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Re: Force use of outgoing IP address

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Subject: Re: Force use of outgoing IP address
From: Grant Taylor <gtaylor@riverviewtech.net>
Date: Fri, 01 Jun 2007 12:22:56 -0500
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On 06/01/07 11:42, Neil Russell wrote:
I have a linux router with 3 network cards in, each card has multiple
IP address's assigned. I want to route all aoutbound traffic TO a
destination port of $DESTPRT out of eth0 on its IPAddress of
10.0.0.2.

If you want ONLY the traffic that is destined to $DESTPRT to use the alternative IP, you will probably need to set up multiple routing tables similar in all respects except for the source IP used. Then you can use "ip rule" to decide which traffic uses the alternative routing table and source IP. I.e. everything by default uses the main IP address while only traffic destined to $DESTPRT uses the other IP. Is this what you are after?

So ALL traffic on the router with a destination address MUST go out
on eth0 and show its IP address as 10.0.0.2 even though the default
route is out via 10.0.0.1

Hugh? Are you saying you want all traffic leaving the system to have an IP address of 10.0.0.2 not 10.0.0.1? If this is the case, switch the first and second IP address in your configuration. I believe by default the system will use the primary IP address of an interface as it's default that it bind traffic to. I.e. eth0 verses eth0:1 / eth0:2. Though I'm not sure, it may choose the lowest IP address not the first one.

Hope thats clear and that someone can advise.

No, not really. I'm having trouble identifying which types of traffic you are wanting to change both up top and down below.



Grant. . . .


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