"The way to keep giant companies from sterilizing the Internet is to make their sites irrelevant. If all the cool stuff happens elsewhere, people will follow. We did this with AOL and Prodigy, and we can do it again." – Maciej Cegłowski
Pleroma is an OStatus and ActivityPub compatible social networking server, compatible with GNU Social, PostActiv and Mastodon. It is high-performance and so is especially well suited for running on low power single board computers without much RAM.
Some general advice about life in the fediverse can be found here.
Installation
Log into your system with:
ssh myusername@mydomain -p 2222
Using cursor keys, space bar and Enter key select Administrator controls and type in your password.
Select Add/Remove Apps then pleroma. You will then be asked for a domain name and if you are using FreeDNS also the code for the domain which can be found under Dynamic DNS on the FreeDNS site (the random string from "quick cron example" which appears after update.php? and before >>). For more details on obtaining a domain and making it accessible via dynamic DNS see the FAQ. Typically the domain name you use will be a subdomain, such as pleroma.mydomainname.net. It will need to be a domain which you have bought somewhere and own and not one of the FreeDNS subdomains, otherwise you won't be able to get a SSL/TLS certificate for it.
Initial setup
The first thing you'll need to do is register a new account. You can set your profile details and profile image by selecting the small settings icon to the right of your name.
Once you have done that then you can disable further registrations from the Administrator control panel by going to App Settings then pleroma then Disable new account registrations. This may take a while because the app gets recompiled afterwards.
Mastodon user interface
If you prefer a Tweetdeck-style user interface, similar to Mastodon, then once you have registered an account navigate to /yourpleromadomainname/web and log in.
Blocking controls
The biggest hazard with Pleroma is that it's part of a public federated communications system. This means that conversations and replies from other servers may end up in your "whole known network" stream. The internet being what it is, some of these could be undesirable. You can block individual users or entire domains by going to the Administrator control panel and selecting Domain or User Blocking, then adding or removing entries. This blocks domains at the firewall level and also at the level of database and file storage.
If you want to block a particular user then select Block a domain or user and enter the user in the format username@domaintoblock (similar to an email address).