Networking in OS X
Unix on Panther: Accessing the Internet: A useful, elementary introduction.
Security
Exploring the Mac OS X Firewall: Useful article on doing more with the firewall built in to OS X.
Setting up firewall rules on Mac OS X 10.1 -- More sophisticated shell script with good commentary. Building your own personal firewall -- Useful sets of rules for securing the machine.SSH
Setting up tunneling with keys.
Apple Security Update 2004-06-07.
Fix for Slow SSH Logins: From OS X Hints, a useful note about some possible network problems in Tiger (OS X 10.4) that can cause delays during ssh login and other problems.
Enable postfix in Tiger (OS X 10.4): A useful note in MacOSHints.
“Although postfix seems to be configured to deliver locally generated mail out of the box in Tiger, it takes a few modifications to enable the SMTP daemon, and the required modifications are different from those for Panther.”
802.11
D-Link DI-713P and Mac OS X.
iStumbler for Mac OSX: "iStumbler is a free, open source tool for finding 802.11b & 802.11g wireless networks. iStumbler combines a compact Aqua user interface with visual feedback of signal strength and encryption." Only works with Apple's Airport card.