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.
Conspy allows a (possibly remote) user to see what is displayed on a Linux virtual console, and to send keystrokes to it. It only known to work with Linux. It is rather like VNC, but where VNC takes control of a GUI, conspy takes control of a text-mode virtual console. Unlike VNC, conspy does not require a server to be installed prior to being used.
poplimitd is a daemon process that monitors a server maillog file for POP3 or IMAP connections. Using configurable settings it monitors the rate of logins based on the user account and IP address. If it finds excessive usage, it will send a preconfigured email with the users information to that user asking them to stop. On servers that suffer from high POP3/IMAP load, this can dramatically modify user behaviour and limit POP and IMAP connections and load.
Braa is a tool for making SNMP queries. It is able to query hundreds or thousands of hosts simultaneously, while being completely single-threaded. It does not need any SNMP libraries, as it is equipped with its own SNMP engine. However, it's good to have a complete SNMP package including "snmptranslate" installed somewhere, because for speed reasons, there is no ASN.1 parser in Braa, and all the SNMP OIDs need to be specified numerically.
SquiDeral is an easy to use, configurable Web-based interface program for presenting the statistics created by squid cache proxy daemon in a "human-readable" format. It has an option to disable and limit the access to several hosts of your network, using ARP to make bogus records in the ARP table of the machine running squid, but the method can be changed by editing a file.