The IP address you want to set is in the TCP/IP envelope that the HTTP request header arrives in. You can't get at this from LWP.

To forge an IP address, you may need some way to build and ship your own TCP/IP packets. Perhaps someone with more knowledge of network protocol stacks can speak to how you might do this. Details will vary depending on what OS you're using.

You'll need to adjust the parameters that IO::Socket::INET creates the connection socket, adding LocalAddr to be something like one of the other addresses aliases for your host.

Be aware that you can only set this to one of the addresses that your host understands: you won't be able to set it to an address that would not have been routed to your host in the first place. (And that is as it should be: the TCP protocol is a two-way street, and the packets have to come back to you with a valid return address.)

I see some code in LWP::Protocol::http in the _newsocket subroutine that looks like it could be hooked in to add the appropriate values to the IO::Socket::INET call. But I've not used it directly. It might be as simple as setting @LWP::Protocol::http::EXTRA_SOCK_OPTS to ("LocalAddr", $yourhostalias) just before you issue each request. But again, that would have to be some address that is ifconfig'ed as being one of your IPs.

-- Randal L. Schwartz, Perl hacker