Greetings, If you look at Section 4.1 of the howto, they give asimple example of changing the default route for a single IP address by doing the following # echo 200 John >> /etc/iproute2/rt_tables # ip rule add from 10.0.0.10 table John # ip route add default via 195.96.98.253 dev ppp2 table John # ip route flush cache I''m trying to do something very similar, except that I want to route an entire class C subnet out a different NIC card in my firewall.. I did the exact same thing as above except used the line ip rule add from 192.168.0.1/24 table John ip route add default via 192.168.1.1 dev eth4 table John This doesn''t work, what happens is that the entire subnet loses conect with the firewall, so DNS lookups fail and I basically can''t go anywhere. Using just one IP like the example above seems to work fine.. Any ideas? _______________________________________________ LARTC mailing list / LARTC@mailman.ds9a.nl http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/
Oops, made a mistake in my example, I actually enter ip rule add from 192.168.0.0/24 table John As soon as I do this, that subnet loses all contact with my firewall, so it can''t DHCP an address, do DNS servers, ping, anything.. Any clues? brian@fcu.com <brian@fcu.com> [2003-12-17 22:34:14 -0700]:> Greetings, > > If you look at Section 4.1 of the howto, they give asimple example of changing the default > route for a single IP address by doing the following > > # echo 200 John >> /etc/iproute2/rt_tables > # ip rule add from 10.0.0.10 table John > # ip route add default via 195.96.98.253 dev ppp2 table John > # ip route flush cache > > I''m trying to do something very similar, except that I want to route an entire class C subnet > out a different NIC card in my firewall.. > > I did the exact same thing as above except used the line > > ip rule add from 192.168.0.1/24 table John > ip route add default via 192.168.1.1 dev eth4 table John > > This doesn''t work, what happens is that the entire subnet loses conect with the firewall, so DNS > lookups fail and I basically can''t go anywhere. Using just one IP like the example above seems > to work fine.. > > Any ideas? > > _______________________________________________ > LARTC mailing list / LARTC@mailman.ds9a.nl > http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/_______________________________________________ LARTC mailing list / LARTC@mailman.ds9a.nl http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/
Brian, : Oops, made a mistake in my example, : I actually enter : ip rule add from 192.168.0.0/24 table John : : As soon as I do this, that subnet loses all contact with my firewall, : so it can''t DHCP an address, do DNS servers, ping, anything.. Perhaps what you wish to do is copy the entire main routing table to the table "John" [0] and then change the default route in that table. Try: # copy_routing_table John # ip route change table John default via $OTHER_GATEWAY This is a simple application of policy routing. Another possibility is to exclude 192.168.0.0/24 from the rule itself: # ip rule add from 192.168.0.0/24 table John # ip rule add from 192.168.0.0/24 to 192.168.0.0/24 table main You may wish to consider adding the prio keyword explicitly. See also some documents I have written in which I attempt to explain the policy routing system in plain terms [1]. Good luck, -Martin [0] http://linux-ip.net/html/scripts/copy-routing-table.sh [1] http://linux-ip.net/html/ch-routing.html -- Martin A. Brown --- SecurePipe, Inc. --- mabrown@securepipe.com _______________________________________________ LARTC mailing list / LARTC@mailman.ds9a.nl http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/