$S = IO::Socket::INET->new(
   PeerAddr => "some.unreachable.ip:80",
   Proto => "tcp",
   Timeout => 1) or die "Couldn't connect: " . ($! ? $! : $@);

# this too:

$S = IO::Socket::INET->new(Proto=>"tcp", Timeout=>1);

$sin = sockaddr_in(80, inet_aton("some.unreachable.ip"));

$S->connect($sin) or die "Couldn't connect: " . ($! ? $! : $@);