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-   -   eth1 routes to eth2, but no the opposite (https://www.linuxquestions.org/questions/linux-networking-3/eth1-routes-to-eth2-but-no-the-opposite-851789/)

fdelval 12-22-2010 06:01 AM

eth1 routes to eth2, but no the opposite
 
Hello all

I have a debian distro, with 2 interfaces:

192.168.3.254 eth0
192.168.4.254 eth1

I currently have no iptables rules (i ran iptables -F, -X, -Z, -t nat -F......)

Of course, when a host in 192.168.4.x network send a ping to the 192.168.3.1 router, ping doesnt reach it.

Weird thing is, when a host in 192.168.4.x network send a ping to the 192.168.3.254 interface, ping reaches.

I say its weird, because when i do the opposite, a host in 192.168.3.x network send a ping to the 192.168.4.254 interface, ping doesnt reach.


maybe im paranoid, but it makes no sense.


Any tips?

acid_kewpie 12-22-2010 06:17 AM

sounds like there is not route on the machines in the 3 network to reach the 4 network. That is consistent in the statement that no traffic on the 3 network hits the router box when addressed to the 4 network

fdelval 12-22-2010 06:35 AM

Quote:

Originally Posted by acid_kewpie (Post 4199964)
sounds like there is not route on the machines in the 3 network to reach the 4 network. That is consistent in the statement that no traffic on the 3 network hits the router box when addressed to the 4 network


Seems an option to start the investigation, but, i only have one host in the .3 and .4 subnets:

i configured the server (the box with 192.168.3.254 and 192.168.4.254 IPs) to give DHCPs in 192.168.3 and 192.168.4 subnets.
When i unplug and plug the cable, the only host for proofs, gets 192.168.4.x or 192.168.3.x IP



SCHEMA

router 192.168.3.1 ----------192.168.3.3---------- 192.168.3.254 SERVER WITH DHCP AND PROBLEM 192.168.4.254 ---- 192.168.4.4


The 192.168.3.3 and 192.168.4.4 IP's belongs to the same host, deppending if i plug it to ona interface or another


Explaining that, when should i check the routes? in the server or in the client?






p.s. traceroute shows only 1 hop from 192.168.3.3 to 192.168.4.254
i thought it would be 2 hops, one to 192.168.3.254 and another from that to 192.168.4.254

fdelval 12-22-2010 07:51 AM

1 Attachment(s)
I managed to draw the schema










And this is the routing table

192.168.4.0........0.0.0.0...........255.255.255.0 .... u .... 0 ..... 0 .... eth1
192.168.3.0........0.0.0.0...........255.255.255.0 .... u .... 0 ..... 0 .... eth0
0.0.0.0 ........ 192.168.3.1...........0.0.0.0.... ug .... 0 ..... 0 .... eth0

fdelval 12-23-2010 04:16 AM

i also installed virtualbox, which creates a new subnet.... maybe its related?


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