dhclient3 tries to access nonexistent /var/lib/dhcp3 for lease file

[Tuomas Heino]

According to ps dhclient3 tries to store leases in /var/lib/dhcp3, but only /var/lib/dhcp exists on natty:

root 676 0.0 0.0 7080 980 ? Ss May30 0:03 dhclient3 -e IF_METRIC=100 -pf /var/run/dhclient.eth0.pid -lf /var/lib/dhcp3/dhclient.eth0.leases eth0
$ ls -ld /var/lib/dhcp*
drwxr-xr-x 2 root root 4096 2011-05-30 00:29 /var/lib/dhcp

That might cause unnecessary IP changes in some scenarios, but haven't witnessed any ill effects myself yet.

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: isc-dhcp-client 4.1.1-P1-15ubuntu9
ProcVersionSignature: Ubuntu 2.6.38-8.42-server 2.6.38.2
Uname: Linux 2.6.38-8-server x86_64
Architecture: amd64
Date: Sat Jun 18 15:16:00 2011
DhclientLeases:

ExecutablePath: /sbin/dhclient
InstallationMedia: Ubuntu-Server 11.04 "Natty Narwhal" - Release amd64 (20110426)
KernLog:

ProcAttrCurrent: /sbin/dhclient (enforce)
ProcCmdLine: BOOT_IMAGE=/vmlinuz-2.6.38-8-server root=/dev/mapper/hostname-root ro quiet
ProcEnviron: PATH=(custom, no user)
ProcVersionSignature_: Ubuntu 2.6.38-8.42-server 2.6.38.2
SourcePackage: isc-dhcp
UpgradeStatus: No upgrade log present (probably fresh install)

[Tuomas Heino (iheino+ub)]

From description of Bug #768171

"""
I think it is wrong that isc-dhcp-client version four is providing a dhclient3 file.

It is a problem because ifupdown first checks for dhclient3 and runs that, using a lease directory option of /var/lib/dhcp3. This is a problem if you remove dhcp3 directories.
"""

In clean-install case the dhcp3 directories never existed to begin with.
Removing the apparently unnecessary /sbin/dhclient3 symlink does indeed fix this issue, as suggested by the quoted comment above.

[Kenyon Ralph (kralph)]

Quoting the original report: "That might cause unnecessary IP changes in some scenarios, but haven't witnessed any ill effects myself yet."

I have witnessed ill effects. In my case, my ISP's dhcp server provides an incorrect dhcp-server-identifier to clients, so I do this in my dhclient.conf to fix it:
  supersede dhcp-server-identifier 10.124.192.1;

But, this does not take effect if dhclient cannot save a leases file, which is the case when the /sbin/dhclient3 symlink exists.