> > the
>> >> > 'Client for Microsoft Networks' is not responsible for the 538
>> >> > logout
>> >> > events
>> >> > mentioned in the original post?
>> >> >
>> >> > Any further dialog is greatly appreciated.
>> >> > ./dz
>> >> >
>> >> > "Steven L Umbach" wrote:
>> >> >
>> >> >> It is common to see those Events on computers using Windows
>> >> >> networking
>> >> >> and
>> >> >> that have file and print sharing and Client for Microsoft networks
>> >> >> enabled.
>> >> >> Those often are null sessions used by the computer browser service.
>> >> >> While
>> >> >> null sessions can be used to enumerate users, groups, and shares
>> >> >> you
>> >> >> can
>> >> >> mitigate the risk by using a firewall to prevent internet access to
>> >> >> null
>> >> >> sessions, enforcing strong passwords on your network, and making
>> >> >> sure
>> >> >> your
>> >> >> share/folder permissions only allow authorized users access.
>> >> >>
>> >> >> There are things you can do to reduce there occurrence as ling as
>> >> >> the
>> >> >> changes do not interfere with your network access for users. For
>> >> >> instance
>> >> >> disabling netbios over tcp/ip, disabling the computer browser
>> >> >> service,
>> >> >> and
>> >> >> configuring the security option for "additional restrictions for
>> >> >> anonymous
>> >> >> access" to be " no access without explicit anonymous permissions".
>> >> >> If
>> >> >> you
>> >> >> disable netbios over tcp/ip on a computer it will no longer show in
>> >> >> or
>> >> >> be
>> >> >> able to use My Network Places but access to shares can still be
>> >> >> done
>> >> >> via
>> >> >> fully qualified domain name or possibly even netbios name as long
>> >> >> as
>> >> >> dns
>> >> >> can
>> >> >> resolve the non FQDN by appending parent suffix to the request. The
>> >> >> link
>> >> >> below explains anonymous access more and the security option to
>> >> >> restrict
>> >> >> it
>> >> >> along with possible consequences of doing such. --- Steve
>> >> >>
>> >> >> http://support.microsoft.com/?kbid=246261
>> >> >>
>> >> >> "/.dz" </.dz@discussions.microsoft.com> wrote in message
>> >> >> news:480AE832-9FE3-4740-A265-6F6CA5A898FD@microsoft.com...
>> >> >> > The security event log on our W2K, SP4 server has hundreds of the
>> >> >> > above
>> >> >> > messages in it. There are no associated 'logon' events, just the
>> >> >> > 'logoff'
>> >> >> > events.
>> >> >> >
>> >> >> > File and Print sharing is enabled on this server.
>> >> >> >
>> >> >> > There are several published file shares (all hidden); and there
>> >> >> > are
>> >> >> > individuals who are authorized to use those shares. The security
>> >> >> > log
>> >> >> > does
>> >> >> > contain 540/538 'pairs' that reflect the credentials of these
>> >> >> > known
>> >> >> > users
>> >> >> > (user/domain). (These are also 'Logon Type 3') But the number of
>> >> >> > 538
>> >> >> > NT
>> >> >> > AUTHORITY/ANONYMOUS LOGON events absolutely dwarfs the number of
>> >> >> > "known
>> >> >> > user"
>> >> >> > logon/logoff events.
>> >> >> >
>> >> >> > The server itself is not a domain controller. It was until
>> >> >> > recently
>> >> >> > a
>> >> >> > member of a NT domain, and now is under AD (I don't know how to
>> >> >> > state
>> >> >> > that
>> >> >> > with any accuracy). 'Known user' logon/logoff events are
>> >> >> > present
>> >> >> > for
>> >> >> > both
>> >> >> > the 'older' NT domain, and the newer 'AD' whatever).
>> >> >> >
>> >> >> > I've scoured newsgroups and the MS web site without any luck
>> >> >> > whatsoever.
>> >> >> > Any feedback would be greatly appreciated.
>> >> >> >
>> >> >>
>> >> >>
>> >> >>
>> >>
>> >>
>> >>
>>
>>
>>
Anonymous
a b 8 Security
March 22, 2005 3:01:04 PM

Archived from groups: microsoft.public.win2000.security (More info?)

Steve:
I did not lose interest -- but I did have other things to attend to. This
particular thread has become almost a hobby with me -- so you are forewarned;
I will probably keep going until you tire of my questions; and of course, I
appreciate all the information you've already provided regardless of whether
you continue or not.

But if you elected to continue ...

When I read the last response, this is what I 'hear', right or wrong. UDP
137 is used by the client to contact a WINS server for name resolution. UDP
138 I don't understand, unless it's a port simply to listen for responses to
requests issued via UDP 137 and/or broadcasts. TCP 139 I think I understand
-- using NETSTAT I can 'see' a couple of workstations have ESTABLISHED
connections to TCP 139 on my server and recognize the 'foreign' IP address as
valid users of the system.

[By the way, if you happen to know of a relatively concise article that
describes the NetBIOS protocol, perhaps replete with dialog examples, I'd be
interested ....]

../dz


"Steven L Umbach" wrote:

