'nat pass' not working in PF

J65nko BSD j65nko at gmail.com
Fri Jan 21 09:13:15 PST 2005


On Fri, 21 Jan 2005 08:20:45 -0600, Andrew L. Gould <algould at datawok.com> wrote:
> 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
How about something like this:
EXT_IF = "fxp0"
INT_IF = "xl0"

TCP_OUT = "{ ssh, www, https, smtp, pop3 }"
UDP_OUT = "{ domain }"
ICMP_OUT = "echoreq"

scrub in all no-df

nat on $EXT_IF from $INT_IF:network to any -> $EXT_IF

# -- default policy
block log from any to any

# -- LOOPBACK
pass quick on lo0 from any to any

# -- EXTERNAL 

# -- tcp
pass out quick on $EXT_IF inet proto tcp from any to any port $TCP_OUT
flags S/SA keep state

# -- udp
pass out quick on $EXT_IF inet proto udp from any to any port $UDP_OUT
keep state

# -- icmp
pass out quick on $EXT_IF inet proto icmp from any to any icmp-type
$ICMP_OUT keep state

# -- INTERNAL
pass on $INT_IF from any to any

=Adriaan==


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