Host Based Auditing Tools:
COPS, crack, Tiger, Tripwire, nfs_bug, probe_tcp_ports
Network Traffic Analysis Tools:
etherman, netlog, tcpdump, synsniff, tocsin, clog
Security Management Tools:
localmail, smrsh, npasswd, op, osh, passwd+, S4 kit, swatch, watcher, wuftpd
Network Auditing Tools:
ISS, SATAN, securscan
Secure Remote Access:
OPIE, RADIUS, S/Key, SSH, tacacs+