> From the documentation it's not clear to me whether this directive is > looking for an IP address of the Radius server to listen on, or if it > wants an IP address of the localhost from which to do the listening.
you are like asking to install freeradius on host A and listen radius authentication request on host B. otherwords, you asked the same question, so both are correct. i think you are confusing yourself from TO and ON. this auth bind address covers a radius server host which has multiple NICs each has separate ip address or even more virtual IPs on each NICs. - List info/subscribe/unsubscribe? See http://www.freeradius.org/list/users.html
