How to pass PPTP traffic through a PIX Firewall

Cisco PIX Firewalls require two elements to pass traffic from outside (higher security) to inside (lower security): a static translation and a conduit.

For this example, assume a server has IP address and there is an available outside address of

First, create the static translation. This configuration line establishes a relationship between (public Internet IP address) and (inside, private IP address).

fixup protocol pptp 1723
static (inside,outside) netmask 0 0

Next, create appropriate conduits to allow specific traffic to pass from the outside to the Inside interface. PPTP uses TCP/1723, and IP/47 GRE.

conduit permit tcp eq 1723 any
conduit permit gre host anyor
access-list 101 permit tcp any host 1723
access-list 101 permit gre any host
access-group 101 in interface outside

A couple of notes:

In the conduits and access-lists, the any keyword allows matching traffic from any IP address to pass through the firewall. This should be replaced with the source IP address of the PPTP tunnel, if at all possible.

In the access-lists, verify any existing access-lists or other traffic needed before entering the last line!


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