Re: [LARTC] Changing default route for an entire subnet/NIC

["Martin A. Brown" <mabrown-lartc@securepipe.com>]

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

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