Both the IP 127.0.0.1 and the users.undernet.org can be changed. Vampire just added HIDDEN_IP feature so you can change the ip (127.0.0.1) in conf. To change the users.undernet.org, just edit HIDDEN_HOST in your F-Lines (Feature Lines).
<snip> Just changes the apparent IP to 127.0.0.1 and the apparent hostname to <username>.users.undernet.org--the latter string is configurable via the features subsystem. </snip> ~reed UnderNet Spelling/Grammar Checker UnderNet Coder Committee Odd Guy Planetarion VirusFix Member/Helper/BotAdmin cyclebot Project Administrator