HELP ! Which ports does VPN use??

[jantie]

Hi all,

I have a problem. I have a network at the office, connected to the internet trough a permanent internet connection with a fixed ip address. We are running our own webserver and mailserver and that works fine.

I'm trying to set up a VPN. I use a Win2K Server and installed RAS. I configured all the settings and I can make a VPN connection using a computer that is inside my network.

When I try to make a vpn connection with a computer that is outside my network, behind the router, I get the error message that the remote computer isn't responding (while checking username and password).

I think the problem is the port mapping on the router. I use a Cisco805 router with NAT. I know how to map tcp/ip ports and I've mapped port 1723 to the VPN server. Is there another port that I have to map to use VPN??

Thanx alot,

Jan

 

[ManagerJay]

Have you also allowed protocol 47 (GRE)?



Jay

 

[jantie]

No, I haven't. Is mapping port 47 just the same as port 1723?? (tcp or udp?)

 

[horizonIT]

After you have set up port forwarding, allow ports 47, 1723, and 3004 through NAT on your router. This should allow VPN to do its thing.

Later,
HorizonIT

 

[John Lewis]

Did anyone happen to notice that this thread has been dead for 2 1/2 years?

One more time, just so someone doesn't pick this one up and make a bigger problem.

A pptp VPN requires that forwarding be configured on the SERVER side for tcp on port 1723 only.

PROTOCOL 47 (not port 47) needs to be allowed to pass through. This is sometimes referred to as passing GRE (Generic Routing Encapsulation protocol). This is most commonly listed as "PPTP passthrough". Often it is on by default and you have to do nothing.

On the client side, no specific forwarding should be required on a recent NAT firewall/router other than PPTP passthrough should be enabled. Some will have an option to track NAT'd outbound connections, but this is generally default and often not even presented as something that can be turned off. Older equipment may have a problem, often solved by updated firmware.

What in the world is 3004? Looks to be registered to CSoft. Probably not a security issue, but certainly not needed for pptp (or ipsec, l2tp).