Since 1988 or so, the Unix version of Citadel, and since 1981, its DOS and CP/M predecessors, have been the choice for people wanting to start a community site on the Internet or on dialup. From its beginnings as a simple, easy to use bulletin board system, though, Citadel has grown to become much more.
Today Citadel supports most every major communications protocol you can think of, all by itself, without the help of other programs. It does SMTP, POP3 and IMAP for e-mail, for instance, handling multiple domains and virtual domains without blinking. It speaks natively to SpamAssassin without using any outside libraries. It includes LDAP directory support.
And it has its own lightweight, streamlined Web server. You don’t even need Apache. The server handles both normal HTTP and secure (HTTPS) connections easily, generating its own certificates or using those provided by your favorite certificate authority. In addition to the rooms (forums) which make up the core of Citadel, the Web server provides Web mail service, as well as calendaring and scheduling.
Oh, I forgot calendaring and scheduling? I’m sorry. Citadel does that too, using standard iCal/vCal objects. And it speaks GroupDAV.
And most everything is built in. No sendmail, postfix, dovecot, cyrus, etc., to mess with. Citadel takes care of it all for you. (OpenLDAP turns out to be much better than anything we could code up, so that is external.) Install, set it up, and forget it.
Yes, forget it. Citadel also does its own maintenance, with daily scheduled jobs. In the rare event of a crash, Citadel recovers itself if needed, too, minimizing downtime. Citadel restarts and recovers so fast, Web-connected users may not even realize anything happened. It just continues working.
Citadel installations are capable of handling over 1,000 simultaneous users on old hardware, and many more than that on the good stuff. And if you do happen to run into a hardware limit, throw in another server. The two Citadel servers will talk to each other and keep everything in sync. Still not enough? There’s no limit to how many Citadels you can have. You can even create an extranet Citadel to connect your partners and vendors to people and information on your Citadels that you designate.
So why haven’t you heard of Citadel before?
For one thing, the Citadel developers are working hard on the next major release, which will be version 7. This version promises a Python interface, making the server and client entirely scriptable and extensible via simple Python scripts. Say goodbye to Bloated Goats. Building custom applications is about to get easy.
Second, Citadel hasn’t actively sought too much publicity. Sure, there’s been the occasional /. posting, but mostly the developers have been placing their primary focus on delivering top notch software.
Now you’re in on the secret. Sick of sendmail’s security bug of the week? Exchange crashed again and took everyone’s calendar with it? Microsoft Outbreak let another virus into the intranet again? Want your email and calendaring to Just Work? With a nice web interface for the road warrior executive types? It’s time to take a good look at Citadel.