Anteater is a log analyser for MTA logfiles (such as those produced by sendmail and postfix). The tool is written in 100% C++ and is very easy to customize. Input, output, and the analysis are modular class objects with a clear interface. Currently, there are modules for reading the syslog format of sendmail and postfix that do up to eight useful analyses and write the result in plain ASCII or HTML, to stdout or to files.
fireparse is an ADMLogger plugin that emails a report of all packets that have been logged by the kernel's packet filtering subsystem (iptables/netfilter or ipchains). The report includes source and destination ports, direction, logged packet count, matched rule, and fully resolved host names (if available). The email report can be formatted to plain text or a colored HTML table.
Firewall Log Daemon is a program written in C which will watch for ipchains or iptables log alerts in realtime. The program will start a small daemon process that parses and resolves firewall logs by reading a FIFO that syslog writes to. It can queue a batch of alerts and mail them to you, or can be used in a script to crunch an existing log file or data stream. It features hostname, port, protocol, and ICMP type/code lookup, with output formatted by a user-defined template.
fwlogwatch is a packet filter and firewall log analyzer with support for Linux ipchains, Linux netfilter/iptables, Solaris/BSD/HP-UX/IRIX ipfilter, Cisco IOS, Cisco PIX/ASA, Netscreen, Elsa Lancom router, and Snort IDS log files. It can output its summaries in text and HTML and has a lot of options. fwlogwatch also features a realtime anomaly response capability with a Web interface.
log_analysis is a log file analysis engine that extracts relevant data for any of the recognised log messages and produces a summary that is much easier to read. It can be configured to recognize entirely new log types. log_analysis natively understands about 100 different kinds of syslog messages, as well as sulog and wtmp messages for Linux, Solaris, and OpenBSD. It also has optional continuous monitoring capabilities, with both text and GUI modes.