An overview of the Citadel BBS

The Private Stronghold

Chat in the Citadel

Text chat is an area where Citadel definitively does not shine, but the option is there. The left sidebar has a Chat section that allows users to chat in real time. Additionally, an XMPP client, such as Pidgin, can be used for chatting. Citadel offers an XMPP service on port 5222 by default.

The main downside is that the XMPP interface only allows person-to-person chat; group chat is not supported through this protocol, although it is possible through the web interface.

Other Features

In theory, Citadel supports Network News Transfer Protocol (NNTP). Regrettably, tests show that the feature does not work. According to the developer, the feature was never fully implemented.

The contacts and calendar systems are available, both in the web interface and by the GroupDAV protocol, which is interesting because it allows users to manage address books and calendars with common desktop tools, like KOrganizer or Kontact. A noticeable miss is the lack of support for the CardDAV and CalDAV protocols. Sadly, most users will be stuck with the web interface for these features, because GroupDAV support was not very reliable during tests.

True to its roots as an old school BBS system, Citadel can be used over SSH and Telnet. Setting up this configuration is a bit involved. The project website offers some instructions for performing a manual install.


Citadel is a nice bundle that includes a bit of everything required to satisfy the communication needs of a group of friends, a club, or a small organization. The mailing list functionality alone is a good reason to consider trying Citadel. However, it looks like Citadel is a jack of all trades and does not manage to excel in most of the tasks it performs.

The Contacts and Calendar functionality are a bit disappointing, so administrators in need of these services should look elsewhere. Nextcloud [6], for example, supports both CalDAV and CardDAV, very useful features Citadel lacks, and will integrate easily with desktop and mobile clients to allow shared contacts and calendars.

The whole Citadel experience feels a bit fiddly. Configuring the server to send and receive email properly is not very intuitive. (See the "Email Connectivity" box.) Although it is much easier than running a full-featured email service stack, an organization with more than a score of users might consider installing a complete email package suck as iRedMail [7].

Email Connectivity

An email server requires:

  • a static, reputable IP address,
  • a mail exchanger (MX) entry in the DNS record of your domain, and
  • a Sender Policy Framework (SPF) entry in the DNS record of your domain.

Theoretically, it is possible to run an email service from a dynamic IP with dynamic DNS (Figure 12), but in practice it can be troublesome and might cause your email to be rejected by other email providers.

Figure 12: Example DNS entries for a service capable of delivering and receiving email.

Setting the DomainKeys Identified Mail (DKIM) authentication method for the server and the domain could be beneficial. Citadel does not provide a DKIM service, but it can be set up separately. The Citadel website provides some hints [8].

That said, Citadel shines at its original purpose: being a forum in which members can initiate discussion threads and respond to questions posted by other people. The Floor and Rooms paradigm might sound strange at first, but once the workflow is understood, it leads to a very productive use of the BBS.

Those who want to try out the software can visit the official Citadel instance [9], which is also a good place to find support.

The Author

Rubén Llorente is a mechanical engineer, whose job is to ensure that the security measures of the IT infrastructure of a small clinic are both legally compliant and safe. He is also an OpenBSD enthusiast and a weapons collector.

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