> First off disabling netbios over tcp/ip will not stop null sessions but it
> may reduce them. Netbios over tcp/ip is legacy [W98/NT4.0, etc] file and
> print sharing that uses ports 137UDP/138UDP/139TCP for netbios naming,
> transport, and session services. It will use broadcasts only, if a wins
> server is not available. NBT [net bios over tcp/ip] uses port 137 UDP for
> naming for client to contact wins server, 138 UDP for browse list
> maintenance, and 139 TCP for actual file sharing. Legacy clients can only
> use NBT and if disabled will not be able to do any name resolution,
> browsing, or file sharing.
>
> Windows 2000/XP/2003 can use either NBT or CIFS [port 445TCP] and also DNS
> for name resolution of course. If NBT is disabled then Windows 2000/XP/2003
> will use DNS and port 445TCP for file and print sharing. A Windows 2000/XP
> Pro/2003 domain computer will always use dns name resolution first for any
> name resolution request. It will append parent domain suffix [or whatever
> you configure] to a non FQDN request. Windows 2000/XP/2003 in a workgroup
> however will use NBT first for name resolution for a non FQDN if it is
> enabled.
>
> Care should be taken before disabling NBT to make sure no computers or
> applications need to use it to refer to computers by name. If it is disabled
> then for 2000/XP/2003 you can still use names to refer to file shares. DNS
> FQDN will work and "flat" computer names may work if your dns can resolve
> the names by appending suffixes for domain computers. For non domain
> computers you are best using only FQDN when referring to computer names if
> NBT is disabled. While NBT is legacy technology it still is widely used in
> most of today's networks and still is required in some cases such as for
> certain configurations with Exchange and clusters I believe. --- Steve
>
>
> "/.dz" <dz@discussions.microsoft.com> wrote in message
> news:1AC558F8-332E-4CEB-BEC5-2564EB1FFB00@microsoft.com...
> > Steve:
> > As before, thank you for the explanation of the relationship between the
> > 'null sessions' and the Computer Browser service -- one less source of
> > ambiguity for me to deal with. Unfortunately, for reasons related to 'job
> > security', I am not able to investigate the 'restrict anonymous access'
> > option at this time. However, if at some point in the near future I am
> > able
> > to, I will add my experience to this dialog.
> >
> > That having been said, and if you are still willing, I'd like to return to
> > the original response you provided and ask in detail about one of the
> > other
> > points -- disabling NETBIOS over tcp/ip. I'm fairly certain that I
> > understand the premise of 'name resolution' and you've indicated that as
> > long
> > as the file-share users reference the share with either a FQDN (or
> > equivalently, the workstation TCP/IP Advanced Properties DNS settings has
> > an
> > appropriate suffix in the list that results in a FQDN), name resolution
> > should proceed OK. Question: Does this imply that NETBIOS - from the
> > standpoint of file sharing - is only needed for name resolution? There's
> > no
> > other aspect to file sharing that is dependent upon NETBIOS?
> > ./dz
> >
> > "Steven L Umbach" wrote:
> >
> >> The browser service is just one and the most common use of null sessions.
> >> However disabling the browser service simply prevents the computer from
> >> becoming a master browser or backup browser. If you can change the
> >> security
> >> option for additional restrictions for anonymous access to be no access
> >> without explicit anonymous permissions you will prevent null connections
> >> though apparently you may still see anonymous logon events in the
> >> security
> >> log as I experienced. The KB article below explains more on how to do
> >> this
> >> but be sure to read the consequences first. --- Steve
> >>
> >> http://support.microsoft.com/?kbid=246261
> >>
> >> The following tasks are restricted when the RestrictAnonymous registry
> >> value
> >> is set to 2 on a Windows 2000-based domain controller: . Down-level
> >> member
> >> workstations or servers are not able to set up a netlogon secure channel.
> >> . Down-level domain controllers in trusting domains are not be able
> >> to
> >> set up a netlogon secure channel.
> >> . Microsoft Windows NT users are not able to change their passwords
> >> after they expire. Also, Macintosh users are not able to change their
> >> passwords at all.
> >> . The Browser service is not able to retrieve domain lists or
> >> server
> >> lists from backup browsers, master browsers or domain master browsers
> >> that
> >> are running on computers with the RestrictAnonymous registry value set to
> >> 2.
> >> Because of this, any program that relies on the Browser service does not
> >> function properly
> >>
> >>
> >> "/.dz" <dz@discussions.microsoft.com> wrote in message
> >> news:6D02852B-4580-422D-A4F1-81D7CC52C8FA@microsoft.com...
> >> > Again, thanks. Here's what I know now that I didn't prior to your
> >> > response --
> >> > Your version of the 'null session' command has two less ""s in it. And
> >> > that
> >> > makes it work! So now I can indeed verify that I am able to establish
> >> > a
> >> > null
> >> > session with my server; and 'yes' it apparently does log a 538 upon
> >> > session
> >> > termination. But allow me a further quesiton: Since I have the
> >> > 'Computer
> >> > Browser' service disabled on the server, why are 'null sessions' still
> >> > allowed? I was under the impression that null sessions only existed to
> >> > facilitate the 'enumeration' of resouces that the browsing capability
> >> > supports; and therefore by disabling the Computer Browser service I
> >> > would
> >> > effectively prevent 'null sessions' from occurring. ??
> >> >
> >> > "Steven L Umbach" wrote:
> >> >
> >> >> I am experiencing something different than you are [ as shown below].
> >> >> As
> >> >> long as the security option for additional restrictions for anonymous
> >> >> access
> >> >> is NOT set to no access without explicit anonymous permissions I am
> >> >> able
> >> >> to
> >> >> create a null session. When I do have no access without explicit
> >> >> anonymous
> >> >> permissions enabled I can not create a null session and I simply get a
> >> >> system error 5 has occurred - access is denied. Even when access was
> >> >> denied
> >> >> to my null session an Event ID 538 is recorded in the security log of
> >> >> my
> >> >> server for successful anonymous logoff which indicates that these
> >> >> events
> >> >> may
> >> >> be recorded even if a null session is denied. You might want to see if
> >> >> you
> >> >> have any current sessons to your server before you try null session
> >> >> with
> >> >> "
> >> >> net use " command and delete them if there are any and try again. I
> >> >> doubt
> >> >> Client for Microsoft Networks enabled on your server is causing the
> >> >> null
> >> >> sessions to be created to your server. If your server does not need to
> >> >> logon
> >> >> to a domain or access shares/resources on other computers then you
> >> >> should
> >> >> be
> >> >> able to diable it with no ill effect. A dedicated web server for
> >> >> instance
> >> >> would not need to use Client for Microsoft Networks. --- Steve
> >> >>
> >> >> D:\Documents and Settings\Steve>net use \\192.168.1.105\ipc$ "" /u:""
> >> >> The command completed successfully.
> >> >>
> >> >>
> >> >> D:\Documents and Settings\Steve>net use \\192.168.1.105\ipc$ "" /u:""
> >> >> System error 5 has occurred.
> >> >>
> >> >> Access is denied.
> >> >>
> >> >> Event Type: Success Audit
> >> >> Event Source: Security
> >> >> Event Category: Logon/Logoff
> >> >> Event ID: 538
> >> >> Date: 3/16/2005
> >> >> Time: 11:56:16 PM
> >> >> User: NT AUTHORITY\ANONYMOUS LOGON
> >> >> Computer: SERVER1-2000
> >> >> Description:
> >> >> User Logoff:
> >> >> User Name: ANONYMOUS LOGON
> >> >> Domain: NT AUTHORITY
> >> >> Logon ID: (0x0,0x2CFBA3)
> >> >> Logon Type: 3
> >> >>
> >> >>
> >> >> "/.dz" <dz@discussions.microsoft.com> wrote in message
> >> >> news:1D63D35D-431D-4A78-83BD-AE4A2E8EE0D1@microsoft.com...
> >> >> > Steve:
> >> >> > First thanks very much for the response. I've noticed that your
> >> >> > name
> >> >> > is
> >> >> > on
> >> >> > a lot of the responses in this forum and I appreciate the help as
> >> >> > much
> >> >> > as
> >> >> > I'm
> >> >> > sure the other people do as well.
> >> >> >
> >> >> > So anytime you get tired of this thread, it will probably die -- but
> >> >> > I
> >> >> > will
> >> >> > continue to ask questions as long as you continue to respond.
> >> >> >
> >> >> > In your response, you mentioned 'null sessions'. In other articles
> >> >> > I've
> >> >> > read, there is a reference to using the statement [net use
> >> >> > \\servername\ipc$
> >> >> > """" /u:""] to check if null sessions are able to be created. When
> >> >> > I
> >> >> > attempted this statement from my workstation, targetting the
> >> >> > 'servername'
> >> >> > being discussed in this posting, I received the "Logon failure:
> >> >> > unknown
> >> >> > user
> >> >> > name or bad password" message at the workstation, and the server
> >> >> > logged
> >> >> > an
> >> >> > event 529 Logon failure, explicitly indicating my userid,
> >> >> > workstation,
> >> >> > and
> >> >> > domain. From this info, I'm assuming that the 'null sessions'
> >> >> > discussion
> >> >> > does not apply to my situation. Is that a valid conclusion? Also,
> >> >> > the
> >> >> > Computer Browser service is disabled (and has been since
> >> >> > installation)
> >> >> > on
> >> >> > the
> >> >> > server. Am I also 'on-track' here in that these two items are
> >> >> > directly
> >> >> > related? (That is, 'null sessions' are enabled - i.e., required -
> >> >> > for
> >> >> > the
> >> >> > Computer Browser service to function)
> >> >> >
> >> >> > I want to ask about the other items in your response as well, but to
> >> >> > keep
> >> >> > the dialog within reasonable bounds, I'm electing to go through it
> >> >> > one
> >> >> > item
> >> >> > at a time --- starting (I think) with the most clearcut.
> >> >> >
> >> >> > Also in this thread, I need to about the 'Client for Microsoft
> >> >> > Networks' .
> >> >> > The server has this protocol enabled. Two further questions: a)
> >> >> > This
> >> >> > client
> >> >> > is only necessary if the computer (the server in this case) wants to
> >> >> > access
> >> >> > other NETBIOS resources on the net; it is not required for other
> >> >> > computers
> >> >> > on
> >> >> > the net to reach its (the server's) resources. Is this correct? b)
> >> >> > the
> >> >> > 'Client for Microsoft Networks' is not responsible for the 538
> >> >> > logout
> >> >> > events
> >> >> > mentioned in the original post?
> >> >> >
> >> >> > Any further dialog is greatly appreciated.
> >> >> > ./dz
> >> >> >
> >> >> > "Steven L Umbach" wrote:
> >> >> >
> >> >> >> It is common to see those Events on computers using Windows
> >> >> >> networking
> >> >> >> and
> >> >> >> that have file and print sharing and Client for Microsoft networks
> >> >> >> enabled.
> >> >> >> Those often are null sessions used by the computer browser service.
> >> >> >> While
> >> >> >> null sessions can be used to enumerate users, groups, and shares
> >> >> >> you
> >> >> >> can
> >> >> >> mitigate the risk by using a firewall to prevent internet access to
> >> >> >> null
> >> >> >> sessions, enforcing strong passwords on your network, and making
> >> >> >> sure
> >> >> >> your
> >> >> >> share/folder permissions only allow authorized users access.
> >> >> >>
> >> >> >> There are things you can do to reduce there occurrence as ling as
> >> >> >> the
> >> >> >> changes do not interfere with your network access for users. For
> >> >> >> instance
> >> >> >> disabling netbios over tcp/ip, disabling the computer browser
> >> >> >> service,
> >> >> >> and
> >> >> >> configuring the security option for "additional restrictions for
> >> >> >> anonymous
> >> >> >> access" to be " no access without explicit anonymous permissions".
> >> >> >> If
> >> >> >> you
> >> >> >> disable netbios over tcp/ip on a computer it will no longer show in
> >> >> >> or
> >> >> >> be
> >> >> >> able to use My Network Places but access to shares can still be
> >> >> >> done
> >> >> >> via
> >> >> >> fully qualified domain name or possibly even netbios name as long
> >> >> >> as
> >> >> >> dns
> >> >> >> can
> >> >> >> resolve the non FQDN by appending parent suffix to the request. The
> >> >> >> link
> >> >> >> below explains anonymous access more and the security option to
> >> >> >> restrict
> >> >> >> it
> >> >> >> along with possible consequences of doing such. --- Steve
> >> >> >>
> >> >> >> http://support.microsoft.com/?kbid=246261
> >> >> >>
> >> >> >> "/.dz" </.dz@discussions.microsoft.com> wrote in message
> >> >> >> news:480AE832-9FE3-4740-A265-6F6CA5A898FD@microsoft.com...
> >> >> >> > The security event log on our W2K, SP4 server has hundreds of the
> >> >> >> > above
> >> >> >> > messages in it. There are no associated 'logon' events, just the
> >> >> >> > 'logoff'
> >> >> >> > events.
> >> >> >> >
> >> >> >> > File and Print sharing is enabled on this server.
> >> >> >> >
> >> >> >> > There are several published file shares (all hidden); and there
> >> >> >> > are
> >> >> >> > individuals who are authorized to use those shares. The security
> >> >> >> > log
> >> >> >> > does
> >> >> >> > contain 540/538 'pairs' that reflect the credentials of these
> >> >> >> > known
> >> >> >> > users
> >> >> >> > (user/domain). (These are also 'Logon Type 3') But the number of
> >> >> >> > 538
> >> >> >> > NT
> >> >> >> > AUTHORITY/ANONYMOUS LOGON events absolutely dwarfs the number of
> >> >> >> > "known
> >> >> >> > user"
> >> >> >> > logon/logoff events.
> >> >> >> >
> >> >> >> > The server itself is not a domain controller. It was until
> >> >> >> > recently
> >> >> >> > a
> >> >> >> > member of a NT domain, and now is under AD (I don't know how to
> >> >> >> > state
> >> >> >> > that
> >> >> >> > with any accuracy). 'Known user' logon/logoff events are
> >> >> >> > present
> >> >> >> > for
> >> >> >> > both
> >> >> >> > the 'older' NT domain, and the newer 'AD' whatever).
> >> >> >> >
> >> >> >> > I've scoured newsgroups and the MS web site without any luck
> >> >> >> > whatsoever.
> >> >> >> > Any feedback would be greatly appreciated.
> >> >> >> >
> >> >> >>
> >> >> >>
> >> >> >>
> >> >>
> >> >>
> >> >>
> >>
> >>
> >>
>
>
>
Anonymous
a b 8 Security
March 23, 2005 2:01:32 AM

Archived from groups: microsoft.public.win2000.security (More info?)

No problem.

Yes UDP is used to contact Wins servers and for broadcast netbios name
resolution if a Wins server is not used. Port 138 UDP is mostly used for
traffic that maintains the browse list that is what My Network Places uses
for network browsing. Traffic such as browse announcements, requests for
browser master, and browser elections use that port. Port 139 TCP is used a
lot for file and print sharing and is a port where the actual data transfer
takes place. A real good way to learn all this is with a packet sniffer.
Netmon is built into server editions of Windows but I like Ethereal a lot
better and it is free. The link below contains some basics on NBT. ---
Steve

http://www.keyfocus.net/kfsensor/help/AdminGuide/adm_NB...
http://support.microsoft.com/default.aspx?scid=kb;en-us;832017 --- ports
used by Windows.


