Trinux Source Links

Firewalls [FTP]
dante - an Open Source version of SOCKS [http]
ip_filter - BSDish packet filter/nat port for Linux [http]
ipfwadm - the standard (for now) Linux kernel packet filter [http]
ipchains - the upcoming standard for Linux kernel packet filtering [http]
SINUS - finally a buzzword compliant firewall for Linux [http]

Network Mapping [FTP]
axfr - sophisticated DNS transfer tool by ADM. [ftp ]
nmap - Fyodor's flexible network mapping tool. [http]
strobe - standard connect() scanner by Julian Assange
tcp_scan - tcp connect() scanner from SATAN
queso - OS fingerprinting tools by the Apostols [http]
rdns - does brute-force DNS querying on network address space
z0ne - small tool for performing DNS zone transfers [ftp ]

Packet Sniffing [FTP]
ethereal - gtk+ based sniffer, supports a large number of protocols and is
continually updated [http]
cold - sniffer providing support for a few protocols that none of the
others support [home]
ipgrab - tcpdump-based sniffer that provides output similar to snoop [http]

karpski - another gtk+ based sniffer [http]
libpcap - portable packet capture library that makes a lot of this stuff
possible [ftp site]
sniffit - best sniffer for capturing application-layer data [http]
tcpdump - the standard packet sniffer for Unix boxes [ftp]
tcpdump-smb - patch to provide support for NetBIOS over IP protocols [ftp]

Network Monitoring [FTP]
iptraf - nice curses-based network monitor with lots of pretty screens
[http]
netwatch - another curses based monitor that shows network activity
ntop - a great new monitoring tool with http browsing [ http ]

Miscellaneous Tools
neped - detect Linux promiscuous-mode NICs on your subnet [http]
spak - create arbitary TCP/IP packets [http]
ipsend - packet generator from the ipfilter package [http]
UCD-SNMP - UC-Davis SNMP implementation [http]