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FlameN
@inholland.nl

FlameN

Anon

How to forward gre - VPN server behind windows server 2003

Hi everyone,

I'm new here and I need some help setting up a vpn server.

Basically I need a way to forward gre packets from an external network to the internal network using Windows Server 2003.

In more detail I have this scenario:
(vpn client).16.2-external-.16.1(win server 2003).1.1-internal-.1.2(vpn server)

The idea is for the vpn client to connect to the server through the windows server using the external ip(192.168.16.1) of the server.
I have forwarded tcp port 1723 and that part works okay. But I need a way to forward the gre packets to the vpn server.

Does any know some way or software that can do this in windows server 2003?
Any help is appreciated.

eibgrad
join:2010-03-15
united state

eibgrad

Member

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

FlameN

Anon

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

bdnhsv

Member

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

FlameN

Anon

Ya, I forgot to mention. I'm using PPTP.

bdnhsv
join:2012-01-20
Huntsville, AL

bdnhsv

Member

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

FlameN

Anon

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

bdnhsv

Member

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

FlameN

Anon

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

bdnhsv
join:2012-01-20
Huntsville, AL

bdnhsv

Member

If that doesn't work - have you tried connecting your vpn client directly to the vpn server for a sanity check?

FlameN
@inholland.nl

FlameN

Anon

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

FlameN to bdnhsv

Anon

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
HELLFIRE
MVM
join:2009-11-25

HELLFIRE to FlameN

MVM

to FlameN
said by eibgrad:

It's a TCP protocol

Me being nitpicky, but it's actually IP protocol #47....

FlameN can you do a better diagram of what your setup is, I'm having a very hard time visualizing it.

Regards
FlameN
join:2012-06-28

FlameN to FlameN

Member

to FlameN
I have 3 windows PCs with 2 different networks: internal and external. the Middle PC that connects to both networks and runs on windows server 2003 while the other 2 PCs each have 1 NIC and run win XP. It also use Proxy Plus to forward tcp traffic from the external interface to the VPN server on the internal network.
HELLFIRE
MVM
join:2009-11-25

HELLFIRE to FlameN

MVM

to FlameN
Can you actually DRAW this out FlameN, including all physical and logical connectivity? Even in MSPaint if you have to.

Regards