PF route-to behavior

Alexandre Biancalana ale at seudns.net
Mon Mar 12 17:48:08 UTC 2007


Tom Judge wrote:
> Alexandre Biancalana wrote:
>> Tom Judge wrote:
>>> Alexandre Biancalana wrote:
>>>> Tom Judge wrote:
>>>>> Alexandre Biancalana wrote:
>>>>>> Hi List,
>>>>>>
>>>>>>
>>>>>> I´m doing a firewall setup using 6-STABLE + PF with two internet 
>>>>>> links but I can't do the route-to rule function as I need.
>>>>>>
>>>>>>
>>>>>>          (default gw)    ______
>>>>>>  Link A <-----------> |int A  |
>>>>>>                                  |           |
>>>>>>  Link B <-----------> |int B  |
>>>>>>                                  |______|
>>>>>>                              FreeBSD FW
>>>>>>
>>>>>> A simple thing that I need to do is test the two Internet links 
>>>>>> to know if they are up or not. To do this I could ping or connect 
>>>>>> tcp ports on some external ips thought each link, using nc and 
>>>>>> hping I tried do this generate connections/packets from each 
>>>>>> network interface connected to each link but the packets always 
>>>>>> go out by the interface indicated by machines default route.
>>>>>>
>>>>>> I tried to add this rules in pf to force packets out by the right 
>>>>>> interface based in your source address, but this does not work, 
>>>>>> and the packets generated with ip of int B are going out by int A.
>>>>>>
>>>>>> pass out log on $int_a route-to ( $int_b $int_b_gw ) from $int_b 
>>>>>> to any
>>>>>> pass out log on $int_b route-to ( $int_a $int_a_gw ) from $int_a 
>>>>>> to any
>>>>>>
>
>
>
> My mistake,  I only looked at the header of the ping man page.
>
> These are the rules that I would use in that situation:
>
> if_a=em0
> ip_a=192.168.0.2
> gw_a=192.168.0.1
> net_a=192.168.0.0/24
> if_b=em1
> ip_a=192.168.1.2
> gw_a=192.168.1.1
> net_a=192.168.1.0/24
>
>
> pass out log on $if_a route-to ( $if_b $gw_b ) from $ip_a to ! $net_b
> pass out log on $if_b route-to ( $if_a $gw_a ) from $ip_b to ! $net_a 


The difference is that my rules are for internet traffic, I don't have 
fixed destinations....




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