Automatically set hostname from DHCP in Debian using isc-dhcp-client

One major drawback of isc-dhcp-client in Debian (in this case, Debian 6) is that the option to automatically update the hostname (like dhcpcd) is missing. I came a cross a post on that discusses the problem together with a quite well documented approach on how to fix it. One problem is that, with a decently configured DNS server, the ‘host’ command returns the hostname with a dot at the end.

I updated the script to that it just takes the actual hostname to set it, and by sending a correct domain-name option you will end up with a decent setup (‘hostname’ is the actual, short hostname, ‘hostname –fqdn’ returns the hostname with the domain). Here’s how:

{% highlight bash %}

Filename: /etc/dhcp3/dhclient-exit-hooks.d/hostname

Purpose: Used by dhclient-script to set the hostname of the system

to match the DNS information for the host as provided by


Depends: dhcp3-client (should be in the base install)

hostname (for hostname, again, should be in the base)

bind9-host (for host)

coreutils (for cut and echo)

if [ “$reason” != BOUND ] && [ “$reason” != RENEW ] \
&& [ “$reason” != REBIND ] && [ “$reason” != REBOOT ]

echo dhclient-exit-hooks.d/hostname: Dynamic IP address = $new_ip_address
hostname=$(host $new_ip_address | cut -d ‘ ‘ -f 5 | cut -d ‘.’ -f 1)

echo $hostname > /etc/hostname
hostname $hostname

echo dhclient-exit-hooks.d/hostname: Dynamic Hostname = $hostname

And that should just about do it…

{% endhighlight %}

Thank you!