Re: Stop dhclient from adding a default gateway

["David A. Parker" <dparker@utica.edu>]

On 09/03/2010 02:09 PM, Bob Proulx wrote:
> David A. Parker wrote:
> > I have a Debian Lenny box with two NICs, eth0 and eth1. eht1 is a
> > trunking interface and can be put onto any VLAN.  Whenever eth1 is
> > put onto a VLAN, I want it to get an address from DHCP but I do
> > *not* want it to set a default gateway.
> > ...
> > Any help would be greatly appreciated.
>
> By coincidence I have been hacking on these scripts today too...
>
> The dhclient-script sets the route.  If you want to prevent it then
> you will have to either prevent dhclient-script from setting it or to
> remove it after it has been set.

Thanks, Bob.  I had looked at dhclient-script and realized that it was 
the culprit, but I was hoping to avoid hacking up that script.  I tried 
adding a line to my post-up script to remove the default route, like so:

route del -net 10.5.2.0/24 gw 0.0.0.0 dev vlan52

But this removes the static route instead!  I don't know why it's 
behaving like that.

It appears that I can delete both routes, but only in a certain order. 
I can only delete the default route once the static route is gone.  And 
if I don't have any routes for that network, "route" won't let me add 
the static route unless a default route is already there.  I have to add 
the default route first, and then I can add the static one.  So, if I 
stop dhclient from adding the default route, it seems like this would 
prevent my post-up script from being able to add the static route.

I'm very confused by this.  Does the kernel absolutely require a default 
route for every network the host is on?  Because that's exactly what I'm 
trying to avoid.

    Thanks,
    Dave

--

Dave Parker
Systems Administrator
Utica College
Integrated Information Technology Services
(315) 792-3229
Registered Linux User #408177