Difference between revisions of "Dnsmasq"

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# Google's nameservers, for example
# Google's nameservers, for example

Revision as of 13:15, 29 August 2013


dnsmasq provides services as a DNS cacher and a DHCP server. As a Domain Name Server (DNS), it can cache DNS queries to improve connection speed to previously visited sites. As a DHCP server, dnsmasq can be used to provide internal IP addresses and routes to computers on a LAN. Either or both of these services can be implemented. dnsmasq is considered to be lightweight and easy to configure; it is designed for personal computer use or for use on a network with less than 50 computers. It also comes with a PXE server.


Install dnsmasq from the official repositories.

DNS Cache Setup

To set up dnsmasq as a DNS caching daemon on a single computer edit /etc/dnsmasq.conf and uncomment the localhost listening address:


To use this computer to act as a default DNS specify the fixed IP address of the network:

listen-address=<>  # Example IP

DNS Addresses File

After configuring dnsmasq the DHCP client will need to prepend the localhost address to the known DNS addresses in /etc/resolv.conf. This causes all queries to be sent to dnsmasq before trying to resolve them with an external DNS. After the DHCP client is configured the network will need to be restarted for changes to take effect.


One option is a pure resolv.conf configuration. To do this, just make the first nameserver in /etc/resolv.conf point point to localhost:

# External nameservers

Now DNS queries will be resolved first with dnsmasq, only checking external servers if dnsmasq cannot resolve the query. dhcpcd, unfortunately, tends to overwrite /etc/resolv.conf by default, so if you use DHCP it is a good idea to protect /etc/resolv.conf. To do this, append nohook resolv.conf to the dhcpcd config file:

nohook resolv.conf
More than three nameservers

A limitation the way Linux handles DNS queries is that there can only be a maximum of three nameservers used in resolv.conf. As a workaround, you can make localhost the only nameserver in resolv.conf, and then create a separate resolv-file for your external nameservers. First, create a new resolv file for dnsmasq:

# Google's nameservers, for example

And then edit /etc/dnsmasq.conf to use your new resolv file:



dhcpcd has the ability to prepend or append nameservers to /etc/resolv.conf by creating (or editing) the /etc/resolv.conf.head and /etc/resolv.conf.tail files respectively:

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


For dhclient, uncomment in /etc/dhclient.conf:

prepend domain-name-servers;


NetworkManager has the ability to start dnsmasq from its configuration file. Add the option dns=dnsmasq to NetworkManager.conf in the [main] section then disable dnsmasq from loading as a daemon:


For permanent caching add a config directory for dnsmasq and set the cache number of nameservers (default: 150?):

mkdir /etc/NetworkManager/dnsmasq.d
echo "cache-size=1000" | sudo tee /etc/NetworkManager/dnsmasq.d/cache
Other methods

If using the dnsmasq daemon, then it is necessary to add the localhost address to resolv.conf (which NetworkManager will be overriding).

Since the upgrade of NetworkManager to 0.7, Arch Linux now calls dhcpcd directly instead of the common default with dhclient. Because of the arguments set with dhcpcd, it no longer sources the /etc/resolv.conf.head, and /etc/resolv.conf.tail settings for insertion of name servers. Several options are available.

The first option would be to add a script to the NetworkManager dispatcher to prepend localhost to resolv.conf:

# Prepend localhost to resolv.conf for dnsmasq

if [[ ! $(grep /etc/resolv.conf) ]]; then
  sed -i '1s|^|nameserver\n|' /etc/resolv.conf

and make it executable:

# chmod +x /etc/NetworkManager/dispatcher.d/localhost-prepend

The second option be to go into NetworkManagers' settings (usually by right-clicking the applet) and entering settings manually. Setting up will depending on the type of front-end used; the process usually involves right-clicking on the applet, editing (or creating) a profile, and then choosing DHCP type as 'Automatic (specify addresses).' The DNS addresses will need to be entered and are usually in this form:, DNS-server-one, ....

Lastly, NetworkManager with dhclient can be used (networkmanager-dhclientAUR).

Custom Configuration

As of NetworkManager 0.9.6, custom configurations can be created for dnsmasq by creating configuration files in /etc/NetworkManager/dnsmasq.d/

DHCP Server Setup

By default dnsmasq has the DHCP functionality turned off, if you want to use it you must turn it on in (/etc/dnsmasq.conf). Here are the important settings:

# Only listen to routers' LAN NIC.  Doing so opens up tcp/udp port 53 to
# localhost and udp port 67 to world:

# dnsmasq will open tcp/udp port 53 and udp port 67 to world to help with
# dynamic interfaces (assigning dynamic ips). Dnsmasq will discard world
# requests to them, but the paranoid might like to close them and let the 
# kernel handle them:

# Dynamic range of IPs to make available to LAN pc

# If you’d like to have dnsmasq assign static IPs, bind the LAN computer's
# NIC MAC address:

Start the daemon

To have dnsmasq to load upon startup:

# systemctl enable dnsmasq

To start dnsmasq immediately:

# systemctl start dnsmasq

To see if dnsmasq started properly, check the log; dnsmasq sends its messages to /var/log/messages.log. The network will also need to be restarted so the the DHCP client can create a new /etc/resolv.conf.


DNS Caching

To do a lookup speed test choose a website that has not been visited since dnsmasq has been started (dig is part of the dnsutils package):

$ dig archlinux.org | grep "Query time"

Running the command again will use the cached DNS IP and result in a faster lookup time if dnsmasq is setup correctly.

DHCP Server

From a computer that is connected to the one with dnsmasq on it, configure it to use DHCP for automatic IP address assignment, then attempt to log into the network normally.

Tips and tricks

Prevent OpenDNS Redirecting Google Queries

To prevent OpenDNS from redirecting all Google queries to their own search server, add to /etc/dnsmasq.conf:

server=/www.google.com/<ISP DNS IP>

View leases

$ cat /var/lib/misc/dnsmasq.leases