'nat pass' not working in PF

[Andrew L. Gould]

I'm running pf in FreeBSD 5.3 on my laptop.  The filters for the local 
box work fine.  

I'm also working on a pc for a friend; but ran out of ethernet ports in 
my router.  This pc doesn't have a wireless adapter; so I adjusted my 
pf rules to use my laptop as a gateway for the pc.

I want my filters to remain intact for the laptop; but I want nat to let 
all the pc's traffic through.  (It has it's own firewall.) According 
the OpenBSD pf tutorial, adding the word 'pass' after 'nat' in the nat 
command will allow nat traffic to bypass the filter rules.  
Unfortunately, this doesn't seem to work.

If my default 'block log all' rule is left uncommented, I can only ping 
ip addresses (not host names that require nameservers).  No other 
activity passes through.  If I comment it out, all traffic passes; but 
my laptop is left unprotected.

Any advice?

The relevant lines from my pf rules follow:

ifdev = "ath0"
natdev = "fxp0"
scrub in all no-df
nat pass on $ifdev from $natdev:network to any -> $ifdev
icmp_types = "echoreq"
block log all
#other filtering rules follow

Thanks,

Andrew Gould