Does the outgoing balance example work?

Paul J. Pathiakis pathiaki at pathiaki.com
Wed Dec 22 11:16:06 PST 2004


Hi,

	I'm trying to get pf to load balance outgoing on two outbound lines (cable and dsl).
My pf.conf is based on the example from the pf faq at www.openbsd.org.  I've changed
parameters to match my machine and I still can't get it to load balance outgoing 
connections on my machine.  As soon as I enable the route-to rules for balancing, my
web browser stops working and quite a few other utilities stop working.  It connects 
to the site but the response never comes back.  Is it possible that nat isn't working 
correctly?  Is it possible that the return addresses aren't getting correctly set?  
How do I troubleshoot this?  The example (below) seems  pretty straight forward.  
I've enabled my pflog (made sure every filter is logging).  
I can check states with pfctl commands.  I just can't see what's wrong.  Is there anything
that I'm missing (Please note that I changed the "default block all" to pass in all and pass
out all.

thanks!

Paul P.

lan_net = "192.168.0.0/24"
int_if  = "dc0"
ext_if1 = "fxp0"
ext_if2 = "fxp1"
ext_gw1 = "68.146.224.1"
ext_gw2 = "142.59.76.1"

#  nat outgoing connections on each internet interface
nat on $ext_if1 from $lan_net to any -> ($ext_if1)
nat on $ext_if2 from $lan_net to any -> ($ext_if2)

#  default deny
#block in  from any to any
#block out from any to any
pass in from any to any
pass out from any to any

#  pass all outgoing packets on internal interface
pass out on $int_if from any to $lan_net

#  pass in quick any packets destined for the gateway itself
pass in quick on $int_if from $lan_net to $int_if

#  load balance outgoing tcp traffic from internal network. 
pass in on $int_if route-to \
    { ($ext_if1 $ext_gw1), ($ext_if2 $ext_gw2) } round-robin \
    proto tcp from $lan_net to any flags S/SA modulate state
#  load balance outgoing udp and icmp traffic from internal network
pass in on $int_if route-to \
    { ($ext_if1 $ext_gw1), ($ext_if2 $ext_gw2) } round-robin \
    proto { udp, icmp } from $lan_net to any keep state

#  general "pass out" rules for external interfaces
pass out on $ext_if1 proto tcp from any to any flags S/SA modulate state
pass out on $ext_if1 proto { udp, icmp } from any to any keep state
pass out on $ext_if2 proto tcp from any to any flags S/SA modulate state
pass out on $ext_if2 proto { udp, icmp } from any to any keep state

#  route packets from any IPs on $ext_if1 to $ext_gw1 and the same for
#  $ext_if2 and $ext_gw2
pass out on $ext_if1 route-to ($ext_if2 $ext_gw2) from $ext_if2 to any 
pass out on $ext_if2 route-to ($ext_if1 $ext_gw1) from $ext_if1 to any 



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