Logcheck parses system logs and generates email reports based on anomalies. Anomolies can be defined by users with 'violations' files. It differentiates between 'Active System Attacks', 'Security Violations', and 'Unusual Activity', and is smart enough to remember where in the log it stopped processing to improve efficiency. It can also warn when log files shrink, and does not report errors when they are rotated.
trend is a general-purpose, efficient trend graph for "live" data. Data is read in ASCII format from a file or continuously from a FIFO, and is played in real-time into a multi-pass trend (much like a CRT oscilloscope or a strip chart). trend can be used as a rapid analysis tool for progressive or time-based data series together with trivial scripting.
Snortalog is a powerful Perl script that summarizes Snort logs, making it easy to view any network attacks detected by Snort. It can generate charts in HTML, PDF, and text output. It works with all versions of Snort, and can analyze logs in three formats: syslog, fast, and full snort alerts. Moreover, it is able to summarize other logs like CheckPoint, Netfilter, IPFilter, Packet Filter, Cisco PIX/ASA, NetScreen, TippingPoint, and Lucent BRICK in a similar way.