Layer-7 Packet Classifier for Linux 2007-07-27 (Pattern Definitions)

Layer-7 Packet Classifier for Linux is a packet classifier for Netfilter that identifies packets based on application layer (OSI layer 7) data. This means that it is able to classify packets as HTTP, FTP, Gnucleus, Kazaa, etc., regardless of ports.
It complements existing matches that classify based on port numbers, packet length, TOS bits, and so on. Combined with Linux QoS, it allows for full layer 7 packet shaping.
Main features:
- Patches for Linux 2.4 and 2.6
- Support for TCP, UDP and ICMP over IPv4
- Uses Netfilters connection tracking of FTP, IRC, etc
- Examines data across multiple packets
- Number of packets examined tunable on the fly through /proc
- Number of bytes examined tunable at module load time
- Distinguishes between new connections (those still being tested) and old unidentified connections
- Gives access to both Netfilter and QoS (rate limiting) features
- With the Netfilter "helper" match, you can distinguish between parent and child connections (e.g. ftp command/data)