ls4sweep is a tool intended for use as helper for removing old backups. A sweeping policy consists of a set of records that contains the number of intervals or a periods in days to retain. It checks creation or modification time of given files and displays names of those when they don't match the policy. The output can than be passed to rm.
Fallback-gw is a little script to be called via cron that checks availibility of neighbor routers using ping and activates backup routing on ping failure. It can be used as a stupid replacement for BGP/OSPF in a multihomed environment. It has been tested on FreeBSD and on Linux with iproute2.
SpamBlock counts attempts to establish a connection on port 25/tcp via tcpdump. When a host exceeds the allowed number of attempts per unit of time, it is added to a corresponding ipfw table and email notification is sent. Spamblock currently supports ipfw only, but it can be easily adapted for any firewall and OS. It can also be configured to watch multiple ports to prevent Telnet and SSH attacks in addition to SMTP.