DSL router when what I need is a bridge; ARP problem?

Vince Hoffman Vince.Hoffman at uk.circle.com
Thu May 29 03:03:49 PDT 2003

>      dsl line <---> Cisco 678 <-ed0-> freebsd <-de0-> local host
>    I naively picked up a Cisco 678 thinking it would do the trick.
>    However, even with CBOS 2.4.7 installed, it won't route out the
>    ethernet port -- only out the wan port.  e.g., if the 
> routing tables
>    in the cisco look like this:
> cbos#show route
>   ip           mask                   gateway      type  interface
>                a.b.c.d      DSAR  wan0-0
> <router-ip>    <>      <freebsd-ip> LAR   eth0
> <local-lan-ip> <>      <freebsd-ip> SAR   eth0

I'm no networking expert so hopefull if I say anything too silly then 
someone will correct me.

If i've understood you correctly you want to join two seperate physical
network segments on the same subnet using the freebsd box. 
Since the join is the Freebsd box then getting that to bridge the two
nics should work (assigning and IP to one if needed.)
Otherwise you'll need some more routes and to make things more complex, 
 a working example that I have in use (wanted to firewall a class c but
was supplied with a managed router as .1 and didnt want to use bridging.)
The router and firewalls routerside nic have a .252 netmask (subnet of
.1 and .2) the router (.1) has a static route of x.y.z.0/24 via .2 
(firewalls external nic) the firewall has .1 as 
its default route. rest of class c has firewalls other nic (.194 for 
no good reason) as default route.

Hope this helps

>    The router can ping anything on the local lan, sending its 
> request and
>    receiving its reply via the freebsd box; but if anything 

unless the freebsd box is bridging already not sure why that works.


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