TCP/IP doubles 0XFF characters in data stream

[Guest]

Archived from groups: microsoft.public.platformsdk.networking,microsoft.public.win32.programmer.networks,microsoft.public.windowsnt.protocol.tcpip (More info?)

My application sends data from one host to another via TCP/IP. Somehow,
whenever the remote host sends a 0XFF character, two 0XFF characters are
received at the local host. Is there any TCP/IP setting that could cause
this? The OS on the remote host is Redhat Linux 7.1 and, on the local host,
Windows XP. On the XP host, Winsock v2.x is in use.

A further consideration is that the ZMODEM file transfer protocol is the
protocol being used for the data transfer, running over TCP/IP. I can't see
anything in the ZMODEM spec. about 0XFF being escaped with two 0XFF
characters. Have I missed something?

Many thanks.

 

[Guest]

Archived from groups: microsoft.public.platformsdk.networking,microsoft.public.win32.programmer.networks,microsoft.public.windowsnt.protocol.tcpip (More info?)

In article <O49NINWkEHA.1028@TK2MSFTNGP12.phx.gbl>,
Andrew Chalk <achalk@XXXmagnacartasoftware.com> wrote:
>My application sends data from one host to another via TCP/IP. Somehow,
>whenever the remote host sends a 0XFF character, two 0XFF characters are
>received at the local host. Is there any TCP/IP setting that could cause
>this? The OS on the remote host is Redhat Linux 7.1 and, on the local host,
>Windows XP. On the XP host, Winsock v2.x is in use.
>
>A further consideration is that the ZMODEM file transfer protocol is the
>protocol being used for the data transfer, running over TCP/IP. I can't see
>anything in the ZMODEM spec. about 0XFF being escaped with two 0XFF
>characters. Have I missed something?
>
>Many thanks.

It sounds like your data is being sent over a "Telnet" connection. Raw
TCP/IP will pass your 0xff bytes as single 0xff bytes. On Telnet, the
0xff byte is used as a control character, so each 0xff of data will be sent
as 2 0xff's to distinguish between data bytes and control bytes.

Maybe you're using some kind of telnet library on your Windows machine?

Patrick
========= For LAN/WAN Protocol Analysis, check out PacketView Pro! =========
Patrick Klos Email: patrick@klos.com
Klos Technologies, Inc. Web: http://www.klos.com/
==================== What goes around, comes around... =====================

 

[Guest]

Archived from groups: microsoft.public.platformsdk.networking,microsoft.public.win32.programmer.networks,microsoft.public.windowsnt.protocol.tcpip (More info?)

Correct. Someone in another newsgroup pointed this out to me. Many thanks
for your help.

- Andrew
<patrick@klos.com> wrote in message news:ch9tep$lre$1@pyrite.mv.net...
> In article <O49NINWkEHA.1028@TK2MSFTNGP12.phx.gbl>,
> Andrew Chalk <achalk@XXXmagnacartasoftware.com> wrote:
>>My application sends data from one host to another via TCP/IP. Somehow,
>>whenever the remote host sends a 0XFF character, two 0XFF characters are
>>received at the local host. Is there any TCP/IP setting that could cause
>>this? The OS on the remote host is Redhat Linux 7.1 and, on the local
>>host,
>>Windows XP. On the XP host, Winsock v2.x is in use.
>>
>>A further consideration is that the ZMODEM file transfer protocol is the
>>protocol being used for the data transfer, running over TCP/IP. I can't
>>see
>>anything in the ZMODEM spec. about 0XFF being escaped with two 0XFF
>>characters. Have I missed something?
>>
>>Many thanks.
>
> It sounds like your data is being sent over a "Telnet" connection. Raw
> TCP/IP will pass your 0xff bytes as single 0xff bytes. On Telnet, the
> 0xff byte is used as a control character, so each 0xff of data will be
> sent
> as 2 0xff's to distinguish between data bytes and control bytes.
>
> Maybe you're using some kind of telnet library on your Windows machine?
>
> Patrick
> ========= For LAN/WAN Protocol Analysis, check out PacketView Pro!
> =========
> Patrick Klos Email: patrick@klos.com
> Klos Technologies, Inc. Web: http://www.klos.com/
> ==================== What goes around, comes around...
> =====================

 

[Guest]

Archived from groups: microsoft.public.platformsdk.networking,microsoft.public.win32.programmer.networks,microsoft.public.windowsnt.protocol.tcpip (More info?)

> ... whenever the remote host sends a 0XFF character, two 0XFF characters
> are received at the local host ...

> ... Is there any TCP/IP setting that could cause this? ...

no

> ... the ZMODEM file transfer protocol is the protocol being used ...

wild guess ... the zmodem protocol is not being implemented properly on one
end (or the other end, or both)

try using a modem program that has zmodem (eg I think hyperterminal on
windwos does), at either end to see which of your implementations of zmodem
is screwed

--
Louis Solomon
www.steelbytes.com