ProSum is a terminal based program that protects your files, sys_call_table, and IDT in a Tripwire-like way (all in user space, without kernel modules). In addition, a database with files could be encrypted with the Blowfish algorithm, and files that are protected can be stored on a secure/bastion host to later replace them. You can disable sys_call_table and IDT support for non-Linux systems. ProSum can run on any UNIX system with file protect mode (without IDT and sys_call_table support). ProSum is designed to run on the Linux x86 platform. This is not neccesary, but is recommended.
nefu (network fidelity utility) is a Unix daemon that monitors services over the network. It uses a "no false alarms" fault verification algorithm, and understands network dependancies. Natively-monitored protocols include ICMP echo (ping), SSH, IPP, DNS, HTTP, POP, NTP, IMAP, SMTP, and LDAP, as well as having facilities to execute external programs. Status pages are available via finger or the Web.
pv (Pipe Viewer) is a terminal-based tool for monitoring the progress of data through a pipeline. It can be inserted into any normal pipeline between two processes to give a visual indication of how quickly data is passing through, how long it has taken, how near to completion it is, and an estimate of how long it will be until completion.
Visual Interactive Datapipe (Vida) is an interactive visual datapipe for all *nix systems, which allows socket communications to be redirected over pipes. It features an ncurses interface that allows the creation of multiple datapipes, each supporting multiple connections. It is possible to sniff and log traffic in various ways, hijack piped connections, perform DNS hijacking on switched LANs, and much more.
Alarm Pinger (apinger) is a little tool which monitors various IP devices by simple ICMP echo requests. Unlike most Perl or shell script tools, it does not spawn processes or use much CPU time, and is ideal for when one wants continuous monitoring and fast response upon target failure. It is written in C and supports both IPv4 and IPv6.