Comment 0 for bug 1447715

Eloy Paris (peloy-chapus) wrote :

After upgrading to Ubuntu 15.04 my computer is unable to obtain an IPv6 address via DHCPv6. The root cause is that dhclient is exiting with the following message:

Can't bind to dhcp address: Cannot assign requested address
Please make sure there is no other dhcp server
running and that there's no entry for dhcp or
bootp in /etc/inetd.conf. Also make sure you
are not running HP JetAdmin software, which
includes a bootp server.

If you think you have received this message due to a bug rather
than a configuration issue please read the section on submitting
bugs on either our web page at or in the README file
before submitting a bug. These pages explain the proper
process and the information we find helpful for debugging..


The problem seems to exist in isc-dhcp-client 4.3.1-5ubuntu2 (15.04 version) because downgrading to isc-dhcp-client 4.2.4-7ubuntu14 (14.10 version) allows me to obtain an address.

NetworkManager is the one launching dhclient. The two invocations (one for IPv4 and one for IPv6) are:

dhclient_start(): running: /sbin/dhclient -d -q -sf /usr/lib/NetworkManager/nm-dhcp-helper -pf /run/sendsigs.omit.d/ -lf /var/lib/NetworkManager/ -cf /var/lib/NetworkManager/dhclient-eth0.conf eth0

dhclient_start(): running: /sbin/dhclient -d -q -6 -N -sf /usr/lib/NetworkManager/nm-dhcp-helper -pf /run/sendsigs.omit.d/ -lf /var/lib/NetworkManager/ -cf /var/lib/NetworkManager/dhclient6-eth0.conf eth0

I do not see anything suspicious with the way both dhclients are invoked.

Given that a downgrade allows me to obtain an IPv6 address I think this might be a bug in the ISC DHCP client rather than in NetworkManager.