My sysadmin was trying to install libwww on a machine and got an infinite hang. The problem is that IO::Socket::INET on Linux has a bug in at least some versions of Perl, it does not properly honor a timeout parameter. See http://www.perlmonks.org/index.pl?lastnode_id=3989&node_id=34188 for a description of the issue. (I have also seen reports of similar problems in Windows arising from alarm() not working right.)
I would suggest that before performing the test you print a message that you are testing for whether the user is behind a firewall, say that this could have problems, and tell them a command line option they can use if they do to tell Makefile.PL that you are behind a firewall and it doesn't need to check that. Cheers, Ben
