If your server includes IPMI you could use that as a back-door to access the system when it has no network access. Or if your system has two NICs you could wire them both up with different IP addresses, so if you break one you can still connect on the other.
Otherwise, yeah, if you screw up the config and bring down the network on the system, you can't connect over the network anymore. I suppose you could implement a little script to babysit things while you try to reconnect. So instead of modifying the config by hand, instead you invoke a script which makes a backup of the existing config, opens up the config for you to edit, and when you're done it issues a network restart, sleeps for 60 seconds, restores the backup, and issues a network restart again. Then it's up to you to reconnect within 60 seconds and kill the script, otherwise the settings will revert to their previous values.
Last edited by suicidaleggroll; 03-11-2015 at 11:20 AM.