Sign in with
Sign up | Sign in
Your question

VPN over GPRS not working?

Last response: in Networking
Share
Anonymous
September 29, 2005 7:31:25 AM

Archived from groups: comp.dcom.vpn (More info?)

I'm trying to establish a VPN tunnel from my laptop over GPRS to my office
LAN. VPN works fine from broadband or dialup, but GPRS fails.

Client is Windows XP, Server is pptpd/pppd on a Snapgear appliance, mobile
provider is O2 Germany.
It seems the GPRS connection works via NAT and that this may be the cause
of the problem. The log shows "LCP: timeout sending Config-Requests" which
might also indicate that my side couldn't answer because of NAT.

Is there anything I can do about that concerning the server configuration?
I do have good knowledge about Linux and partly about networking but
exactly none about pptpd/pppd, I just use the web interface provided by
the router. I can edit configuration files (pptpd.conf and options.pptp as
I understand) directly if necessary.

Other possible causes might be MTU or the GPRS gateway not allowing highly
encrypted authentication. I tried everything down to even no
authentication, nothing worked over GPRS. MTU seems to be at normal 1500.
So, I think both are not relevant here.

Kai

More about : vpn gprs working

Anonymous
September 29, 2005 11:29:00 PM

Archived from groups: comp.dcom.vpn (More info?)

Kai Schaetzl wrote:
> I'm trying to establish a VPN tunnel from my laptop over GPRS to my office
> LAN. VPN works fine from broadband or dialup, but GPRS fails.
>
> Client is Windows XP, Server is pptpd/pppd on a Snapgear appliance, mobile
> provider is O2 Germany.
> It seems the GPRS connection works via NAT and that this may be the cause
> of the problem. The log shows "LCP: timeout sending Config-Requests" which
> might also indicate that my side couldn't answer because of NAT.
>
> Is there anything I can do about that concerning the server configuration?
> I do have good knowledge about Linux and partly about networking but
> exactly none about pptpd/pppd, I just use the web interface provided by
> the router. I can edit configuration files (pptpd.conf and options.pptp as
> I understand) directly if necessary.
>
> Other possible causes might be MTU or the GPRS gateway not allowing highly
> encrypted authentication. I tried everything down to even no
> authentication, nothing worked over GPRS. MTU seems to be at normal 1500.
> So, I think both are not relevant here.
>
> Kai
>

Nothing you can do but complain to the GPRS service provider.



--
WARNING! Email address has been altered for spam resistance.
Please remove the -deletethispart-. section before replying directly.
Mike Drechsler (mike-newsgroup@-deletethispart-.upcraft.com)
Anonymous
September 30, 2005 3:31:18 AM

Archived from groups: comp.dcom.vpn (More info?)

Mike Drechsler - SPAM PROTECTED EMAIL schrieb am Thu, 29 Sep 2005 19:29:00
GMT:

> Nothing you can do but complain to the GPRS service provider.

Figured that, thanks!

Kai
Related resources
December 22, 2005 3:01:10 PM

set your mtu down to 1300 and try the connection again.

I would think your mtu size is the most likely cause of your connection issues.
January 14, 2006 10:52:02 AM

hmmm, VPN sucks alot of bandwidth, when it needs encryption (full tunneling) and GPRS uses packet-switching, thats 160 kbits maximum, i would be surprised if it works in anyway?
September 13, 2007 2:35:12 AM

My 2 cents worth: (regarding IPSec VPN)

From my experience, most GPRS connections will give a PRIVATE ip address. This means that we are connected to an internal network which uses a gateway to access the real Internet. Most gateways "break" the IPSec protocol (unless the gateway is setup to allow IPSec passthru).

I have noticed that some GPRS provider have packages that provide a Public IP address (I *** that these will be directly connected to the Internet). These packages (e.g. from cingular of US) MIGHT support IPSec VPN
September 13, 2007 2:37:40 AM

P.S.
I have managed to get VPN working via GSM (by dial-up into a normal ISP) which then gives me a Public IP. BUT this GSM connection is 9.6kbps - which is OK only for light messaging services.
!