[[!meta title="Setting static nameserver and search path with dhcpcd"]]

If you're changing networks a lot, but want to keep a some static
settings, this is **one** way to do it.

## Motivation

As most wireless networks are featured with unreliable and slow connections,
I'm running my own (caching only) dns server on my notebook, to keep the
answers in my local cache. Thus I always want to have

    nameserver 127.0.0.1

as the first entry in my ***resolv.conf***.

Additionally, I always want to have **schottelius.org** and **ethz.ch**
in my search path, resulting in

    search schottelius.org ethz.ch

Thus I am always able to type only the hostname, independent of my location.

## Implementation

I am currently using [dhcpcd](http://roy.marples.name/projects/dhcpcd/),
which is shipped with [archlinux](http://www.archlinux.org/) by default.

The package contains **/usr/lib/dhcpcd/dhcpcd-hooks/20-resolv.conf**,
which takes ***/etc/resolv.conf.head*** and ***/etc/resolv.conf.tail***
into account.

According to **resolv.conf(5)**, if multiple nameservers are specified,
they will be asked in the order listed, so 

    echo nameserver 127.0.0.1 > /etc/resolv.conf.head

ensures that my local nameserver is asked firstly. As the **domain** and
**search** field override each other, the last entry wins:

    echo search schottelius.org ethz.ch > /etc/resolv.conf.tail

## Further information

The same can easily be done with other modular dhcp-clients, like udhcpc
(part of [busybox](http://www.busybox.net/)).

The behaviour of your resolver library may be different, be sure to
check your local system documentation.

There are a lot of small caching nameservers available. I have good
experiences with [dnscache](http://cr.yp.to/djbdns/dnscache.html),
[dnsmasq](http://www.thekelleys.org.uk/dnsmasq/) and
[unbound](http://www.unbound.net/).

[[!tag net sysadmin unix]]