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eibgrad

join:2010-03-15
reply to FlameN

Re: How to forward gre - VPN server behind windows server 2003

GRE is not a port. It’s not something you can forward. It's a TCP protocol (specifically, #47) and it either is or isn't implemented by your router. And if the router supports VPN pass-through, it probably does.


FlameN

@inholland.nl
I understand it's not a port. But currently windows server 2003 is acting as a router and it forwards the TCP port 1723 packets to the VPN server but the GRE packets do not reach the VPN server.

bdnhsv

join:2012-01-20
Huntsville, AL
Let's back up and make sure we all know which type of tunnel you're wanting to create. PPTP, L2TP, IPsec, OpenVPN, etc.


FlameN

@chello.nl
Ya, I forgot to mention. I'm using PPTP.

bdnhsv

join:2012-01-20
Huntsville, AL
OK - what's between 16.1 and 1.1 ? What are the ISP's on each side and what types of services are they, modems involved, routers, etc. ?


FlameN

@chello.nl
16.1 and 1.1 are both on a Windows server 2003 machine and there are no ISPs. I'm testing in LAN environment. the Windows server 2003 is running a proxy to regulate the internal traffic and also has a mapped link for the TCP port 1723 to the VPN server.

bdnhsv

join:2012-01-20
Huntsville, AL
Doesn't win2k3 have a built in firewall? Try turning it off and see if your GRE traffic makes it to the other side.


FlameN

@chello.nl
Firewall is off with no filters. I'm 99% sure. Gonna check tomorrow morning.

bdnhsv

join:2012-01-20
Huntsville, AL
If that doesn't work - have you tried connecting your vpn client directly to the vpn server for a sanity check?


FlameN

@inholland.nl
Just tested it. VPN functions normaly when connecting from External client to Windows Server and Windows server to Internal VPN server. all firewalls are off.


FlameN

@inholland.nl
reply to bdnhsv
A bit of an update. The packets not getting to the Internal VPN server are displayed in wireshark as protocol: "ppp lcp" with info: configuration request