Routing problems

Andrew Haley aph at redhat.com
Thu Feb 18 10:50:24 UTC 2010


On 02/18/2010 10:01 AM, Rick Sewill wrote:
> On Thu, 2010-02-18 at 07:31 +0100, j.halifax . wrote: 
>> Hi All,
>>
>> Could you please help me with routing in the LAN default GW box?
>>
>> I have 
>> eth0 connected to Internet 
>> eth2 to internal LAN 10.255.250.0 
>> LAN default GW is 10.255.250.37
>> eth3 connected to other LAN

What is the address of the subnet "other LAN" ?

There seem to be two more subnets, 192.168.180.0 and 172.17.0.0.

Andrew.



>> Route in the default GW (10.255.250.37):
>>
>> Destination       Gateway           Genmask         Flags Metric Ref  Use Iface
>> 192.168.180.0   *                       255.255.255.0   U      0      0        0  eth3
>> 10.255.250.0     *                       255.255.255.0   U      0      0        0  eth2
>> link-local           *                       255.255.0.0      U     1003   0        0  eth0
>> link-local           *                       255.255.0.0      U     1004   0        0  eth2
>> link-local           *                       255.255.0.0      U     1005   0        0  eth3
>> 172.17.0.0       192.168.180.100  255.255.0.0      UG    0      0        0  eth3
>> default             dsl-router            0.0.0.0             UG    0      0        0  eth0
>>
>> >From the LAN default GW (10.255.250.37) 
>> - I can ping 172.17.1.50:
>>   PING 172.17.1.50 (172.17.1.50) 56(84) bytes of data.
>>   64 bytes from 172.17.1.50: icmp_seq=1 ttl=253 time=5.62 ms
>>   64 bytes from 172.17.1.50: icmp_seq=2 ttl=253 time=3.29 ms
>>
>> >From other boxes in the same LAN (e.g. 10.255.250.38)
>> - I cann't ping 172.17.1.50
>> - I cann't traceroute 172.17.1.50: It goes to LAN default GW 
>>   10.255.250.37 and then to its default GW dsl-router on eth0
>>   instead of eth3 (so that the routing rule for 172.17.0.0 doesn't 
>>   match for 172.17.1.50)
>>
>> Can anybody help pleasee?
>> Thank you so much!
>> jh
>>
> 
> Your problem has me stumped.
> 
> The only thing I can think of is to ask how iptables is set up.
> 
> I think you have iptables doing masquerading to the eth0 interface.
> The masquerading shouldn't be the problem.
> 
> Are you doing anything special with packets coming in eth2 in iptables?
> 
> I assume 10.255.250.38 can ping the Internet so you have routing set up.
> 
> I can't think of anything else to check at this moment.
> 
> Hopefully others will have better suggestions and ideas where to look.
> 
> 
> 



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