Tom, That is not entirely correct. If you provide the X-Forward-For header AOLserver correctly logs this into the access.log. So it is probably only an omission.
As for the parameter suggested by Gustaf, that is fine with me as well, could you provide a full diff so we can actually TIP this? (though I cannot see why anyone would want the IP Address of the proxy when calling ad_conn peeraddr and if they want, they can still fallback to ns_conn peeraddr).
