Stop dhclient from adding a default gateway

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

Hello,

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.

I set up a definition for each interface in dhclient.conf and explicitly 
requested everything except "routers".  Here's an example using the 
interface for VLAN 52:

interface "vlan52" {
  request subnet-mask, broadcast-address, time-offset, domain-name, 
domain-name-servers, host-name;
}

I deleted everything else from the config file, so it's literally just 
one big list of interface definitions like the one above.  I also set up 
two shell scripts per VLAN, one to set up a static route and the other 
to delete the route, and set these scripts to run as post-up/pre-down 
commands for the respective VLAN interface in /etc/network/interfaces, 
like so:

# VLAN 52 - Library
iface vlan52 inet dhcp
        vlan_raw_device eth1
        post-up /etc/network/scripts/vlan52_add_route
        pre-down /etc/network/scripts/vlan52_del_route

The scripts work and I get the static route, but I still get a default 
route as well:

# ifup vlan52
Set name-type for VLAN subsystem. Should be visible in /proc/net/vlan/config
Added VLAN with VID == 52 to IF -:eth1:-
Internet Systems Consortium DHCP Client V3.1.2
Copyright 2004-2008 Internet Systems Consortium.
All rights reserved.
For info, please visit http://www.isc.org/sw/dhcp/

Listening on LPF/vlan52/00:0d:56:f0:33:5c
Sending on   LPF/vlan52/00:0d:56:f0:33:5c
Sending on   Socket/fallback
DHCPDISCOVER on vlan52 to 255.255.255.255 port 67 interval 5
DHCPOFFER of 10.5.2.176 from 10.5.2.1
DHCPREQUEST of 10.5.2.176 on vlan52 to 255.255.255.255 port 67
DHCPACK of 10.5.2.176 from 10.5.2.1
bound to 10.5.2.176 -- renewal in 107356 seconds.

# netstat -rn
Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt 
Iface
10.5.2.0        10.5.2.1        255.255.255.0   UG        0 0          0 
vlan52 <-- STATIC ROUTE SET BY THE POST-UP SCRIPT
10.5.2.0        0.0.0.0         255.255.255.0   U         0 0          0 
vlan52 <-- DEFAULT ROUTE ADDED BY DHCP!
10.3.0.0        0.0.0.0         255.255.248.0   U         0 0          0 
eth0
0.0.0.0         10.3.1.1        0.0.0.0         UG        0 0          0 
eth0

Any help would be greatly appreciated.

    Thanks!
    Dave

--

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