| Summary

| This module has covered the basics of the PIX Intrusion Detection System (IDS). Business transactions conducted over the Internet have increased tremendously over the years, as have the use of special protocols designed to facilitate various applications. Firewalls allow corporations to keep their internal networks secure from potential threats, without compromising on-line business transactions.

One of the primary limitations of traditional firewalls was that they did not pass traffic using protocols that utilized dynamically assigned source and destination ports or dynamically assigned IP addresses. Many of these protocols, such as FTP, HTTP, H.323, and SQL*Net are common protocols that businesses regularly use for communication. Modern firewalls, such as the PIX Security Appliance, have been designed to cope with protocols and applications that use dynamically assigned ports and IP addresses.

The module began with a review of advanced protocol handling, and how the PIX Security Appliance can be configured via a series of fixup commands to support specific protocols. Among these protocols are the advanced protocols used for multimedia support, real-time streaming protocols, and the protocols required to support IP telephony. These protocols include RTP and H.323. Some of these protocols operate over two channels, each of which have different access requirements.

A series of attack guards were presented next. These are special techniques that can prevent many problems that surround popular services such as e-mail and DNS. The methods of intrusion detection were also discussed, and the methods of configuration for PIX Security Appliances were explained. When a packet must be rejected, the process is called shunning. Shunning was discussed, along with configuration examples.

System logging can be configured to give administrators the information required to identify problems and attacks. Syslog files can be stored in a buffer, or sent to an external logging server. SNMP can also be used to monitor and manage PIX Security Appliances.