Bug #112 was fixed early on for the rexloginmodule.cs so that one
could have modrex'd opensim behind a router. It appears that 
recent changes to the rex login module (i.e, subtracting 2000 for
internal port references used by modrex) have broken this, and now
I am unable to authenticate since the rex authentication compares
my external IP with that of the router (i.e., 192.168.1.1) itself.

The means to replicate this bug:

 1. use a common router (i.e., linksys) to link your computer to
    the Internet
 2. use the external IP as obtained through a web service or
    create a dynamic dns address
 3. when installing opensim, note that entering this external ip,
    and using this external IP in the SL client works.
 4. when building in modrex, and using the rex client, authentication
    of the sort:  user@<the external ip> along with the password fails
    because the rexlogin authentication procedure compares the wrong
    addresses

In the authentication window, here is the progress. I have replaced
my external dynamic dyns name with "<my external ip>"

12:18:12 - [HTTPD]: Starting up HTTP Server
12:18:12 - Enter help for a list of commands
12:18:12 - Authentication# :
12:18:12 - [HTTPD]: Starting http listener
12:21:14 - [LOGIN]: Authenticating Meta Phorz
12:21:14 - -------------------------------------------
12:21:14 - CLIENT LOGGIN IN TO SIM: metaphorz@<my external ip>:9000
12:21:14 - -------------------------------------------
12:21:14 - [SimLoginChecker]: Failed to authenticate sim from 192.168.1.1:8013
a
ddress corresponding to uid is <my external ip>
12:21:14 - [SimLoginChecker]: No corresponding dns addresses found
12:21:15 - [LOGIN]: server_ip_check failed
12:21:29 - [LOGIN]: Authenticating Test User