"/.dz" <dz@discussions.microsoft.com> wrote in message
news:64CF1392-1184-4248-AA5E-05C0EBD35316@microsoft.com...
> Steve:
> I did not lose interest -- but I did have other things to attend to. This
> particular thread has become almost a hobby with me -- so you are
> forewarned;
> I will probably keep going until you tire of my questions; and of course,
> I
> appreciate all the information you've already provided regardless of
> whether
> you continue or not.
>
> But if you elected to continue ...
>
> When I read the last response, this is what I 'hear', right or wrong. UDP
> 137 is used by the client to contact a WINS server for name resolution.
> UDP
> 138 I don't understand, unless it's a port simply to listen for responses
> to
> requests issued via UDP 137 and/or broadcasts. TCP 139 I think I
> understand
> -- using NETSTAT I can 'see' a couple of workstations have ESTABLISHED
> connections to TCP 139 on my server and recognize the 'foreign' IP address
> as
> valid users of the system.
>
> [By the way, if you happen to know of a relatively concise article that
> describes the NetBIOS protocol, perhaps replete with dialog examples, I'd
> be
> interested ....]
>
> ./dz
>
>
> "Steven L Umbach" wrote:
>
>> First off disabling netbios over tcp/ip will not stop null sessions but
>> it
>> may reduce them. Netbios over tcp/ip is legacy [W98/NT4.0, etc] file and
>> print sharing that uses ports 137UDP/138UDP/139TCP for netbios naming,
>> transport, and session services. It will use broadcasts only, if a wins
>> server is not available. NBT [net bios over tcp/ip] uses port 137 UDP for
>> naming for client to contact wins server, 138 UDP for browse list
>> maintenance, and 139 TCP for actual file sharing. Legacy clients can only
>> use NBT and if disabled will not be able to do any name resolution,
>> browsing, or file sharing.
>>
>> Windows 2000/XP/2003 can use either NBT or CIFS [port 445TCP] and also
>> DNS
>> for name resolution of course. If NBT is disabled then Windows
>> 2000/XP/2003
>> will use DNS and port 445TCP for file and print sharing. A Windows
>> 2000/XP
>> Pro/2003 domain computer will always use dns name resolution first for
>> any
>> name resolution request. It will append parent domain suffix [or whatever
>> you configure] to a non FQDN request. Windows 2000/XP/2003 in a workgroup
>> however will use NBT first for name resolution for a non FQDN if it is
>> enabled.
>>
>> Care should be taken before disabling NBT to make sure no computers or
>> applications need to use it to refer to computers by name. If it is
>> disabled
>> then for 2000/XP/2003 you can still use names to refer to file shares.
>> DNS
>> FQDN will work and "flat" computer names may work if your dns can resolve
>> the names by appending suffixes for domain computers. For non domain
>> computers you are best using only FQDN when referring to computer names
>> if
>> NBT is disabled. While NBT is legacy technology it still is widely used
>> in
>> most of today's networks and still is required in some cases such as for
>> certain configurations with Exchange and clusters I believe. --- Steve
>>
>>
>> "/.dz" <dz@discussions.microsoft.com> wrote in message
>> news:1AC558F8-332E-4CEB-BEC5-2564EB1FFB00@microsoft.com...
>> > Steve:
>> > As before, thank you for the explanation of the relationship between
>> > the
>> > 'null sessions' and the Computer Browser service -- one less source of
>> > ambiguity for me to deal with. Unfortunately, for reasons related to
>> > 'job
>> > security', I am not able to investigate the 'restrict anonymous access'
>> > option at this time. However, if at some point in the near future I am
>> > able
>> > to, I will add my experience to this dialog.
>> >
>> > That having been said, and if you are still willing, I'd like to return
>> > to
>> > the original response you provided and ask in detail about one of the
>> > other
>> > points -- disabling NETBIOS over tcp/ip. I'm fairly certain that I
>> > understand the premise of 'name resolution' and you've indicated that
>> > as
>> > long
>> > as the file-share users reference the share with either a FQDN (or
>> > equivalently, the workstation TCP/IP Advanced Properties DNS settings
>> > has
>> > an
>> > appropriate suffix in the list that results in a FQDN), name resolution
>> > should proceed OK. Question: Does this imply that NETBIOS - from the
>> > standpoint of file sharing - is only needed for name resolution?
>> > There's
>> > no
>> > other aspect to file sharing that is dependent upon NETBIOS?
>> > ./dz
>> >
>> > "Steven L Umbach" wrote:
>> >
>> >> The browser service is just one and the most common use of null
>> >> sessions.
>> >> However disabling the browser service simply prevents the computer
>> >> from
>> >> becoming a master browser or backup browser. If you can change the
>> >> security
>> >> option for additional restrictions for anonymous access to be no
>> >> access
>> >> without explicit anonymous permissions you will prevent null
>> >> connections
>> >> though apparently you may still see anonymous logon events in the
>> >> security
>> >> log as I experienced. The KB article below explains more on how to do
>> >> this
>> >> but be sure to read the consequences first. --- Steve
>> >>
>> >> http://support.microsoft.com/?kbid=246261
>> >>
>> >> The following tasks are restricted when the RestrictAnonymous registry
>> >> value
>> >> is set to 2 on a Windows 2000-based domain controller: . Down-level
>> >> member
>> >> workstations or servers are not able to set up a netlogon secure
>> >> channel.
>> >> . Down-level domain controllers in trusting domains are not be
>> >> able
>> >> to
>> >> set up a netlogon secure channel.
>> >> . Microsoft Windows NT users are not able to change their
>> >> passwords
>> >> after they expire. Also, Macintosh users are not able to change their
>> >> passwords at all.
>> >> . The Browser service is not able to retrieve domain lists or
>> >> server
>> >> lists from backup browsers, master browsers or domain master browsers
>> >> that
>> >> are running on computers with the RestrictAnonymous registry value set
>> >> to
>> >> 2.
>> >> Because of this, any program that relies on the Browser service does
>> >> not
>> >> function properly
>> >>
>> >>
>> >> "/.dz" <dz@discussions.microsoft.com> wrote in message
>> >> news:6D02852B-4580-422D-A4F1-81D7CC52C8FA@microsoft.com...
>> >> > Again, thanks. Here's what I know now that I didn't prior to your
>> >> > response --
>> >> > Your version of the 'null session' command has two less ""s in it.
>> >> > And
>> >> > that
>> >> > makes it work! So now I can indeed verify that I am able to
>> >> > establish
>> >> > a
>> >> > null
>> >> > session with my server; and 'yes' it apparently does log a 538 upon
>> >> > session
>> >> > termination. But allow me a further quesiton: Since I have the
>> >> > 'Computer
>> >> > Browser' service disabled on the server, why are 'null sessions'
>> >> > still
>> >> > allowed? I was under the impression that null sessions only existed
>> >> > to
>> >> > facilitate the 'enumeration' of resouces that the browsing
>> >> > capability
>> >> > supports; and therefore by disabling the Computer Browser service I
>> >> > would
>> >> > effectively prevent 'null sessions' from occurring. ??
>> >> >
>> >> > "Steven L Umbach" wrote:
>> >> >
>> >> >> I am experiencing something different than you are [ as shown
>> >> >> below].
>> >> >> As
>> >> >> long as the security option for additional restrictions for
>> >> >> anonymous
>> >> >> access
>> >> >> is NOT set to no access without explicit anonymous permissions I am
>> >> >> able
>> >> >> to
>> >> >> create a null session. When I do have no access without explicit
>> >> >> anonymous
>> >> >> permissions enabled I can not create a null session and I simply
>> >> >> get a
>> >> >> system error 5 has occurred - access is denied. Even when access
>> >> >> was
>> >> >> denied
>> >> >> to my null session an Event ID 538 is recorded in the security log
>> >> >> of
>> >> >> my
>> >> >> server for successful anonymous logoff which indicates that these
>> >> >> events
>> >> >> may
>> >> >> be recorded even if a null session is denied. You might want to see
>> >> >> if
>> >> >> you
>> >> >> have any current sessons to your server before you try null
>> >> >> session
>> >> >> with
>> >> >> "
