(RADIATOR) Auth port

[Dave Kitabjian]

Keep in mind that there is a port FROM which a packet is sent (which is
usually irrelevant and arbitrary) and there is the port TO which the
packet is sent (and on which the packet is received by the server). The
latter are "well known" (see /etc/services), do not normally change once
a server has begun, and must be open on firewalls that stand in front of
those servers in order to receive those packets. 

Also, since RADIUS normally uses UDP, there is no "connection" and so
the client (the NAS) must also have its ports accessible through any
firewall that may be in front of it.