I have the same problem in Ubuntu 14.04.3 too...here's my /etc/network/interfaces.
# Localhost auto lo iface lo inet loopback ########################## # WAN - connected to MODEM ########################## # We use allow-hotplug here as otherwise get boot hang if modem down auto eth0 allow-hotplug eth0 iface eth0 inet dhcp The problem comes and goes. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/190359 Title: dhclient continually seeks ip address on unconnected interface To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/dhcp3/+bug/190359/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