>> >> >> net use " command and delete them if there are any and try again. I
>> >> >> doubt
>> >> >> Client for Microsoft Networks enabled on your server is causing the
>> >> >> null
>> >> >> sessions to be created to your server. If your server does not need
>> >> >> to
>> >> >> logon
>> >> >> to a domain or access shares/resources on other computers then you
>> >> >> should
>> >> >> be
>> >> >> able to diable it with no ill effect. A dedicated web server for
>> >> >> instance
>> >> >> would not need to use Client for Microsoft Networks. --- Steve
>> >> >>
>> >> >> D:\Documents and Settings\Steve>net use \\192.168.1.105\ipc$ ""
>> >> >> /u:""
>> >> >> The command completed successfully.
>> >> >>
>> >> >>
>> >> >> D:\Documents and Settings\Steve>net use \\192.168.1.105\ipc$ ""
>> >> >> /u:""
>> >> >> System error 5 has occurred.
>> >> >>
>> >> >> Access is denied.
>> >> >>
>> >> >> Event Type: Success Audit
>> >> >> Event Source: Security
>> >> >> Event Category: Logon/Logoff
>> >> >> Event ID: 538
>> >> >> Date: 3/16/2005
>> >> >> Time: 11:56:16 PM
>> >> >> User: NT AUTHORITY\ANONYMOUS LOGON
>> >> >> Computer: SERVER1-2000
>> >> >> Description:
>> >> >> User Logoff:
>> >> >> User Name: ANONYMOUS LOGON
>> >> >> Domain: NT AUTHORITY
>> >> >> Logon ID: (0x0,0x2CFBA3)
>> >> >> Logon Type: 3
>> >> >>
>> >> >>
>> >> >> "/.dz" <dz@discussions.microsoft.com> wrote in message
>> >> >> news:1D63D35D-431D-4A78-83BD-AE4A2E8EE0D1@microsoft.com...
>> >> >> > Steve:
>> >> >> > First thanks very much for the response. I've noticed that your
>> >> >> > name
>> >> >> > is
>> >> >> > on
>> >> >> > a lot of the responses in this forum and I appreciate the help as
>> >> >> > much
>> >> >> > as
>> >> >> > I'm
>> >> >> > sure the other people do as well.
>> >> >> >
>> >> >> > So anytime you get tired of this thread, it will probably die --
>> >> >> > but
>> >> >> > I
>> >> >> > will
>> >> >> > continue to ask questions as long as you continue to respond.
>> >> >> >
>> >> >> > In your response, you mentioned 'null sessions'. In other
>> >> >> > articles
>> >> >> > I've
>> >> >> > read, there is a reference to using the statement [net use
>> >> >> > \\servername\ipc$
>> >> >> > """" /u:""] to check if null sessions are able to be created.
>> >> >> > When
>> >> >> > I
>> >> >> > attempted this statement from my workstation, targetting the
>> >> >> > 'servername'
>> >> >> > being discussed in this posting, I received the "Logon failure:
>> >> >> > unknown
>> >> >> > user
>> >> >> > name or bad password" message at the workstation, and the server
>> >> >> > logged
>> >> >> > an
>> >> >> > event 529 Logon failure, explicitly indicating my userid,
>> >> >> > workstation,
>> >> >> > and
>> >> >> > domain. From this info, I'm assuming that the 'null sessions'
>> >> >> > discussion
>> >> >> > does not apply to my situation. Is that a valid conclusion?
>> >> >> > Also,
>> >> >> > the
>> >> >> > Computer Browser service is disabled (and has been since
>> >> >> > installation)
>> >> >> > on
>> >> >> > the
>> >> >> > server. Am I also 'on-track' here in that these two items are
>> >> >> > directly
>> >> >> > related? (That is, 'null sessions' are enabled - i.e.,
>> >> >> > required -
>> >> >> > for
>> >> >> > the
>> >> >> > Computer Browser service to function)
>> >> >> >
>> >> >> > I want to ask about the other items in your response as well, but
>> >> >> > to
>> >> >> > keep
>> >> >> > the dialog within reasonable bounds, I'm electing to go through
>> >> >> > it
>> >> >> > one
>> >> >> > item
>> >> >> > at a time --- starting (I think) with the most clearcut.
>> >> >> >
>> >> >> > Also in this thread, I need to about the 'Client for Microsoft
>> >> >> > Networks' .
>> >> >> > The server has this protocol enabled. Two further questions: a)
>> >> >> > This
>> >> >> > client
>> >> >> > is only necessary if the computer (the server in this case) wants
>> >> >> > to
>> >> >> > access
>> >> >> > other NETBIOS resources on the net; it is not required for other
>> >> >> > computers
>> >> >> > on
>> >> >> > the net to reach its (the server's) resources. Is this correct?
>> >> >> > b)
>> >> >> > the
>> >> >> > 'Client for Microsoft Networks' is not responsible for the 538
>> >> >> > logout
>> >> >> > events
>> >> >> > mentioned in the original post?
>> >> >> >
>> >> >> > Any further dialog is greatly appreciated.
>> >> >> > ./dz
>> >> >> >
>> >> >> > "Steven L Umbach" wrote:
>> >> >> >
>> >> >> >> It is common to see those Events on computers using Windows
>> >> >> >> networking
>> >> >> >> and
>> >> >> >> that have file and print sharing and Client for Microsoft
>> >> >> >> networks
>> >> >> >> enabled.
>> >> >> >> Those often are null sessions used by the computer browser
>> >> >> >> service.
>> >> >> >> While
>> >> >> >> null sessions can be used to enumerate users, groups, and shares
>> >> >> >> you
>> >> >> >> can
>> >> >> >> mitigate the risk by using a firewall to prevent internet access
>> >> >> >> to
>> >> >> >> null
>> >> >> >> sessions, enforcing strong passwords on your network, and making
>> >> >> >> sure
>> >> >> >> your
>> >> >> >> share/folder permissions only allow authorized users access.
>> >> >> >>
>> >> >> >> There are things you can do to reduce there occurrence as ling
>> >> >> >> as
>> >> >> >> the
>> >> >> >> changes do not interfere with your network access for users. For
>> >> >> >> instance
>> >> >> >> disabling netbios over tcp/ip, disabling the computer browser
>> >> >> >> service,
>> >> >> >> and
>> >> >> >> configuring the security option for "additional restrictions for
>> >> >> >> anonymous
>> >> >> >> access" to be " no access without explicit anonymous
>> >> >> >> permissions".
>> >> >> >> If
>> >> >> >> you
>> >> >> >> disable netbios over tcp/ip on a computer it will no longer show
>> >> >> >> in
>> >> >> >> or
>> >> >> >> be
>> >> >> >> able to use My Network Places but access to shares can still be
>> >> >> >> done
>> >> >> >> via
>> >> >> >> fully qualified domain name or possibly even netbios name as
>> >> >> >> long
>> >> >> >> as
>> >> >> >> dns
>> >> >> >> can
>> >> >> >> resolve the non FQDN by appending parent suffix to the request.
>> >> >> >> The
>> >> >> >> link
>> >> >> >> below explains anonymous access more and the security option to
>> >> >> >> restrict
>> >> >> >> it
>> >> >> >> along with possible consequences of doing such. --- Steve
>> >> >> >>
>> >> >> >> http://support.microsoft.com/?kbid=246261
>> >> >> >>
>> >> >> >> "/.dz" </.dz@discussions.microsoft.com> wrote in message
>> >> >> >> news:480AE832-9FE3-4740-A265-6F6CA5A898FD@microsoft.com...
>> >> >> >> > The security event log on our W2K, SP4 server has hundreds of
>> >> >> >> > the
>> >> >> >> > above
>> >> >> >> > messages in it. There are no associated 'logon' events, just
>> >> >> >> > the
>> >> >> >> > 'logoff'
>> >> >> >> > events.
>> >> >> >> >
>> >> >> >> > File and Print sharing is enabled on this server.
>> >> >> >> >
>> >> >> >> > There are several published file shares (all hidden); and
>> >> >> >> > there
>> >> >> >> > are
>> >> >> >> > individuals who are authorized to use those shares. The
>> >> >> >> > security
>> >> >> >> > log
>> >> >> >> > does
>> >> >> >> > contain 540/538 'pairs' that reflect the credentials of these
>> >> >> >> > known
>> >> >> >> > users
>> >> >> >> > (user/domain). (These are also 'Logon Type 3') But the number
>> >> >> >> > of
>> >> >> >> > 538
>> >> >> >> > NT
>> >> >> >> > AUTHORITY/ANONYMOUS LOGON events absolutely dwarfs the number
>> >> >> >> > of
>> >> >> >> > "known
>> >> >> >> > user"
>> >> >> >> > logon/logoff events.
>> >> >> >> >
>> >> >> >> > The server itself is not a domain controller. It was until
>> >> >> >> > recently
>> >> >> >> > a
>> >> >> >> > member of a NT domain, and now is under AD (I don't know how
>> >> >> >> > to
>> >> >> >> > state
>> >> >> >> > that
>> >> >> >> > with any accuracy). 'Known user' logon/logoff events are
>> >> >> >> > present
>> >> >> >> > for
>> >> >> >> > both
>> >> >> >> > the 'older' NT domain, and the newer 'AD' whatever).
>> >> >> >> >
>> >> >> >> > I've scoured newsgroups and the MS web site without any luck
>> >> >> >> > whatsoever.
>> >> >> >> > Any feedback would be greatly appreciated.
>> >> >> >> >
>> >> >> >>
>> >> >> >>
>> >> >> >>
>> >> >>
>> >> >>
>> >> >>
>> >>
>> >>
>> >>
>>
>>
>>
Anonymous
a b 8 Security
March 23, 2005 11:11:13 AM

