How to start dhclient at boot?

Question

Here's the problem:

root@home:~# ping 8.8.8.8
connect: Network is unreachable

root@home:~# dhclient eth0
RTNETLINK answers: File exists

root@home:~# ping 8.8.8.8 
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
64 bytes from 8.8.8.8: icmp_req=1 ttl=51 time=16.8 ms
64 bytes from 8.8.8.8: icmp_req=2 ttl=51 time=16.6 ms
^C
--- 8.8.8.8 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1002ms
rtt min/avg/max/mdev = 16.654/16.737/16.820/0.083 ms
root@home:~#

Network is working only after I manually invoke dhclient. I don't have NetworkManager (removed it). Here are relevant lines from /etc/network/interfaces:

auto eth0
iface eth0 inet dhcp

And here is startup log:

root@home:~# cat /var/log/syslog | grep dhclient
May 28 21:39:44 home kernel: [    7.237076] type=1400 audit(1369762781.497:2): apparmor="STATUS" operation="profile_load" name="/sbin/dhclient" pid=405 comm="apparmor_parser"
May 28 21:39:44 home kernel: [    7.238298] type=1400 audit(1369762781.497:4): apparmor="STATUS" operation="profile_load" name="/usr/lib/connman/scripts/dhclient-script" pid=405 comm="apparmor_parser"
May 28 21:39:45 home dhclient: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 8 (xid=0x79607e29)
May 28 21:39:45 home dhclient: DHCPREQUEST of 192.168.0.103 on eth0 to 255.255.255.255 port 67 (xid=0x79607e29)
May 28 21:39:45 home dhclient: DHCPOFFER of 192.168.0.103 from 192.168.0.1
May 28 21:39:45 home dhclient: DHCPACK of 192.168.0.103 from 192.168.0.1
May 28 21:39:45 home dhclient: bound to 192.168.0.103 -- renewal in 234779 seconds.
May 28 21:39:45 home kernel: [   11.695666] type=1400 audit(1369762785.953:10): apparmor="STATUS" operation="profile_replace" name="/sbin/dhclient" pid=1154 comm="apparmor_parser"
May 28 21:40:11 home dhclient: DHCPREQUEST of 192.168.0.103 on eth0 to 255.255.255.255 port 67 (xid=0x2aa61c47)
May 28 21:40:11 home dhclient: DHCPACK of 192.168.0.103 from 192.168.0.1
May 28 21:40:11 home dhclient: bound to 192.168.0.103 -- renewal in 243414 seconds.

Any ideas what may cause such problem?

Solution

As it seems its because the /var/lib/dhcp3 or /var/run has not yet been mounted when the DHCP client is started.

According to the ManPage of dhclient, try to specify the names and/or locations for these files, use the -cf, -lf, -pf and -sf flags, respectively,followed by the name of the file. (The DHCP client normally gets its configuration information from

  /etc/dhcp3/dhclient.conf

,its lease database from

  /var/lib/dhcp3/dhclient.leases

, stores its process ID in a file called

   /var/run/dhclient.pid 

and configures the network interface using

   /sbin/dhclient-script

Comments

[Artemis]

please check if it help; askubuntu.com/questions/407398/…

[solsTiCe]

From the log, everything seems ok.