Hook to prevent dhclient to update resolv.conf

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I ran into an issue where I had a server with two static IP interface and one dynamic. The setup required the system to have a specific DNS setup in resolv.conf, but the dynamic interface was overriding it every time it got a new lease.

Create the hook

dhclient supports scripts that will run when it starts and when it exits.

We need a script that will run on entering hooks so we will create the file in this directory.

vim /etc/dhcp3/dhclient-enter-hooks.d/nodnsupdate

Add the following code:

#!/bin/sh
make_resolv_conf(){
    :
}

And make it executable:

chmod +x /etc/dhcp3/dhclient-enter-hooks.d/nodnsupdate