Archived from groups: microsoft.public.win2000.security (More info?)

Steve:
Thanks very much for this entire dialog. I'm gonna take some time to read
the references you provided -- which because of other priorities might take a
while. In any case, I'm most appreciative for all the feedback. I won't
promise that I'll let this thread die altogether -- but it's hard to say at
the moment. You've given me more than enough to think on for a while and
once I feel comfortable with the protocol dialogs, I might get back to the
original 'security' concern.

And, believe it or not, I had found Ethereal via another contact some months
ago -- but it isn't something that I get an opportunity to use very often.
And when I have 'dabbled', I've been a bit confused by the filtering
mechanism, so I end up with a lot more traffic being captured than I'm able
to comprehend.

At some point in the future, I might even ask you about the filter settings
you might employ to sniff NetBIOS traffic. In that regard, and since it
could conceivably be of interest to audiences on newsgroups more
'network-centric', are you a regualr contributor on any other newsgroup(s) -
one(s) that are in fact related to the networking?
../dz

"Steven L Umbach" wrote:

> No problem.
>
> Yes UDP is used to contact Wins servers and for broadcast netbios name
> resolution if a Wins server is not used. Port 138 UDP is mostly used for
> traffic that maintains the browse list that is what My Network Places uses
> for network browsing. Traffic such as browse announcements, requests for
> browser master, and browser elections use that port. Port 139 TCP is used a
> lot for file and print sharing and is a port where the actual data transfer
> takes place. A real good way to learn all this is with a packet sniffer.
> Netmon is built into server editions of Windows but I like Ethereal a lot
> better and it is free. The link below contains some basics on NBT. ---
> Steve
>
> http://www.keyfocus.net/kfsensor/help/AdminGuide/adm_NB...
> http://support.microsoft.com/default.aspx?scid=kb;en-us;832017 --- ports
> used by Windows.
>
>
> "/.dz" <dz@discussions.microsoft.com> wrote in message
> news:64CF1392-1184-4248-AA5E-05C0EBD35316@microsoft.com...
> > Steve:
> > I did not lose interest -- but I did have other things to attend to. This
> > particular thread has become almost a hobby with me -- so you are
> > forewarned;
> > I will probably keep going until you tire of my questions; and of course,
> > I
> > appreciate all the information you've already provided regardless of
> > whether
> > you continue or not.
> >
> > But if you elected to continue ...
> >
> > When I read the last response, this is what I 'hear', right or wrong. UDP
> > 137 is used by the client to contact a WINS server for name resolution.
> > UDP
> > 138 I don't understand, unless it's a port simply to listen for responses
> > to
> > requests issued via UDP 137 and/or broadcasts. TCP 139 I think I
> > understand
> > -- using NETSTAT I can 'see' a couple of workstations have ESTABLISHED
> > connections to TCP 139 on my server and recognize the 'foreign' IP address
> > as
> > valid users of the system.
> >
> > [By the way, if you happen to know of a relatively concise article that
> > describes the NetBIOS protocol, perhaps replete with dialog examples, I'd
> > be
> > interested ....]
> >
> > ./dz
> >
> >
> > "Steven L Umbach" wrote:
> >
> >> First off disabling netbios over tcp/ip will not stop null sessions but
> >> it
> >> may reduce them. Netbios over tcp/ip is legacy [W98/NT4.0, etc] file and
> >> print sharing that uses ports 137UDP/138UDP/139TCP for netbios naming,
> >> transport, and session services. It will use broadcasts only, if a wins
> >> server is not available. NBT [net bios over tcp/ip] uses port 137 UDP for
> >> naming for client to contact wins server, 138 UDP for browse list
> >> maintenance, and 139 TCP for actual file sharing. Legacy clients can only
> >> use NBT and if disabled will not be able to do any name resolution,
> >> browsing, or file sharing.
> >>
> >> Windows 2000/XP/2003 can use either NBT or CIFS [port 445TCP] and also
> >> DNS
> >> for name resolution of course. If NBT is disabled then Windows
> >> 2000/XP/2003
> >> will use DNS and port 445TCP for file and print sharing. A Windows
> >> 2000/XP
> >> Pro/2003 domain computer will always use dns name resolution first for
> >> any
> >> name resolution request. It will append parent domain suffix [or whatever
> >> you configure] to a non FQDN request. Windows 2000/XP/2003 in a workgroup
> >> however will use NBT first for name resolution for a non FQDN if it is
> >> enabled.
> >>
> >> Care should be taken before disabling NBT to make sure no computers or
> >> applications need to use it to refer to computers by name. If it is
> >> disabled
> >> then for 2000/XP/2003 you can still use names to refer to file shares.
> >> DNS
> >> FQDN will work and "flat" computer names may work if your dns can resolve
> >> the names by appending suffixes for domain computers. For non domain
> >> computers you are best using only FQDN when referring to computer names
> >> if
> >> NBT is disabled. While NBT is legacy technology it still is widely used
> >> in
> >> most of today's networks and still is required in some cases such as for
> >> certain configurations with Exchange and clusters I believe. --- Steve
> >>
> >>
> >> "/.dz" <dz@discussions.microsoft.com> wrote in message
> >> news:1AC558F8-332E-4CEB-BEC5-2564EB1FFB00@microsoft.com...
> >> > Steve:
> >> > As before, thank you for the explanation of the relationship between
> >> > the
> >> > 'null sessions' and the Computer Browser service -- one less source of
> >> > ambiguity for me to deal with. Unfortunately, for reasons related to
> >> > 'job
> >> > security', I am not able to investigate the 'restrict anonymous access'
> >> > option at this time. However, if at some point in the near future I am
> >> > able
> >> > to, I will add my experience to this dialog.
> >> >
> >> > That having been said, and if you are still willing, I'd like to return
> >> > to
> >> > the original response you provided and ask in detail about one of the
> >> > other
> >> > points -- disabling NETBIOS over tcp/ip. I'm fairly certain that I
> >> > understand the premise of 'name resolution' and you've indicated that
> >> > as
> >> > long
> >> > as the file-share users reference the share with either a FQDN (or
> >> > equivalently, the workstation TCP/IP Advanced Properties DNS settings
> >> > has
> >> > an
> >> > appropriate suffix in the list that results in a FQDN), name resolution
> >> > should proceed OK. Question: Does this imply that NETBIOS - from the
> >> > standpoint of file sharing - is only needed for name resolution?
> >> > There's
> >> > no
> >> > other aspect to file sharing that is dependent upon NETBIOS?
> >> > ./dz
> >> >
> >> > "Steven L Umbach" wrote:
> >> >
> >> >> The browser service is just one and the most common use of null
> >> >> sessions.
> >> >> However disabling the browser service simply prevents the computer
> >> >> from
> >> >> becoming a master browser or backup browser. If you can change the
> >> >> security
> >> >> option for additional restrictions for anonymous access to be no
> >> >> access
> >> >> without explicit anonymous permissions you will prevent null
> >> >> connections
> >> >> though apparently you may still see anonymous logon events in the
> >> >> security
> >> >> log as I experienced. The KB article below explains more on how to do
> >> >> this
> >> >> but be sure to read the consequences first. --- Steve
> >> >>
> >> >> http://support.microsoft.com/?kbid=246261
> >> >>
> >> >> The following tasks are restricted when the RestrictAnonymous registry
> >> >> value
> >> >> is set to 2 on a Windows 2000-based domain controller: . Down-level
> >> >> member
> >> >> workstations or servers are not able to set up a netlogon secure
> >> >> channel.
> >> >> . Down-level domain controllers in trusting domains are not be
> >> >> able
> >> >> to
> >> >> set up a netlogon secure channel.
> >> >> . Microsoft Windows NT users are not able to change their
> >> >> passwords
> >> >> after they expire. Also, Macintosh users are not able to change their
> >> >> passwords at all.
> >> >> . The Browser service is not able to retrieve domain lists or
> >> >> server
> >> >> lists from backup browsers, master browsers or domain master browsers
> >> >> that
> >> >> are running on computers with the RestrictAnonymous registry value set
> >> >> to
> >> >> 2.
> >> >> Because of this, any program that relies on the Browser service does
> >> >> not
> >> >> function properly
> >> >>
> >> >>
> >> >> "/.dz" <dz@discussions.microsoft.com> wrote in message
> >> >> news:6D02852B-4580-422D-A4F1-81D7CC52C8FA@microsoft.com...
> >> >> > Again, thanks. Here's what I know now that I didn't prior to your
> >> >> > response --
> >> >> > Your version of the 'null session' command has two less ""s in it.
> >> >> > And
> >> >> > that
> >> >> > makes it work! So now I can indeed verify that I am able to
> >> >> > establish
> >> >> > a
> >> >> > null
> >> >> > session with my server; and 'yes' it apparently does log a 538 upon
> >> >> > session
> >> >> > termination. But allow me a further quesiton: Since I have the
> >> >> > 'Computer
> >> >> > Browser' service disabled on the server, why are 'null sessions'
> >> >> > still
> >> >> > allowed? I was under the impression that null sessions only existed
> >> >> > to
> >> >> > facilitate the 'enumeration' of resouces that the browsing
> >> >> > capability
> >> >> > supports; and therefore by disabling the Computer Browser service I
> >> >> > would
> >> >> > effectively prevent 'null sessions' from occurring. ??
> >> >> >
> >> >> > "Steven L Umbach" wrote:
> >> >> >
> >> >> >> I am experiencing something different than you are [ as shown
