[Enhancement]: Add ability to set ACLs for router connections

[owendelong]

After turning on the FORT validator, I get lots of log messages about routers trying to connect and validate from addresses I don't recognize.

I've now set up packet filters to kill off these unwanted connections, but it would be nice if a simple permissive ACL could be expressed in the config.json file, similar to BIND and many other daemons.