LinuxQuestions.org - dhclient not setting default gateway

I administer a 12-computer network, running Fedora Core 3 with

Code:

[root@uma ~]# uname -a

Linux uma 2.6.9-1.667 #1 Tue Nov 2 14:41:25 EST 2004 i686 i686 i386 GNU/Linux

I perform regular updates from the freshrpms apt repository (in fact, I use a UK mirror). Recently, one of the computers on our network refused to connect to the WAN after a restart. I later replicated the problem on another computer which *was* connected to the WAN, simply by reloading the network configuration with "/etc/init.d/network reload" - after which there was no connection to the WAN. I can then ping 127.0.0.1, and the IP address of the local machine, and other machines on the LAN, but not further - not even the gateway on our network segment.

I believe the problem is due to the script dhclient-script, and I have been unable to find a solution to this problem on the web. Please forgive me if this problem has already been resolved.

I believe that dhclient-script is failing to set the default gateway, since on the affected machines we have

Code:

[root@uma ~]# route

Kernel IP routing table

Destination    Gateway        Genmask        Flags Metric Ref    Use Iface

10.10.41.0      *              255.255.255.0  U    0      0        0 eth0

169.254.0.0    *              255.255.0.0    U    0      0        0 eth0

despite the fact that eth0 is configured by DHCP:

Code:

[root@uma ~]# grep -v ^# /etc/sysconfig/network-scripts/ifcfg-eth0

DEVICE=eth0

BOOTPROTO=dhcp

HWADDR=00:A0:C9:E6:C3:A8

ONBOOT=yes

TYPE=Ethernet

and the lease received from the server includes the option "routers"

Code:

[root@uma ~]# tail -n 15 /var/lib/dhcp/dhclient-eth0.leases

lease {

  interface "eth0";

  fixed-address 10.10.41.8;

  option subnet-mask 255.255.255.0;

  option routers 10.10.41.254;

  option dhcp-lease-time 1800;

  option dhcp-message-type 5;

  option domain-name-servers 10.10.1.253;

  option dhcp-server-identifier 10.1.1.1;

  option broadcast-address 10.10.41.255;

  option domain-name "physics.nat";

  renew 3 2005/3/9 15:17:30;

  rebind 3 2005/3/9 15:29:56;

  expire 3 2005/3/9 15:33:41;

}

I was further lead to believe that the fault is in dhclient when I looked at the timestamps on the dhclient scripts:

Code:

[root@uma ~]# ls -l /sbin/dhclient*

-rwxr-xr-x  1 root root 356004 Feb 25 02:05 /sbin/dhclient

-rwxr-xr-x  1 root root  12384 Feb 25 02:05 /sbin/dhclient-script

So the change happened some time after Feb 25 - and I certainly didn't do it, since I don't tamper with system scripts. I then looked through my upgrade logs, and found the following updates since 24/2/2005:

24/2/2005 - postgresql-libs
27/2/2005 - at bind bind-libs bind-utils dhclient firefox gaim pvm tcsh vixie-cron
4/3/2005 - gamin gamin-devel
5/3/2005 - tzdata
6/3/2005 - firefox libtool libtool-libs
9/3/2005 - gaim

Circumstantial evidence is building against dhclient, since we now know it had "opportunity" and "means". I then copied dhclient-script from a machine running Fedora Core 1 to uma, with timestamps from *before* 25/2/2005:

Code:

[robert@kingsley: robert] ls -l /sbin/dhclient*

-rwxr-xr-x  1 root root 350000 Oct  8  2003 /sbin/dhclient

-rwxr-xr-x  1 root root  8181 Oct  8  2003 /sbin/dhclient-script

and everything worked fine! The default gw was included in the routing table, and the WAN was visible!

I have cursorily glanced at what has changed in dhclient-script, but do not yet have a solution (what we might fancifully call the "motive", building on the Columbo metaphor from earlier). I suspect this behaviour may even be intentional, to comply with behaviour of other systems. But, it does not seem particularly helpful behaviour to me. And I believe other people have recently been having the same problem:

thread 293615
thread 298569
thread 296513
thread 299378

Any thoughts? Is anyone having the same problem? It looks suspiciously like a bug to me.

Thanks,
Robert.