Advice needed on how to investigate a VPN/Firewall problem
Posted on 2004-04-25
The original setup:
2 Windows XP PC's connected via 100Mbit network switch.
Broadband internet connection provided by a router.
The PC's each have standard 100Mbit network cards, TCP/IP and default gateway/IP Address/DNS information loaded from the router via DHCP.
Can ping each PC and Router from eachother without any problems (all on 192.168 network)
The change to one of the PCs:
Installed AT&T Global Network Client and Firewall configured for VPN access over my existing Internet connection.
Configured the AT&T Firewall software to be enabled only on the Wan Miniport (i.e., the VPN) connection and NOT the local network card.
The problem following the change:
Everything works find when the VPN connection is not connected.
Upon connection, the PC that is connected can no longer ping the other PC and vice versa.
The VPN connection itself works fine and I can ping other remote systems on the connected network.
Once VPN is disconnected, I can ping to/from the PC as normal again.
ipconfig when connected via VPN:
The local network card shows its DHCP allocated 192.168.x.x IP address (from the router) and the router as the default gateway, i.e., no change to when not connected.
The Wan Miniport connection shows its DHCP allocated 192.168.x.x IP address (from AT&T) not conflicting with any local addresses and a blank default gateway.
Can anyone suggest how I can continue to use my local network whilst connected over VPN to a remote network?
If not, can anyone suggest what steps I can take to find out where/how the pings are getting blocked when connected, i.e., how far does the traffic get, what are the responses? Is there any network diagnostic software (preferably freeware) that is recommended for resolving this type of issue.
Any help would be much appreciated.