> >> >> >> below].
> >> >> >> As
> >> >> >> long as the security option for additional restrictions for
> >> >> >> anonymous
> >> >> >> access
> >> >> >> is NOT set to no access without explicit anonymous permissions I am
> >> >> >> able
> >> >> >> to
> >> >> >> create a null session. When I do have no access without explicit
> >> >> >> anonymous
> >> >> >> permissions enabled I can not create a null session and I simply
> >> >> >> get a
> >> >> >> system error 5 has occurred - access is denied. Even when access
> >> >> >> was
> >> >> >> denied
> >> >> >> to my null session an Event ID 538 is recorded in the security log
> >> >> >> of
> >> >> >> my
> >> >> >> server for successful anonymous logoff which indicates that these
> >> >> >> events
> >> >> >> may
> >> >> >> be recorded even if a null session is denied. You might want to see
> >> >> >> if
> >> >> >> you
> >> >> >> have any current sessons to your server before you try null
> >> >> >> session
> >> >> >> with
> >> >> >> "
> >> >> >> net use " command and delete them if there are any and try again. I
> >> >> >> doubt
> >> >> >> Client for Microsoft Networks enabled on your server is causing the
> >> >> >> null
> >> >> >> sessions to be created to your server. If your server does not need
> >> >> >> to
> >> >> >> logon
> >> >> >> to a domain or access shares/resources on other computers then you
> >> >> >> should
> >> >> >> be
> >> >> >> able to diable it with no ill effect. A dedicated web server for
> >> >> >> instance
> >> >> >> would not need to use Client for Microsoft Networks. --- Steve
> >> >> >>
> >> >> >> D:\Documents and Settings\Steve>net use \\192.168.1.105\ipc$ ""
> >> >> >> /u:""
> >> >> >> The command completed successfully.
> >> >> >>
> >> >> >>
> >> >> >> D:\Documents and Settings\Steve>net use \\192.168.1.105\ipc$ ""
> >> >> >> /u:""
> >> >> >> System error 5 has occurred.
> >> >> >>
> >> >> >> Access is denied.
> >> >> >>
> >> >> >> Event Type: Success Audit
> >> >> >> Event Source: Security
> >> >> >> Event Category: Logon/Logoff
> >> >> >> Event ID: 538
> >> >> >> Date: 3/16/2005
> >> >> >> Time: 11:56:16 PM
> >> >> >> User: NT AUTHORITY\ANONYMOUS LOGON
> >> >> >> Computer: SERVER1-2000
> >> >> >> Description:
> >> >> >> User Logoff:
> >> >> >> User Name: ANONYMOUS LOGON
> >> >> >> Domain: NT AUTHORITY
> >> >> >> Logon ID: (0x0,0x2CFBA3)
> >> >> >> Logon Type: 3
> >> >> >>
> >> >> >>
> >> >> >> "/.dz" <dz@discussions.microsoft.com> wrote in message
> >> >> >> news:1D63D35D-431D-4A78-83BD-AE4A2E8EE0D1@microsoft.com...
> >> >> >> > Steve:
> >> >> >> > First thanks very much for the response. I've noticed that your
> >> >> >> > name
> >> >> >> > is
> >> >> >> > on
> >> >> >> > a lot of the responses in this forum and I appreciate the help as
> >> >> >> > much
> >> >> >> > as
> >> >> >> > I'm
> >> >> >> > sure the other people do as well.
> >> >> >> >
> >> >> >> > So anytime you get tired of this thread, it will probably die --
> >> >> >> > but
> >> >> >> > I
> >> >> >> > will
> >> >> >> > continue to ask questions as long as you continue to respond.
> >> >> >> >
> >> >> >> > In your response, you mentioned 'null sessions'. In other
> >> >> >> > articles
> >> >> >> > I've
> >> >> >> > read, there is a reference to using the statement [net use
> >> >> >> > \\servername\ipc$
> >> >> >> > """" /u:""] to check if null sessions are able to be created.
> >> >> >> > When
> >> >> >> > I
> >> >> >> > attempted this statement from my workstation, targetting the
> >> >> >> > 'servername'
> >> >> >> > being discussed in this posting, I received the "Logon failure:
> >> >> >> > unknown
> >> >> >> > user
> >> >> >> > name or bad password" message at the workstation, and the server
> >> >> >> > logged
> >> >> >> > an
> >> >> >> > event 529 Logon failure, explicitly indicating my userid,
> >> >> >> > workstation,
> >> >> >> > and
> >> >> >> > domain. From this info, I'm assuming that the 'null sessions'
> >> >> >> > discussion
> >> >> >> > does not apply to my situation. Is that a valid conclusion?
> >> >> >> > Also,
> >> >> >> > the
> >> >> >> > Computer Browser service is disabled (and has been since
> >> >> >> > installation)
> >> >> >> > on
> >> >> >> > the
> >> >> >> > server. Am I also 'on-track' here in that these two items are
> >> >> >> > directly
> >> >> >> > related? (That is, 'null sessions' are enabled - i.e.,
> >> >> >> > required -
> >> >> >> > for
> >> >> >> > the
> >> >> >> > Computer Browser service to function)
> >> >> >> >
> >> >> >> > I want to ask about the other items in your response as well, but
> >> >> >> > to
> >> >> >> > keep
> >> >> >> > the dialog within reasonable bounds, I'm electing to go through
> >> >> >> > it
> >> >> >> > one
> >> >> >> > item
> >> >> >> > at a time --- starting (I think) with the most clearcut.
> >> >> >> >
> >> >> >> > Also in this thread, I need to about the 'Client for Microsoft
> >> >> >> > Networks' .
> >> >> >> > The server has this protocol enabled. Two further questions: a)
> >> >> >> > This
> >> >> >> > client
> >> >> >> > is only necessary if the computer (the server in this case) wants
> >> >> >> > to
> >> >> >> > access
> >> >> >> > other NETBIOS resources on the net; it is not required for other
> >> >> >> > computers
> >> >> >> > on
> >> >> >> > the net to reach its (the server's) resources. Is this correct?
> >> >> >> > b)
> >> >> >> > the
> >> >> >> > 'Client for Microsoft Networks' is not responsible for the 538
> >> >> >> > logout
> >> >> >> > events
> >> >> >> > mentioned in the original post?
> >> >> >> >
> >> >> >> > Any further dialog is greatly appreciated.
> >> >> >> > ./dz
> >> >> >> >
> >> >> >> > "Steven L Umbach" wrote:
> >> >> >> >
> >> >> >> >> It is common to see those Events on computers using Windows
> >> >> >> >> networking
> >> >> >> >> and
> >> >> >> >> that have file and print sharing and Client for Microsoft
> >> >> >> >> networks
> >> >> >> >> enabled.
> >> >> >> >> Those often are null sessions used by the computer browser
> >> >> >> >> service.
> >> >> >> >> While
> >> >> >> >> null sessions can be used to enumerate users, groups, and shares
> >> >> >> >> you
> >> >> >> >> can
> >> >> >> >> mitigate the risk by using a firewall to prevent internet access
> >> >> >> >> to
> >> >> >> >> null
> >> >> >> >> sessions, enforcing strong passwords on your network, and making
> >> >> >> >> sure
> >> >> >> >> your
> >> >> >> >> share/folder permissions only allow authorized users access.
> >> >> >> >>
> >> >> >> >> There are things you can do to reduce there occurrence as ling
> >> >> >> >> as
> >> >> >> >> the
> >> >> >> >> changes do not interfere with your network access for users. For
> >> >> >> >> instance
> >> >> >> >> disabling netbios over tcp/ip, disabling the computer browser
> >> >> >> >> service,
> >> >> >> >> and
> >> >> >> >> configuring the security option for "additional restrictions for
> >> >> >> >> anonymous
> >> >> >> >> access" to be " no access without explicit anonymous
> >> >> >> >> permissions".
> >> >> >> >> If
> >> >> >> >> you
> >> >> >> >> disable netbios over tcp/ip on a computer it will no longer show
> >> >> >> >> in
> >> >> >> >> or
> >> >> >> >> be
> >> >> >> >> able to use My Network Places but access to shares can still be
> >> >> >> >> done
> >> >> >> >> via
> >> >> >> >> fully qualified domain name or possibly even netbios name as
> >> >> >> >> long
> >> >> >> >> as
> >> >> >> >> dns
> >> >> >> >> can
> >> >> >> >> resolve the non FQDN by appending parent suffix to the request.
> >> >> >> >> The
> >> >> >> >> link
> >> >> >> >> below explains anonymous access more and the security option to
> >> >> >> >> restrict
> >> >> >> >> it
> >> >> >> >> along with possible consequences of doing such. --- Steve
> >> >> >> >>
> >> >> >> >> http://support.microsoft.com/?kbid=246261
> >> >> >> >>
> >> >> >> >> "/.dz" </.dz@discussions.microsoft.com> wrote in message
> >> >> >> >> news:480AE832-9FE3-4740-A265-6F6CA5A898FD@microsoft.com...
> >> >> >> >> > The security event log on our W2K, SP4 server has hundreds of
> >> >> >> >> > the
> >> >> >> >> > above
> >> >> >> >> > messages in it. There are no associated 'logon' events, just
> >> >> >> >> > the
> >> >> >> >> > 'logoff'
> >> >> >> >> > events.
> >> >> >> >> >
> >> >> >> >> > File and Print sharing is enabled on this server.
> >> >> >> >> >
> >> >> >> >> > There are several published file shares (all hidden); and
> >> >> >> >> > there
> >> >> >> >> > are
> >> >> >> >> > individuals who are authorized to use those shares. The
> >> >> >> >> > security
> >> >> >> >> > log
> >> >> >> >> > does
> >> >> >> >> > contain 540/538 'pairs' that reflect the credentials of these
> >> >> >> >> > known
> >> >> >> >> > users
> >> >> >> >> > (user/domain). (These are also 'Logon Type 3') But the number
> >> >> >> >> > of
> >> >> >> >> > 538
> >> >> >> >> > NT
> >> >> >> >> > AUTHORITY/ANONYMOUS LOGON events absolutely dwarfs the number
> >> >> >> >> > of
> >> >> >> >> > "known
> >> >> >> >> > user"
> >> >> >> >> > logon/logoff events.
> >> >> >> >> >
> >> >> >> >> > The server itself is not a domain controller. It was until
> >> >> >> >> > recently
> >> >> >> >> > a
> >> >> >> >> > member of a NT domain, and now is under AD (I don't know how
> >> >> >> >> > to
> >> >> >> >> > state
> >> >> >> >> > that
> >> >> >> >> > with any accuracy). 'Known user' logon/logoff events are
> >> >> >> >> > present
> >> >> >> >> > for
> >> >> >> >> > both
> >> >> >> >> > the 'older' NT domain, and the newer 'AD' whatever).
> >> >> >> >> >
> >> >> >> >> > I've scoured newsgroups and the MS web site without any luck
> >> >> >> >> > whatsoever.
> >> >> >> >> > Any feedback would be greatly appreciated.
> >> >> >> >> >
> >> >> >> >>
> >> >> >> >>
> >> >> >> >>
> >> >> >>
> >> >> >>
> >> >> >>
> >> >>
> >> >>
> >> >>
> >>
> >>
> >>
>
>
>
Anonymous
a b 8 Security
March 25, 2005 12:31:37 AM

