I've defined a custom port for SSH within /etc/ssh/ssh_config
on my ubuntu-server installation and it is still accepting SSH on port 22 after rebooting the server.
Is there something else I need to do other than....
Host *
PermitRootLogin no
Port 6685
Protocol 2,1
SendEnv LANG LC_*
HashKnownHosts yes
GSSAPIAuthentication yes
GSSAPIDelegateCredentials no