Martin at 07:56, 5 July 2019

2019-07-05T07:56:44Z

← Older revision		Revision as of 07:56, 5 July 2019
Line 9:		Line 9:

	eth2: 10.10.0.131/24		eth2: 10.10.0.131/24
	eth3: 10.20.0.2/24		eth3: 10.20.0.215/24

	eth2 is primary and reponds to ping - eth3 does not.		eth2 is primary and reponds to ping - eth3 does not.
Line 18:		Line 18:

	<pre>		<pre>
	echo ~~13 eth3~~ >> /etc/iproute2/rt_tables		echo 1 webserver_vlan >> /etc/iproute2/rt_tables
	</pre>		</pre>

	=== Add a default route to this new table going out eth3 ===		=== Add a default route to this new table going out eth3 ===
			* point to gw on that network
	<pre>		<pre>
	ip route add default via 10.20.0.1 table ~~eth3~~		ip route add default via 10.20.0.1 dev eth3 table webserver_vlan
	</pre>		</pre>

	=== Add a policy rule to use this new table for packets with source address of eth3's IP ===		=== Add a policy rule to use this new table for packets with source address of eth3's IP ===
			* Use ip of eth3 here.
	<pre>		<pre>
	ip rule add from 10.20.0.~~2 lookup eth3~~		ip rule add from 10.20.0.215 table webserver_vlan
	</pre>		</pre>

Martin: Created page with "Category:Linux = Source policy routing = If a machine has several interfaces, but only 1 default gateway - it is multihomed and unless the gw supports handling packages w..."

2018-04-12T13:07:19Z

Created page with "Category:Linux = Source policy routing = If a machine has several interfaces, but only 1 default gateway - it is multihomed and unless the gw supports handling packages w..."

New page

[[Category:Linux]]

= Source policy routing =
If a machine has several interfaces, but only 1 default gateway - it is multihomed and unless the gw supports handling packages with 'wrong' source mask, then linux must be told to route packets via the default gw.

== Solution ==
Problem:
Host has 2 interfaces.

eth2: 10.10.0.131/24
eth3: 10.20.0.2/24

eth2 is primary and reponds to ping - eth3 does not.

=== Create new routing table (only needs to be done once) ===
Naming doesn't matter, it just needs to be unique.
A telling name makes sense though.

<pre>
echo 13 eth3 >> /etc/iproute2/rt_tables
</pre>

=== Add a default route to this new table going out eth3 ===
<pre>
ip route add default via 10.20.0.1 table eth3
</pre>

=== Add a policy rule to use this new table for packets with source address of eth3's IP ===
<pre>
ip rule add from 10.20.0.2 lookup eth3
</pre>

=== Lookup new rule ===
<pre>
ip rule show
</pre>

== Source ==
* https://serverfault.com/questions/487891/cant-ping-multihomed-linux-machine-on-non-default-interface

Source policy routing - multihoming - Revision history

Martin at 07:56, 5 July 2019

Martin: Created page with "Category:Linux = Source policy routing = If a machine has several interfaces, but only 1 default gateway - it is multihomed and unless the gw supports handling packages w..."