The reason why .shosts authentication does not work by default in more recent versions of FreeBSD is because ssh(1) is not installed suid root by default. To ``fix'' this, you can do one of the following:
As a permanent fix, set ENABLE_SUID_SSH to true in /etc/make.conf and rebuild ssh (or run make world).
As a temporary fix, change the mode on /usr/bin/ssh to 4555 by running chmod 4755 /usr/bin/ssh as root. Then add ENABLE_SUID_SSH= true to /etc/make.conf so the change takes effect the next time make world is run.