Lordy! That's a bit long!

I'd go for something like this:

my ($ip1, $port1, $ip2, $port2) =
  ($inLine =~ m|^from ([0-9.]+)/?([0-9]*) to ([0-9.]+)/?([0-9]*) on in
+terface$|)
[download]

(Untested but should be roughly right)

hth,
andy.

update: changed the delimiter for obvious reasons