ccna 4 8.1.1.8

ccna 4 8.1.1.8.The Classic Firewall can also support connections with embedded NAT and PAT information and perform the necessary address translation. The Classic Firewall can block P2P connections such as those used by Gnutella and KaZaA applications. Instant messaging traffic such as Yahoo!, AOL and MSN, is also blocked.Classic Firewall provides 4 important features: traffic filtering, traffic detection, intrusion detection, and generation of audit and warning messages. Classic Firewall is the third generation of the CiscoIOS stateful firewall solution, the second generation being TCP established and self-reversing ACLoThe first Classic Firewall command was introduced to the CiscoIOS software in 1997. Compared to the TCPestablished and self-reversing ACL firewalls, the Classic Firewall is a significant improvement in all of the following areas.Monitoring the establishment of TCP connections.Tracking TCP sequence numbers.Monitoring UDP session information.Detecting DNS queries and responses.Detecting common ICMP message types. Support for applications that depend on multiple connections. Detecting embedded addresses. Detects application layer information.It is important to focus on the fact that Classic Firewall only provides filtering for protocols specified by the administrator; if not specified, existing ACLs will determine how to filter protocols and no temporary openings will be created. In addition, the classic firewall only detects and prevents attacks that traverse the firewall. It typically does not protect against attacks originating from protected networks, unless the traffic passes through an internal router with the CiscoIOS Firewall enabled.4.2.3.2 Operation of the Classic Firewall