From MIXXnet Wiki
Cerebrum is a MIXXnet server located in Groningen, The Netherlands. It is operated by Peter Kruit (Revox).
Cerebrum supports full SSL connectivity (traffic from user to server and traffic from server to hub is encrypted), and is included in the round-robin "irc.ssl.mixxnet.net".
Address (IPv6): cerebrumv6.nl.eu.mixxnet.net
Ports: 6667, 6697 (SSL)