Dnsmasq is lightweight, easy to configure DNS forwarder and DHCP server. It is designed to provide DNS and, optionally, DHCP, to a small network. It can serve the names of local machines which are not in the global DNS. The DHCP server integrates with the DNS server and allows machines with DHCP-allocated addresses to appear in the DNS with names configured either in each host or in a central configuration file. Dnsmasq supports static and dynamic DHCP leases and BOOTP for network booting of disk-less machines.
It is already installed and preconfigured on OpenWrt. See → /etc/config/dhcp.
The configuration is done with help of the uci-configuration file: /etc/config/dhcp, but you can use this together with the file
Depending on the setting in the uci-file, you may also use the files
You can use
/etc/dnsmasq.conf in addition, see above.
Example: By default, dnsmasq comes configured to put your hosts into the
.lan domain. This is specified in the configuration file as:
# allow /etc/hosts and dhcp lookups via *.lan
You can change this to whatever you’d like your home domain to be. Also, if you want your hosts to be available via your home domain without having to specify the domain in your
file, add the
expand-hosts directive to your
As an example, without
expand-hosts, you can only reach router, ubuntu-desktop and ubuntu-laptop. With expand-hosts on, you can reach router, router.lan, ubuntu-desktop, ubuntu-desktop.lan, etc. This probably matches what you’re looking for anyway.
Without this setting, you’ll have to add .lan entries to your
/etc/ethers static lease entries can be assigned. See → static_leases.
/etc/hosts DNS entries are configured. dnsmasq will utilize these entries to answer DNS queries on your network.
[IP_address] host_name host_name_short ...
192.168.1.1 router OpenWrt localhost
DNS needs TCP and UDP port 53 open on the firewall. DHCP needs UDP ports 67 and 68 open from your zone to/from the firewall. See http://wiki.openwrt.org/doc/recipes/guest-wlan and http://www.thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html (viz “–dhcp-alternate-port”) for more information.
What to do if you already have a DNS server(secondary DNS server) but you want your router(primary DNS server) to resolve some of the DNS queries? Simply do the following:
That will remove the resolv.conf symlink. Then we will add the ip address of the secondary DNS inside the /etc/resolv.conf file
echo "nameserver 192.168.1.2"> resolv.conf
Replace 192.168.1.2 by the ip of your dns server then reboot or restart the dnsmasq service.
Then you’ll need to set up your secondary dns for resolving internet’s DNS queries: ssh into your router then:
it will give you something like this:
Copy the information and then add it to your secondary DNS’s /etc/resolv.conf: into your secondary dns do:
echo "nameserver 22.214.171.124">> resolv.conf
echo "nameserver 126.96.36.199">> resolv.conf
Replace 188.8.131.52 and 184.108.40.206 with the IP addresses you have gotten with the cat /tmp/resolv.conf.auto command.
Just add the following lines to /etc/dnsmasq.conf to use Google Public DNS.
In case you prefer to use OpenWrt UCI, you may issue the following commands.
uci add_list dhcp.@dnsmasq[-1].server=220.127.116.11
uci add_list dhcp.@dnsmasq[-1].server=18.104.22.168
uci commit dhcp
You may also edit /etc/config/dhcp directly.
In case you want to use OpenDNS (there are 4 public dns servers)
uci add_list dhcp.@dnsmasq[-1].server=22.214.171.124
Of course, you can use another dns servers. Just send a SIGHUP to dnsmasq process or restart dnsmasq service to apply the newly added forwarding DNS servers.
Suppose you have the following:
vlan0 Link encap:Ethernet HWaddr XX:XX:XX:XX:XX:XX
Simply put 2 “dhcp-range” options in your
You can then use the different “network-id” values with “dhcp-option” to customize the options your DHCP server will supply to your wired and wireless DHCP clients.
set the default route for dhcp clients on the wlan side to 10.10.6.33
There are situations where you want dnsmasq to generate DHCP addresses for only known clients (as defined in
/etc/ethers). First, set
lan_dhcp_num=0 to indicate that no addresses are to be generated. Then, modify the file
`/etc/init.d/S60dnsmasq` to included the lines
after the calls to
ipcalc.sh . Restart the daemon or reboot.
You will need the following lines in your
/etc/dnsmasq.conf file: (Adjust IP address if your router is not 192.168.1.1)
That’s it for dnsmasq on the router. The trick is that the DHCP client must send its hostname during the DHCP negotiation. The
dhclient.conf file, which may be in
/etc/ (debian) or
/etc/dhcp3/ (kubuntu), needs to have a single line uncommented and edited:
send host-name "hostname";
Save the file, then restart the interface. Repeat on all client systems.
You will need the following line in your
/etc/dnsmasq.conf file: (Adjust IP address if your WINS server is not 192.168.1.2)
Now as your machines release and renew DHCP information they will obtain the address of the WINS server automatically.
The following change to your
/etc/dnsmasq.conf file will allow for automatic configuration of your DHCP clients to use DNS servers other than one on the router.
Or you can do the same in
As your machines release and renew their DHCP configuration they will obtain the address of the new DNS servers automatically.
By default, the option filterwin2k in dnsmasq is activated, which seems to cause to block queries for
SRV records are not only used by Windows computers to find their domaincontrollers but also used by e.g SIP-Phones to find the server responsible for a given domain.
SRV records are a kind of generalized
filterwin2k option needs to be disabled in order to let SIP-Phones work that use dnsmasq as their DNS server.
Commented out in
/etc/dnsmasq.conf or de-activate it in the web-interface.
Or you can do the same in
Windows 7 among others ask for proxy settings using DHCP. The issue is that they do not stop asking until they have received an answer. This results in that the log contains a lot information about these requests, an example can be found below (thanks for http://wiki.excito.org for the info).
Jul 1 06:34:09 MorganB3 dnsmasq-dhcp: DHCPINFORM(br0) 10.69.10.59 00:23:14:c5:33:fc
Jul 1 06:34:09 MorganB3 dnsmasq-dhcp: DHCPACK(br0) 10.69.10.59 00:23:14:c5:33:fc MorgansVaioF12Z
To solve this, edit /etc/dnsmasq.conf and add the following lines:
and restart dnsmasq with /etc/init.d/dnsmasq restart
The queryport is not the dns server port used by dhcp clients, it is the outgoing port dnsmasq uses to query other servers, and is integral to dnsmasq succesfully assigning DNS values to the DHCP clients. The default settings create arbitrary high port number connections on a range of ports. By assigning an option line like “ option queryport ‘30000’ “ in /etc/config/dhcp, one can constrain those connections to a port you assign. Be certain that your firewall allows outbound connections from the router on the query port that you assign.
As a caution, dnsmasq runs as user “nobody” on openwrt so it is not allowed to create listening sockets on ports < 1024. Using the standard DNS port 53 for these queries will fail. The failure can be found in the logs. Logread will show an “ignoring nameserver” error line like:
Jan 01 01:01:01 MyRoutersName daemon.warn dnsmasq: ignoring nameserver 126.96.36.199 - cannot make/bind socket: Permission denied
Do not assign query ports less than 1024 to the queryport.
Project Homepage: http://thekelleys.org.uk/dnsmasq/doc.html
The Why·Liam·Blog by WhyLiam is licensed under a Creative Commons BY-NC-ND 4.0 International License.