If you are trying to set up a PPTP VPN access and cannot connect to it using a Windows "dial up" or Windows VPN client. Usually, users will get an error message when using the built-in Windows VPN support: "Error 800: Unable to establish the VPN connection".

Either way, if you have a Cisco PIX 515 or Cisco PIX 515E and are having problems with PPTP VPNs (publishing and using) just run this through the command line and the firewall will allow PPTP traffic to flow through:

fixup protocol pptp 1723

Tags: cisco, cisco pix 515, error 800 unable to establish the vpn connection, error message, firewall, pix 515, pix 515e, pptp vpn, protocol, traffic, vpns, windows vpn client