I have been experimenting a bit with PF to get iChat to work,
unforuntately nothing to do I can't manage getting a video chat to
work... Maybe can someone help or have an idea what could be wrong ? I
have the following rules in my pf.conf just for iChat:

rdr pass on $ext_if proto udp from any to any port 16393:16402 ->
$int_mbp_ip port 16393:16402
rdr pass on $ext_if proto udp from any to any port 5060 -> $int_mbp_ip
port 5060
rdr pass on $ext_if proto udp from any to any port 5190 -> $int_mbp_ip
port 5190
rdr pass on $ext_if proto udp from any to any port 5678 -> $int_mbp_ip
port 5678
rdr pass on $ext_if proto tcp from any to any port 5190 -> $int_mbp_ip
port 5190
rdr pass on $ext_if proto tcp from any to any port 5220 -> $int_mbp_ip
port 5220
rdr pass on $ext_if proto tcp from any to any port 5222 -> $int_mbp_ip
port 5222
rdr pass on $ext_if proto tcp from any to any port 5223 -> $int_mbp_ip
port 5223
rdr pass on $ext_if proto tcp from any to any port 5298 -> $int_mbp_ip
port 5298

$ext_if is my external interface with external IP, $int_mbp_ip is my Mac
OS X 10.5 workstation.

Thanks
Regards