PPTP on Cisco ASA or PIX 6.3 or later code

In PIX 6.3 and later, support for PPTP through the PIX has been added.

Before version 6.3, a PIX needed to be configured to allow the GRE tunnel back from a PPTP server.

As of version 6.3, the firewall merely needs:

fixup protocol pptp 1723

Prior to 6.3, the following was needed:

static (inside,outside) outside_ip inside_ip netmask 255.255.255.255

access-group pptp-acl in interface outside

The Cisco document: http://www.cisco.com/warp/public/110/pix_pptp.html