This isn’t the most interesting of posts, but a good “note to self” for future reference. If not disabled, SSHD will try to do a slow reverse lookup of the IP address of the client causing for an unnecessary delay during authentication. I often run into trouble with this when creating a new install of Linux or FreeBSD.
To disable it, in the file /etc/ssh/sshd_config add the line below:
UseDNS no