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-   -   [SOLVED]Force routing of packets coming from the same subnet (http://www.linuxquestions.org/questions/linux-networking-3/%5Bsolved%5Dforce-routing-of-packets-coming-from-the-same-subnet-4175443379/)

genese 12-29-2012 10:31 AM

[SOLVED]Force routing of packets coming from the same subnet
 
Hello All,

My setup :

ROUTER : 10.10.10.1/24

HOST-1 : 10.10.10.10/24 default gw : 10.10.10.1

HOST-2 : 10.10.10.20/24 default gw : 10.10.10.1

Don't ask me why (at least before you have solved my problem ;-), I want to make HOST-1 & HOST-2 communicate via ROUTER.

I have added specific routes on each HOST :

HOST-1 : route add 10.10.10.20 via 10.10.10.1

HOST-2 : route add 10.10.10.10 via 10.10.10.1

The problem is that ROUTER replies with ICMP-Redirects.

How do I force ROUTER to route this traffic ?

ROUTER is a "Ubuntu 10.04.3 LTS" box.

TIA for your help

bijo505 12-29-2012 11:12 AM

Hi,

As per the ICMP protocol "ICMP Redirect is a mechanism for routers to convey routing information to hosts." I am pasting the content from the wiki below.

"Redirect
Redirect requests data packets be sent on an alternative route. ICMP Redirect is a mechanism for routers to convey routing information to hosts. The message informs a host to update its routing information (to send packets on an alternate route). If a host tries to send data through a router (R1) and R1 sends the data on another router (R2) and a direct path from the host to R2 is available (that is, the host and R2 are on the same Ethernet segment), then R1 will send a redirect message to inform the host that the best route for the destination is via R2. The host should then send packets for the destination directly to R2. The router will still send the original datagram to the intended destination. However, if the datagram contains routing information, this message will not be sent even if a better route is available. RFC1122 states that redirects should only be sent by gateways and should not be sent by Internet hosts."

Source: http://en.wikipedia.org/wiki/Interne...ssage_Protocol
http://www.wildpackets.com/resources...cp_ip/redirect

I hope this will help you
--
Thanks,
Bijo

genese 12-29-2012 11:31 AM

Quote:

Originally Posted by bijo505 (Post 4859084)
Hi,

The router will still send the original datagram to the intended destination.

Seems to work as advertised ;-) I've been blinded by the redirect messages.

Thank you.


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