Cisco 7604 Configuration Guide - Page 492
SIP Inspection, SIP Inspection Overview
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SIP Inspection Chapter 22 Applying Application Layer Protocol Inspection Example 22-11 Enabling and Configuring RTSP Inspection hostname(config)# access-list rtsp_acl permit tcp any any eq 554 hostname(config)# access-list rtsp_acl permit tcp any any eq 8554 hostname(config)# class-map rtsp-traffic hostname(config-cmap)# match access-list rtsp_acl hostname(config-cmap)# policy-map sample_policy hostname(config-pmap)# class rtsp_port hostname(config-pmap-c)# inspect rtsp hostname(config-pmap-c)# service-policy sample_policy interface outside SIP Inspection This section describes how to enable SIP application inspection and change the default port configuration. This section includes the following topics: • SIP Inspection Overview, page 22-76 • SIP Instant Messaging, page 22-77 • IP Address Privacy, page 22-78 • Configuring a SIP Inspection Policy Map for Additional Inspection Control, page 22-78 • Configuring SIP Timeout Values, page 22-82 • SIP Inspection Enhancement, page 22-82 • Verifying and Monitoring SIP Inspection, page 22-86 • SIP Sample Configuration, page 22-87 SIP Inspection Overview SIP, as defined by the IETF, enables call handling sessions, particularly two-party audio conferences, or "calls." SIP works with SDP for call signalling. SDP specifies the ports for the media stream. Using SIP, the FWSM can support any SIP VoIP gateways and VoIP proxy servers. SIP and SDP are defined in the following RFCs. • SIP: Session Initiation Protocol, RFC 2543 • SDP: Session Description Protocol, RFC 2327 Supporting SIP calls through the FWSM requires inspection of signaling messages for the media connection addresses, media ports, and embryonic connections for the media. While SIP signalling is sent over a well-known destination port (UDP/TCP 5060), the media streams use dynamically allocated ports. Also, SIP embeds IP addresses in the user-data portion of the IP packet and SIP inspection applies NAT for these embedded IP addresses. The following limitations and restrictions apply when using PAT with SIP: • If a remote endpoint tries to register with a SIP proxy on a network protected by the FWSM, the registration fails under very specific conditions, as follows: - PAT is configured for the remote endpoint. - The SIP registrar server is on the outside network. - The port is missing in the contact field in the REGISTER message sent by the endpoint to the proxy server. 22-76 Catalyst 6500 Series Switch and Cisco 7600 Series Router Firewall Services Module Configuration Guide using ASDM OL-20748-01
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