First go for brontos tip.
If that doesn't help/suit your needs, take a look at perldoc -f alarm and in perldoc perlvar search for %SIG
regards,
tomte
Edit:I received downvotes for this node
I'd like a cb-/msg or an answer on why.
A quick glance, before I wrote this node, into IO/Socket.pm suggested that the timeout is implemented, as it should be, using the correct calls to the underlying OS, and not a brute-force approach like
alarm.
I wrote this tip, because there are circumstances where a socket timeout may just not work (mostly OS related, me thinks), but
alarm will.