remote ipfw module loading

Remote ipfw module loading dangerous, because, if your firewall rules don’t right, you can lose remote access to the server. To prevent this create at(1) job with `kldunload ipfw’ command. If module loaded and you can login to server remotly with ssh(1) client just delete this job.
Checklist:

• Create /etc/rc.firewall script with ipfw rules;
• Make sure about remote access using ssh(1) through firewall;
• Create at(1) job with `kldunload ipfw’;
• Load ipfw module using `kldload ipfw’;
• Try got access to allowed services;
• If all right delete at(1) job.