in reply to how do I get a website visitor's host address

this isn't Perl related, is it?
But anyway, try digging into the host name lookup :)
dig xxx.xxx.xxx.xxx host xxx.xxx.xxx.xxx nslookup xxx.xxx.xxx.xxx
and there are more possible ways.

"We all agree on the necessity of compromise. We just can't agree on when it's necessary to compromise." - Larry Wall.