The Hacker Quarterly. This magazine used to be a little more on the fringe than
it has been lately, but still an excellent resource.
Don't waste your time with conventional search engines looking for the "toolz" of the trade. This site is a huge search engine for computer security related material, and is updated daily. You can run a search on Astalavista directly from this site by using the
search bar at the bottom of this page.
A great no-nonsense underground page. Their disclaimer: "ATTRITION may use language or ideas that are unsuitable to you. ATTRITION staff, system, and respective pets are NOT upbeat people. Deal."
Cult of the Dead Cow
One of the more famous Hacker Groups. These guys are brilliant and put a lot of pride into their work. Under-estimate them at your own risk. Their latest project "BackOrifice" has put them in the media spotlight again.
A great source of underground links. Check out their Top 50 Security Links Page
Digital Avatar's Matrix
Another exceptional site.
One of the best sites on the web. Great File Archive with Tools and Utilities. And it's updated frequently.
The infamous Silicon Toad has joined this group, and the site is being redesigned to be the best network and systems security site on the web. Phase I should be done early 2000.
Another great site. Lots of information, file downloads, and resources. This site has been around a while and does a great job.
Historic List of Underground files and Publications.
L0pht Heavy Industries
The guys that brought you L0phtcrack and got everyone's attention. They work very hard at what they do, and they do it well. Check their advisories often. If it's posted here, a hacker may be trying it on your network within hours.
Nomad Mobile Research Centre
"Simple Nomad" as he calls himself, runs a first-rate site that is well organized and easy to use. This is easily one of the best Hacker/Security Pages on the web, and is a little "friendlier" than most.
The original Underground No Holds Barred Hacker Journal. Some of the material in the archives is dated, but every serious security specialist has read them.