To allow root login via ssh on FreeBSD, edit sshd_config file:

sudo vi /etc/ssh/sshd_config

Find this line:

#PermitRootLogin no

and change it to:

PermitRootLogin yes

Now Restart sshd:

[email protected]:~ # /etc/rc.d/sshd restart
Performing sanity check on sshd configuration.
Stopping sshd.
Waiting for PIDS: 1698.
Performing sanity check on sshd configuration.
Starting sshd.