Core issue
The PIX Firewall does not permit protocol-specific traffic, related to multimedia applications, to pass through it using Port Address Translation (PAT). Port mappings with PAT can confuse the PIX when it runs multimedia applications.
PAT does not work with most H.323 multimedia applications and caching name servers. Some multimedia applications can conflict with port mappings provided by PAT. PAT does not work with the established command.
PAT works with these:
- Remote-Procedure Call (RPC)
- The outbound traceroute command.
Resolution
To resolve this issue, refer to Configure and Troubleshoot the Cisco Secure PIX Firewall with a Single Internal Network.
Configuring Application Inspection (Fixup) categorizes a few applications and lists whether these applications work with NAT or PAT. Also, refer to the global command, which is used to configure PAT on PIX.
PIX Software Version
PIX version 4.x
PIX version 5.x
PIX version 6.x
PIX version 7.x
