This question might reflect my misunderstanding of how NAT works.
(Well, considering that I think it works by magic, I suppose that that
is inevitable that I misunderstand.)
I am getting some outgoing packets occasionally blocked that should be
allow through. Here is an example log entry (line broken for
ipmon: 11:07:08.443851 sis0 @0:15 b
192.168.1.51,63864 -> 18.104.22.168,993 PR tcp len 20 101 -AFP IN
I am not having any user experienced difficulties with reaching port
993 on that remote host from inside my LAN at 192.168.1.51. It seems
that only the occasional packet is blocked.
I haven't been able to check systematically (syslogd on OS X sucks),
but my impression is that this is only happening with IMAP and IMAPs.
The only outgoing rules I have are to block ports 137-139,
Any insight into this would be welcome. Also I'd like to get
recommendations for good books on packet filtering firewalls including
Jeffrey Goldberg http://www.goldmark.org/jeff/