Can't access VPN Server

[azriel550]

I have set up a windows xp machine as a vpn server. It is behind a NAT router and I have forwarded port 1723 to the local ip of the server.

I have no trouble connecting to the vpn server, but I cannot ping or access any of the resources on the vpn server using the local ip address of the server (192.168.1.1).

HOWEVER

I can access other resources on the network via the VPN without any issues.

What confuses me most about this is that I can access resources on the VPN server if I find the "Server IP Address" from the "Details" tab of the VPN connection status when connected. This address however is something like 192.168.1.106 and not the true local address 192.168.1.1 as written above.

Why can I only access the vpn server via this second address (which is not always the same)? Why can't I access the VPN server using the IP address I would use as if I were on site?

I have set up a VPN in this manner a number of times in the past and have yet to run in to this particular issue. Ive been googling it for a couple of days and can't find anything useful.

Any help would be greatly appreciated.

 

[GVN]

You may have "PPTP Filtering" enabled on that NIC, which specializes that NIC to handle PPTP traffic only. Check the Network settings and let us know....

GVN

 

[azriel550]

Thanks GVN for your post.

Just to clarify, there is only one NIC in this machine.

In the "Advanced" tab of the properties sheet of the NIC itself, there is no mention of PPTP filtering. The following parameters => values are present.

Adaptive Interrupt => Enabled
Connection Type => Auto Negotiation
Flow Control => Disabled
Network Address => Not Present
Receive Buffers => 64
Transmit Buffers => 64

Should I be looking somewhere else for this setting?

Thanks again for your post.

 

[smah]

Look in Network Connections, Properties, TCP/IP, Properties button, Advanced button, Options tab, Properties button

Steve

 

[azriel550]

Thanks to both of you for your help..

Steve - There was no mention of PPTP filtering there either. Thanks for your post though.

After many hours I think I may have finally solved the problem. I had to enable XP as a router by changing the registry key:

HKLM\SYSTEM\CURRENTCONTROLSET\SERVICES\TCPIP\PARAMETERS\IPENABLEROUTER

to 1

Then I rebooted the machine, and had to disable the windows firewall to get it to work - but it works finally.

As I said previously, I've set these up before and not needed to change anything in the registry. If anyone has a clue as to why this is the case, I'd love to know.

Thanks again for your posts.