Archived from groups: microsoft.public.win2000.security (More info?)

Sounds good. I am often on the Windows server networking newsgroup. I think
you will find Ethereal pretty easy to use once you play around with it for a
while and there is a lot of info for it if you search Google for whatever
you are trying to do. Creating capture filters go from being easy to
extremely complex. To capture netbios traffic simply use the capture filter
"port 137 or port 138 or port 139" without the quotes . --- Steve


"/.dz" <dz@discussions.microsoft.com> wrote in message
news:E20E4512-F89D-40F4-A5C8-E6632E88493B@microsoft.com...
> Steve:
> Thanks very much for this entire dialog. I'm gonna take some time to read
> the references you provided -- which because of other priorities might
> take a
> while. In any case, I'm most appreciative for all the feedback. I won't
> promise that I'll let this thread die altogether -- but it's hard to say
> at
> the moment. You've given me more than enough to think on for a while and
> once I feel comfortable with the protocol dialogs, I might get back to the
> original 'security' concern.
>
> And, believe it or not, I had found Ethereal via another contact some
> months
> ago -- but it isn't something that I get an opportunity to use very often.
> And when I have 'dabbled', I've been a bit confused by the filtering
> mechanism, so I end up with a lot more traffic being captured than I'm
> able
> to comprehend.
>
> At some point in the future, I might even ask you about the filter
> settings
> you might employ to sniff NetBIOS traffic. In that regard, and since it
> could conceivably be of interest to audiences on newsgroups more
> 'network-centric', are you a regualr contributor on any other
> newsgroup(s) -
> one(s) that are in fact related to the networking?
> ./dz
>
> "Steven L Umbach" wrote:
>
>> No problem.
>>
>> Yes UDP is used to contact Wins servers and for broadcast netbios name
>> resolution if a Wins server is not used. Port 138 UDP is mostly used for
>> traffic that maintains the browse list that is what My Network Places
>> uses
>> for network browsing. Traffic such as browse announcements, requests for
>> browser master, and browser elections use that port. Port 139 TCP is used
>> a
>> lot for file and print sharing and is a port where the actual data
>> transfer
>> takes place. A real good way to learn all this is with a packet sniffer.
>> Netmon is built into server editions of Windows but I like Ethereal a lot
>> better and it is free. The link below contains some basics on NBT. ---
>> Steve
>>
>> http://www.keyfocus.net/kfsensor/help/AdminGuide/adm_NB...
>> http://support.microsoft.com/default.aspx?scid=kb;en-us;832017 --- ports
>> used by Windows.
>>
>>
>> "/.dz" <dz@discussions.microsoft.com> wrote in message
>> news:64CF1392-1184-4248-AA5E-05C0EBD35316@microsoft.com...
>> > Steve:
>> > I did not lose interest -- but I did have other things to attend to.
>> > This
>> > particular thread has become almost a hobby with me -- so you are
>> > forewarned;
>> > I will probably keep going until you tire of my questions; and of
>> > course,
>> > I
>> > appreciate all the information you've already provided regardless of
>> > whether
>> > you continue or not.
>> >
>> > But if you elected to continue ...
>> >
>> > When I read the last response, this is what I 'hear', right or wrong.
>> > UDP
>> > 137 is used by the client to contact a WINS server for name resolution.
>> > UDP
>> > 138 I don't understand, unless it's a port simply to listen for
>> > responses
>> > to
>> > requests issued via UDP 137 and/or broadcasts. TCP 139 I think I
>> > understand
>> > -- using NETSTAT I can 'see' a couple of workstations have ESTABLISHED
>> > connections to TCP 139 on my server and recognize the 'foreign' IP
>> > address
>> > as
>> > valid users of the system.
>> >
>> > [By the way, if you happen to know of a relatively concise article that
>> > describes the NetBIOS protocol, perhaps replete with dialog examples,
>> > I'd
>> > be
>> > interested ....]
>> >
>> > ./dz
>> >
>> >
>> > "Steven L Umbach" wrote:
>> >
>> >> First off disabling netbios over tcp/ip will not stop null sessions
>> >> but
>> >> it
>> >> may reduce them. Netbios over tcp/ip is legacy [W98/NT4.0, etc] file
>> >> and
>> >> print sharing that uses ports 137UDP/138UDP/139TCP for netbios naming,
>> >> transport, and session services. It will use broadcasts only, if a
>> >> wins
>> >> server is not available. NBT [net bios over tcp/ip] uses port 137 UDP
>> >> for
>> >> naming for client to contact wins server, 138 UDP for browse list
>> >> maintenance, and 139 TCP for actual file sharing. Legacy clients can
>> >> only
>> >> use NBT and if disabled will not be able to do any name resolution,
>> >> browsing, or file sharing.
>> >>
>> >> Windows 2000/XP/2003 can use either NBT or CIFS [port 445TCP] and also
>> >> DNS
>> >> for name resolution of course. If NBT is disabled then Windows
>> >> 2000/XP/2003
>> >> will use DNS and port 445TCP for file and print sharing. A Windows
>> >> 2000/XP
>> >> Pro/2003 domain computer will always use dns name resolution first for
>> >> any
>> >> name resolution request. It will append parent domain suffix [or
>> >> whatever
>> >> you configure] to a non FQDN request. Windows 2000/XP/2003 in a
>> >> workgroup
>> >> however will use NBT first for name resolution for a non FQDN if it is
>> >> enabled.
>> >>
>> >> Care should be taken before disabling NBT to make sure no computers or
>> >> applications need to use it to refer to computers by name. If it is
>> >> disabled
>> >> then for 2000/XP/2003 you can still use names to refer to file shares.
>> >> DNS
>> >> FQDN will work and "flat" computer names may work if your dns can
>> >> resolve
>> >> the names by appending suffixes for domain computers. For non domain
>> >> computers you are best using only FQDN when referring to computer
>> >> names
>> >> if
>> >> NBT is disabled. While NBT is legacy technology it still is widely
>> >> used
>> >> in
>> >> most of today's networks and still is required in some cases such as
>> >> for
>> >> certain configurations with Exchange and clusters I believe. ---
>> >> Steve
>> >>
>> >>
>> >> "/.dz" <dz@discussions.microsoft.com> wrote in message
>> >> news:1AC558F8-332E-4CEB-BEC5-2564EB1FFB00@microsoft.com...
>> >> > Steve:
>> >> > As before, thank you for the explanation of the relationship between
>> >> > the
>> >> > 'null sessions' and the Computer Browser service -- one less source
>> >> > of
>> >> > ambiguity for me to deal with. Unfortunately, for reasons related
>> >> > to
>> >> > 'job
>> >> > security', I am not able to investigate the 'restrict anonymous
>> >> > access'
>> >> > option at this time. However, if at some point in the near future I
>> >> > am
>> >> > able
>> >> > to, I will add my experience to this dialog.
>> >> >
>> >> > That having been said, and if you are still willing, I'd like to
>> >> > return
>> >> > to
>> >> > the original response you provided and ask in detail about one of
>> >> > the
>> >> > other
>> >> > points -- disabling NETBIOS over tcp/ip. I'm fairly certain that I
>> >> > understand the premise of 'name resolution' and you've indicated
>> >> > that
>> >> > as
>> >> > long
>> >> > as the file-share users reference the share with either a FQDN (or
>> >> > equivalently, the workstation TCP/IP Advanced Properties DNS
>> >> > settings
>> >> > has
>> >> > an
>> >> > appropriate suffix in the list that results in a FQDN), name
>> >> > resolution
>> >> > should proceed OK. Question: Does this imply that NETBIOS - from
>> >> > the
>> >> > standpoint of file sharing - is only needed for name resolution?
>> >> > There's
>> >> > no
>> >> > other aspect to file sharing that is dependent upon NETBIOS?
>> >> > ./dz
>> >> >
>> >> > "Steven L Umbach" wrote:
>> >> >
>> >> >> The browser service is just one and the most common use of null
>> >> >> sessions.
>> >> >> However disabling the browser service simply prevents the computer
>> >> >> from
>> >> >> becoming a master browser or backup browser. If you can change the
>> >> >> security
>> >> >> option for additional restrictions for anonymous access to be no
>> >> >> access
>> >> >> without explicit anonymous permissions you will prevent null
>> >> >> connections
>> >> >> though apparently you may still see anonymous logon events in the
>> >> >> security
>> >> >> log as I experienced. The KB article below explains more on how to
>> >> >> do
>> >> >> this
>> >> >> but be sure to read the consequences first. --- Steve
>> >> >>
>> >> >> http://support.microsoft.com/?kbid=246261
>> >> >>
>> >> >> The following tasks are restricted when the RestrictAnonymous
>> >> >> registry
>> >> >> value
>> >> >> is set to 2 on a Windows 2000-based domain controller: . Down-level
>> >> >> member
>> >> >> workstations or servers are not able to set up a netlogon secure
>> >> >> channel.
>> >> >> . Down-level domain controllers in trusting domains are not
>> >> >> be
>> >> >> able
>> >> >> to
>> >> >> set up a netlogon secure channel.
>> >> >> . Microsoft Windows NT users are not able to change their
>> >> >> passwords
>> >> >> after they expire. Also, Macintosh users are not able to change
>> >> >> their
>> >> >> passwords at all.
>> >> >> . The Browser service is not able to retrieve domain lists or
>> >> >> server
>> >> >> lists from backup browsers, master browsers or domain master
>> >> >> browsers
>> >> >> that
>> >> >> are running on computers with the RestrictAnonymous registry value
>> >> >> set
>> >> >> to
>> >> >> 2.
>> >> >> Because of this, any program that relies on the Browser service
>> >> >> does
>> >> >> not
>> >> >> function properly
>> >> >>
>> >> >>
>> >> >> "/.dz" <dz@discussions.microsoft.com> wrote in message
>> >> >> news:6D02852B-4580-422D-A4F1-81D7CC52C8FA@microsoft.com...
>> >> >> > Again, thanks. Here's what I know now that I didn't prior to
>> >> >> > your
>> >> >> > response --
>> >> >> > Your version of the 'null session' command has two less ""s in
>> >> >> > it.
>> >> >> > And
>> >> >> > that
>> >> >> > makes it work! So now I can indeed verify that I am able to
>> >> >> > establish
>> >> >> > a
>> >> >> > null
>> >> >> > session with my server; and 'yes' it apparently does log a 538
>> >> >> > upon
>> >> >> > session
>> >> >> > termination. But allow me a further quesiton: Since I have the
>> >> >> > 'Computer
>> >> >> > Browser' service disabled on the server, why are 'null sessions'
>> >> >> > still
>> >> >> > allowed? I was under the impression that null sessions only
>> >> >> > existed
>> >> >> > to
>> >> >> > facilitate the 'enumeration' of resouces that the browsing
>> >> >> > capability
>> >> >> > supports; and therefore by disabling the Computer Browser service
>> >> >> > I
>> >> >> > would
