Article from http://seclists.org/pen-test/2000/Sep/0200.html

I assume you meant the usual network-based penetration test by that.
If you are asked to mess with a client’s pbx/vmb, physical security,
employees, etc… there are other techniques or hardware involved.
Most penetration tests are conducted in two phases: exploration and
exploitation.
I recommend you tailor a software ‘tool suite’ with those as
guidelines. Depending on your style, organizing tools this way may
or may not be efficient.
Below are examples biased towards Unix; perhaps an NT person has
suggestions for that platform.
Exploration and Analysis
- portscanners:
nmap (www.insecure.org)
- sniffers:
tcpdump (www.tcpdump.org)
ngrep (sourceforge.net/projects/ngrep)
dsniff (www.monkey.org/~dugsong/dsniff)
- vuln scanners:
vlad (razor.bindview.com/tools/)
whisker (sourceforge.net/projects/whisker)
- Samba, nbtscan, l0phtcrack & other tools for windows networks
- the inevitable custom code and scripts
Exploitation
- hunt (www.gncz.cz/kra/index.html)
- misc tools (www.ussrback.com, www.packetfactory.net)
- whatever is current from packetstorm/ussrlabs/bugtraq/etc.
for the targets.
This category is dynamic and typically contains unreleased
exploits, in-house code, etc. Its also the attack phase which
causes most ’script kiddies’ grief, as it requires a lot of creative
tweaking to avoid detection.
A portable computer and disc with various tools compiled for your platform
of choice is a good starting point for a network penetration kit.