I think this is your problem, 2.0.30 still hasn't been fixed AFAIK, altho the
closest I got was to have the re-directiuons to go to the localhost correctly,
but it wouldn't re-direct to the appropriate port.
ie, if you used the command:
ipfwadm -a accept -I -P tcp -D 0/0 80 -r 3128
then you would find all the traffic destined for 0.0.0.0/0 80 instead going to
localhost 80 (NOT localhost 3128 as it should).
If anyone has seen a fix for this, then I would be happy to give it a go, but
the only solution I have yet found was to revert to 2.0.29.
Adam