>> >> >> > effectively prevent 'null sessions' from occurring. ??
>> >> >> >
>> >> >> > "Steven L Umbach" wrote:
>> >> >> >
>> >> >> >> I am experiencing something different than you are [ as shown
>> >> >> >> below].
>> >> >> >> As
>> >> >> >> long as the security option for additional restrictions for
>> >> >> >> anonymous
>> >> >> >> access
>> >> >> >> is NOT set to no access without explicit anonymous permissions I
>> >> >> >> am
>> >> >> >> able
>> >> >> >> to
>> >> >> >> create a null session. When I do have no access without explicit
>> >> >> >> anonymous
>> >> >> >> permissions enabled I can not create a null session and I simply
>> >> >> >> get a
>> >> >> >> system error 5 has occurred - access is denied. Even when access
>> >> >> >> was
>> >> >> >> denied
>> >> >> >> to my null session an Event ID 538 is recorded in the security
>> >> >> >> log
>> >> >> >> of
>> >> >> >> my
>> >> >> >> server for successful anonymous logoff which indicates that
>> >> >> >> these
>> >> >> >> events
>> >> >> >> may
>> >> >> >> be recorded even if a null session is denied. You might want to
>> >> >> >> see
>> >> >> >> if
>> >> >> >> you
>> >> >> >> have any current sessons to your server before you try null
>> >> >> >> session
>> >> >> >> with
>> >> >> >> "
>> >> >> >> net use " command and delete them if there are any and try
>> >> >> >> again. I
>> >> >> >> doubt
>> >> >> >> Client for Microsoft Networks enabled on your server is causing
>> >> >> >> the
>> >> >> >> null
>> >> >> >> sessions to be created to your server. If your server does not
>> >> >> >> need
>> >> >> >> to
>> >> >> >> logon
>> >> >> >> to a domain or access shares/resources on other computers then
>> >> >> >> you
>> >> >> >> should
>> >> >> >> be
>> >> >> >> able to diable it with no ill effect. A dedicated web server for
>> >> >> >> instance
>> >> >> >> would not need to use Client for Microsoft Networks. --- Steve
>> >> >> >>
>> >> >> >> D:\Documents and Settings\Steve>net use \\192.168.1.105\ipc$ ""
>> >> >> >> /u:""
>> >> >> >> The command completed successfully.
>> >> >> >>
>> >> >> >>
>> >> >> >> D:\Documents and Settings\Steve>net use \\192.168.1.105\ipc$ ""
>> >> >> >> /u:""
>> >> >> >> System error 5 has occurred.
>> >> >> >>
>> >> >> >> Access is denied.
>> >> >> >>
>> >> >> >> Event Type: Success Audit
>> >> >> >> Event Source: Security
>> >> >> >> Event Category: Logon/Logoff
>> >> >> >> Event ID: 538
>> >> >> >> Date: 3/16/2005
>> >> >> >> Time: 11:56:16 PM
>> >> >> >> User: NT AUTHORITY\ANONYMOUS LOGON
>> >> >> >> Computer: SERVER1-2000
>> >> >> >> Description:
>> >> >> >> User Logoff:
>> >> >> >> User Name: ANONYMOUS LOGON
>> >> >> >> Domain: NT AUTHORITY
>> >> >> >> Logon ID: (0x0,0x2CFBA3)
>> >> >> >> Logon Type: 3
>> >> >> >>
>> >> >> >>
>> >> >> >> "/.dz" <dz@discussions.microsoft.com> wrote in message
>> >> >> >> news:1D63D35D-431D-4A78-83BD-AE4A2E8EE0D1@microsoft.com...
>> >> >> >> > Steve:
>> >> >> >> > First thanks very much for the response. I've noticed that
>> >> >> >> > your
>> >> >> >> > name
>> >> >> >> > is
>> >> >> >> > on
>> >> >> >> > a lot of the responses in this forum and I appreciate the help
>> >> >> >> > as
>> >> >> >> > much
>> >> >> >> > as
>> >> >> >> > I'm
>> >> >> >> > sure the other people do as well.
>> >> >> >> >
>> >> >> >> > So anytime you get tired of this thread, it will probably
>> >> >> >> > die --
>> >> >> >> > but
>> >> >> >> > I
>> >> >> >> > will
>> >> >> >> > continue to ask questions as long as you continue to respond.
>> >> >> >> >
>> >> >> >> > In your response, you mentioned 'null sessions'. In other
>> >> >> >> > articles
>> >> >> >> > I've
>> >> >> >> > read, there is a reference to using the statement [net use
>> >> >> >> > \\servername\ipc$
>> >> >> >> > """" /u:""] to check if null sessions are able to be created.
>> >> >> >> > When
>> >> >> >> > I
>> >> >> >> > attempted this statement from my workstation, targetting the
>> >> >> >> > 'servername'
>> >> >> >> > being discussed in this posting, I received the "Logon
>> >> >> >> > failure:
>> >> >> >> > unknown
>> >> >> >> > user
>> >> >> >> > name or bad password" message at the workstation, and the
>> >> >> >> > server
>> >> >> >> > logged
>> >> >> >> > an
>> >> >> >> > event 529 Logon failure, explicitly indicating my userid,
>> >> >> >> > workstation,
>> >> >> >> > and
>> >> >> >> > domain. From this info, I'm assuming that the 'null sessions'
>> >> >> >> > discussion
>> >> >> >> > does not apply to my situation. Is that a valid conclusion?
>> >> >> >> > Also,
>> >> >> >> > the
>> >> >> >> > Computer Browser service is disabled (and has been since
>> >> >> >> > installation)
>> >> >> >> > on
>> >> >> >> > the
>> >> >> >> > server. Am I also 'on-track' here in that these two items are
>> >> >> >> > directly
>> >> >> >> > related? (That is, 'null sessions' are enabled - i.e.,
>> >> >> >> > required -
>> >> >> >> > for
>> >> >> >> > the
>> >> >> >> > Computer Browser service to function)
>> >> >> >> >
>> >> >> >> > I want to ask about the other items in your response as well,
>> >> >> >> > but
>> >> >> >> > to
>> >> >> >> > keep
>> >> >> >> > the dialog within reasonable bounds, I'm electing to go
>> >> >> >> > through
>> >> >> >> > it
>> >> >> >> > one
>> >> >> >> > item
>> >> >> >> > at a time --- starting (I think) with the most clearcut.
>> >> >> >> >
>> >> >> >> > Also in this thread, I need to about the 'Client for Microsoft
>> >> >> >> > Networks' .
>> >> >> >> > The server has this protocol enabled. Two further questions:
>> >> >> >> > a)
>> >> >> >> > This
>> >> >> >> > client
>> >> >> >> > is only necessary if the computer (the server in this case)
>> >> >> >> > wants
>> >> >> >> > to
>> >> >> >> > access
>> >> >> >> > other NETBIOS resources on the net; it is not required for
>> >> >> >> > other
>> >> >> >> > computers
>> >> >> >> > on
>> >> >> >> > the net to reach its (the server's) resources. Is this
>> >> >> >> > correct?
>> >> >> >> > b)
>> >> >> >> > the
>> >> >> >> > 'Client for Microsoft Networks' is not responsible for the 538
>> >> >> >> > logout
>> >> >> >> > events
>> >> >> >> > mentioned in the original post?
>> >> >> >> >
>> >> >> >> > Any further dialog is greatly appreciated.
>> >> >> >> > ./dz
>> >> >> >> >
>> >> >> >> > "Steven L Umbach" wrote:
>> >> >> >> >
>> >> >> >> >> It is common to see those Events on computers using Windows
>> >> >> >> >> networking
>> >> >> >> >> and
>> >> >> >> >> that have file and print sharing and Client for Microsoft
>> >> >> >> >> networks
>> >> >> >> >> enabled.
>> >> >> >> >> Those often are null sessions used by the computer browser
>> >> >> >> >> service.
>> >> >> >> >> While
>> >> >> >> >> null sessions can be used to enumerate users, groups, and
>> >> >> >> >> shares
>> >> >> >> >> you
>> >> >> >> >> can
>> >> >> >> >> mitigate the risk by using a firewall to prevent internet
>> >> >> >> >> access
>> >> >> >> >> to
>> >> >> >> >> null
>> >> >> >> >> sessions, enforcing strong passwords on your network, and
>> >> >> >> >> making
>> >> >> >> >> sure
>> >> >> >> >> your
>> >> >> >> >> share/folder permissions only allow authorized users access.
>> >> >> >> >>
>> >> >> >> >> There are things you can do to reduce there occurrence as
>> >> >> >> >> ling
>> >> >> >> >> as
>> >> >> >> >> the
>> >> >> >> >> changes do not interfere with your network access for users.
>> >> >> >> >> For
>> >> >> >> >> instance
>> >> >> >> >> disabling netbios over tcp/ip, disabling the computer browser
>> >> >> >> >> service,
>> >> >> >> >> and
>> >> >> >> >> configuring the security option for "additional restrictions
>> >> >> >> >> for
>> >> >> >> >> anonymous
>> >> >> >> >> access" to be " no access without explicit anonymous
>> >> >> >> >> permissions".
>> >> >> >> >> If
>> >> >> >> >> you
>> >> >> >> >> disable netbios over tcp/ip on a computer it will no longer
>> >> >> >> >> show
>> >> >> >> >> in
>> >> >> >> >> or
>> >> >> >> >> be
>> >> >> >> >> able to use My Network Places but access to shares can still
>> >> >> >> >> be
>> >> >> >> >> done
>> >> >> >> >> via
>> >> >> >> >> fully qualified domain name or possibly even netbios name as
>> >> >> >> >> long
>> >> >> >> >> as
>> >> >> >> >> dns
>> >> >> >> >> can
>> >> >> >> >> resolve the non FQDN by appending parent suffix to the
>> >> >> >> >> request.
>> >> >> >> >> The
>> >> >> >> >> link
>> >> >> >> >> below explains anonymous access more and the security option
>> >> >> >> >> to
>> >> >> >> >> restrict
>> >> >> >> >> it
>> >> >> >> >> along with possible consequences of doing such. --- Steve
>> >> >> >> >>
>> >> >> >> >> http://support.microsoft.com/?kbid=246261
>> >> >> >> >>
>> >> >> >> >> "/.dz" </.dz@discussions.microsoft.com> wrote in message
>> >> >> >> >> news:480AE832-9FE3-4740-A265-6F6CA5A898FD@microsoft.com...
>> >> >> >> >> > The security event log on our W2K, SP4 server has hundreds
>> >> >> >> >> > of
>> >> >> >> >> > the
>> >> >> >> >> > above
>> >> >> >> >> > messages in it. There are no associated 'logon' events,
>> >> >> >> >> > just
>> >> >> >> >> > the
>> >> >> >> >> > 'logoff'
>> >> >> >> >> > events.
>> >> >> >> >> >
>> >> >> >> >> > File and Print sharing is enabled on this server.
>> >> >> >> >> >
>> >> >> >> >> > There are several published file shares (all hidden); and
>> >> >> >> >> > there
>> >> >> >> >> > are
>> >> >> >> >> > individuals who are authorized to use those shares. The
>> >> >> >> >> > security
>> >> >> >> >> > log
>> >> >> >> >> > does
>> >> >> >> >> > contain 540/538 'pairs' that reflect the credentials of
>> >> >> >> >> > these
>> >> >> >> >> > known
>> >> >> >> >> > users
>> >> >> >> >> > (user/domain). (These are also 'Logon Type 3') But the
>> >> >> >> >> > number
>> >> >> >> >> > of
>> >> >> >> >> > 538
>> >> >> >> >> > NT
>> >> >> >> >> > AUTHORITY/ANONYMOUS LOGON events absolutely dwarfs the
>> >> >> >> >> > number
>> >> >> >> >> > of
>> >> >> >> >> > "known
>> >> >> >> >> > user"
>> >> >> >> >> > logon/logoff events.
>> >> >> >> >> >
>> >> >> >> >> > The server itself is not a domain controller. It was until
>> >> >> >> >> > recently
>> >> >> >> >> > a
>> >> >> >> >> > member of a NT domain, and now is under AD (I don't know
>> >> >> >> >> > how
>> >> >> >> >> > to
>> >> >> >> >> > state
>> >> >> >> >> > that
>> >> >> >> >> > with any accuracy). 'Known user' logon/logoff events are
>> >> >> >> >> > present
>> >> >> >> >> > for
>> >> >> >> >> > both
>> >> >> >> >> > the 'older' NT domain, and the newer 'AD' whatever).
>> >> >> >> >> >
>> >> >> >> >> > I've scoured newsgroups and the MS web site without any
>> >> >> >> >> > luck
>> >> >> >> >> > whatsoever.
>> >> >> >> >> > Any feedback would be greatly appreciated.
>> >> >> >> >> >
>> >> >> >> >>
>> >> >> >> >>
>> >> >> >> >>
>> >> >> >>
>> >> >> >>
>> >> >> >>
>> >> >>
>> >> >>
>> >> >>
>> >>
>> >>
>> >>
>>
>>
>>
!