I am having a problem with a VPN implementation. I am using PPTP, not IPsec. I have two sites, one has a Pix 506 and the other has a Pix 501. Both firewall configurations are configured the same. If a remote user connects using any standard Microsoft VPN client, they are able to connect very easily with no problems. However, any Microsoft VPN client that tried to attach from behind a Cisco firewall will not work. The connection hangs up at "Verifiying User name and Password" and then gives a that the remote server doesnt pick up. I have had an external company trying to access my networks but they get the same message. They connect to many other PIX firewalls so I know the issue must be with my setup. I am able to reproduce this issue when I try to communicate between sites. Any help would be greatly appreciated!
Actually you need to make sure that the device that is doing PAT (a FW) that your PPTP users are sitting behind, is PPTP aware PAT e,g, a Cisco router having 12.1(2)T or later support PPTP PassThru feature.
You can try putting a static translation entry for a particular host on the FW (doing PAT) or connect via dial-up account to double check thats what is happening because of PAT.