Apache Web Server
Recent statistics show that Apache serves between 50 and 60% of the traffic on the world wide web. This is the home page
Slashdot Apache Page
Slashdot is probably the most popular news/editorial page for open source advocates and users. This page aggregates items of interest about the Apache Web Server.
Slashdot
This is probably the biggest open source (and linux in particular) news site on the net - lot's of good information and stories daily.
FreeBSD
Free version of the Berkley variant of Unix. Runs some of the highest volume web/ftp servers on the Internet.
Linux.Org
Distrobution neutral site devoted to Linux advocacy and education. Good place to start if you don't know much about Linux.
Sendmail.Org
Sendmail comes in two flavors - free and commercial; functionally most are well served by the freeware version, but the commercial version has a formal support mechanism - for a fee of course:)
Sendmail.Net
Sendmail comes in two flavors - freeware and commercial; this is the official home of all of them.
Procmail
If you want to sort your mail, kill spam, send autorespond messages or just about anything else with your email - Procmail is for you.
QPopper
Qpopper is the most widely-used server for the POP3 protocol. This allows users to access their mail using any POP3 client. Qpopper supports the latest standards, and includes a large number of optional features. Qpopper is normally used with standard UNIX mail transfer and delivery agents such as sendmail or smail.
Squid
Squid is...
a full-featured Web proxy cache designed to run on Unix systems. It's free, open-source software,
the result of many contributions by unpaid volunteers and
funded by the National Science Foundation
Samba
Samba is an open source software suite that provides seamless file and print services to SMB/CIFS clients. Samba is freely available under the GNU General Public License
UW-IMAP
IMAP - the Internet Message Access Protocol - is a method of accessing electronic messages kept on a (possibly shared) mail server. This Web site is provides information about and access to IMAP-supporting software developed by the University of Washington (UW) as well as two IMAP-related mailing lists hosted by the UW. See the additional information section for more on IMAP.
Netcraft
Probably the most trusted and most oft-quoted Internet statistics companies. They basically keep track of who's running what software and report on it.
E-Soft / Security Space
For a quick glance at server 'market share', I like this page - it has a great big pie chart on the first page.
Snort
Snort is a lightweight network intrusion detection system, capable of performing real-time traffic analysis and packet logging on IP networks. It can perform protocol analysis, content searching/matching and can be used to detect a variety of attacks and probes, such as buffer overflows, stealth port scans, CGI attacks, SMB probes, OS fingerprinting attempts, and much more. Snort uses a flexible rules language to describe traffic that it should collect or pass, as well as a detection engine that utilizes a modular plugin architecture. Snort has a real-time alerting capability as well, incorporating alerting mechanisms for syslog, a user specified file, a UNIX socket, or WinPopup messages to Windows clients using Samba's smbclient.
Security Focus
If you only have time to go look at one site on Internet/Web security, this should be the one -- subscribe to the Bugtraq mailing list while your at it.
USSR is Back
USSR is a young company based in South America devoted to research about computer & networks security and software protection systems. One of the main objectives of USSR is to develop and implement new security and protection systems based on our knowledge and experience.
Linux Today
One of the 'Today' sites. Good aggregating point for Linux stuff.
PHP Home
OK, I'm a little biased here - I do about 90% of my development work in PHP, but compared to it's competition - Perl/ASP/ColdFusion, nothing.comes close in my opinion
ChiPHPug
Newly formed, we're still building members and programs - watch our site for updates!
BSD Today
One of the 'Today' sites - this one covers the various BSD flavors, Open, Net and Free.
PHP Builder
One of the better PHP sites - offers tutorials, code samples and editorial content.
CGI Resources
While I'm a big fan of PHP, Perl has been around 'forever' and I've written my share as well. This is one of the bigger and better CGI script sites.
Apache Today
Another of the 'Today' sites. This concentrating on Apache - news, education and advocacy.
Phorum
If you've looked at Mr. Wizard, you've seen Phorum - there is also a growing roster of other sites as well; it an SQL back end and PHP to run, but it's slick!
GNU Privacy Guard
GNUPG provides replacement functionality for PGP without any patented algorithim usage (RSA/IDEA)
PGP
PGP was ahead of the curve with email encryption and it's author took his lumps for being there. It's now a commercial product (and more) - there is a free alternative in GNUPG, but this is where it started.
Hank's Port Scanner
This was one of my internal scripts that I'd use for preliminary threat assessment when on-site with a client ... I cleaned it up, gave it a somewhat pretty face and started using it as a 'teaching script' in a PHP class to illustrate how to spawn a process and parse it's output.It uses the popular portscanner NMAP as it's engine -- it doesn't miss much!
MySQL
High speed SQL database ideal for web applications. Multiple platform support
PostgreSQL
Feature rich open source SQL database -- if you've outgrown MySQL from a feature standpoint, this is a good place to look.