HTTP

Configure berlin.ccc.de web server to send federation traffic to the matrix server:

server {
  hostname berlin.ccc.de;
  location "/.well-known/matrix/server" {
    default_type application/json;
    return 200 '{"m.server":"matrix.berlin.ccc.de:443"}';
  }
}

DNS

_matrix-fed._tcp.matrix.berlin.ccc.de.  IN SRV  10 0 443 matrix.berlin.ccc.de.
#_matrix._tcp.matrix.berlin.ccc.de.     IN SRV  10 0 443 matrix.berlin.ccc.de.
#_matrix._tcp.berlin.ccc.de.            IN SRV  10 0 443 matrix.berlin.ccc.de.
_matrix-fed._tcp.berlin.ccc.de.         IN SRV  10 0 443 matrix.berlin.ccc.de.
matrix.berlin.ccc.de.                   IN A     <IPv4>
matrix.berlin.ccc.de.                   IN AAAA  <IPv6>

Bots

register_new_matrix_user \
    -c homeserver.yaml https://matrix.berlin.ccc.de \
    --user_domain berlin.ccc.de \
    --user <YOUR_BOT> \
    --password <YOUR_PASSWORD>