HCoop is running a closed registration Jabber server.
We are using ejabberd with the PAM authentication method. This means that your Kerberos password is now your Jabber password, and that every HCoop member has an account.
We have file uploads enabled, allowing files up to 100MiB each with a 30 day auto-expiry and 1GiB quota. If you need to share larger files or for extended periods of time, you should be sharing it using the web server instead.