[CentOS] Routing issue between 2 LANs

Sun Dec 19 22:15:11 UTC 2010
Les Mikesell <lesmikesell at gmail.com>

On 12/19/10 4:08 PM, José María Terry Jiménez wrote:
> Les Mikesell escribió:
>> On 12/19/10 2:30 PM, Jose Maria Terry Jimenez wrote:
>>
>>>>>>> This doesn't make much sense without a route.  Can you try a traceroute to the
>>>>>>> fedora box address from the 192.168.236.80 box to see how/why it gets there
>
>>>>>>> Hope it helps (all addresses are 192.168. Trimmed to compact the schema):
>>>>>>>
>>>>>>>
>>>>>>> ----------      ----------     -----------
>>>>>>> ! 1.3    !------!1.100   !     !gw 236.21!
>>>>>>> ! gw 1.1 !   !  !  236.74!-----! 236.80  !
>>>>>>> ----------   !  ! gw 1.1 !  !  -----------
>>>>>>>                 !  ----------  !
>>>>>>>                 !              !
>>>>>>>             [Router1]       [Router2]
>>>>>>>
>>>>>>> Router 1 is a PFSense and its IP is 192.168.1.1
>>>>>>> Router 2 is "something" (it is managed by other person, and i think is
>>>>>>> somekind of win server) and IP is 192.168.236.21
>>>>>>>
>>>>>>>
>>
>> This still doesn't explain why the 192.168.236.80 box can return packets to the
>> fedora at 192.168.1.3 when you said it didn't have a route going through
>> 192.168.236.74.   Can you check what routes you do have on 192.168.236.80 and
>> traceroute from there to 192.168.1.3?
>>
>>
> Apologies by confusing you. I forgot that "the other" CentOS had 2 NICs, this is
> the machine where i began these tests. It's in a remote site and now when
> listing the routes remembered that.
>
> It's conected to the 1. network with a second NIC and IP: 192.168.1.102. Replies
> must be return by that iface, really?

Yes, with rare exceptions routing always happens with each hop making the 
decision to use the interface that has the best route towards the destination, 
and that would have a route automatically added for anything within the netmask.

-- 
   Les Mikesell
    lesmikesell at gmail.com