[CentOS] Routing issue between 2 LANs

Sun Dec 19 22:27:45 UTC 2010
José María Terry Jiménez <jtj at tssystems.net>

El 19/12/2010, a las 23:15, Les Mikesell <lesmikesell at gmail.com> escribió:

> 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.
> 
Thanks by your help, now i understand this a bit better,

Best