Difference between revisions of "Dnsmasq"

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[[Category:Networking (English)]]
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[[Category:Domain Name System]]
{{i18n_links_start}}
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[[it:Dnsmasq]]
{{i18n_entry|English|Dnsmasq}}
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[[ru:Dnsmasq]]
{{i18n_entry|Русский|Dnsmasq_(Русский)}}
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[[zh-CN:Dnsmasq]]
{{i18n_links_end}}
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{{Lowercase_title}}
  
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, {{Package Official|dnsmasq}} can be used to provide internal IP addresses to computers on a LAN.  Either or both of these services can be implemented.  Dnsmasq is considered to be lightweight and easy to configure, and is designed for personal computer use or for use on a network with less that 50 computers.
+
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, {{Pkg|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.
  
 
== Installing ==
 
== Installing ==
  
Dnsmasq is in the official repositories and can be installed by:
+
[[pacman|Install]] {{Pkg|dnsmasq}} from the [[Official Repositories|official repositories]].
  
  pacman -S dnsmasq
+
== DNS Cache Setup ==
 +
 
 +
To set up dnsmasq as a DNS caching daemon on a single computer edit {{ic|/etc/dnsmasq.conf}} and uncomment the localhost listening address:
 +
 
 +
  listen-address=127.0.0.1
 +
 
 +
To use this computer to act as a default DNS specify the fixed IP address of the network:
 +
 
 +
listen-address=<192.168.1.1>  # Example IP
 +
 
 +
=== DNS Addresses File ===
 +
 
 +
After configuring dnsmasq the DHCP client will need to prepend the localhost address to the known DNS addresses in {{ic|/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.
 +
 
 +
==== dhcpcd ====
 +
 
 +
{{Pkg|dhcpcd}} has the ability to prepend or append nameservers to {{ic|/etc/resolv.conf}} by creating (or editing) the {{ic|/etc/resolv.conf.head}} and {{ic|/etc/resolv.conf.tail}} files respectively:
 +
 
 +
echo "nameserver 127.0.0.1" > /etc/resolv.conf.head
 +
 
 +
==== dhclient ====
 +
 
 +
For dhclient, uncomment in {{ic|/etc/dhclient.conf}}:
 +
 
 +
prepend domain-name-servers 127.0.0.1;
 +
 
 +
==== NetworkManager ====
 +
 
 +
NetworkManager has the ability to start {{ic|dnsmasq}} from it's configuration file.  Add the {{ic|1=dns=dnsmasq}} option to {{ic|NetworkManager.conf}} in the {{ic|[main]}} section and remove dnsmasq from loading at boot:
 +
 
 +
{{hc|/etc/NetworkManager/NetworkManager.conf|<nowiki>
 +
[main]
 +
plugins=keyfile
 +
dns=dnsmasq
 +
</nowiki>}}
 +
 
 +
Create a NetworkManager dnsmasq config directory if it doesn't exist:
 +
mkdir /etc/NetworkManager/dnsmasq.d
 +
 
 +
===== Other methods =====
 +
 
 +
If using the dnsmasq daemon, then it is necessary to add the localhost address to {{ic|resolv.conf}} (which NetworkManager will be overriding).
 +
 
 +
Since the upgrade of [[NetworkManager]] to 0.7, Arch Linux now calls {{Pkg|dhcpcd}} directly instead of the common default with {{Pkg|dhclient}}.  Because of the arguments set with {{Pkg|dhcpcd}}, it no longer sources the {{ic|/etc/resolv.conf.head}}, and {{ic|/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 {{ic|resolv.conf}}:
 +
 
 +
{{hc|/etc/NetworkManager/dispatcher.d/localhost-prepend|<nowiki>
 +
#!/bin/bash                                     
 +
# Prepend localhost to resolv.conf for dnsmasq
 +
 
 +
if [[ ! $(grep 127.0.0.1 /etc/resolv.conf) ]]; then
 +
  sed -i '1s|^|nameserver 127.0.0.1\n|' /etc/resolv.conf
 +
fi</nowiki>}}
 +
 
 +
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: {{ic|127.0.0.1, DNS-server-one, ...}}.
 +
 
 +
Lastly, NetworkManager with dhclient can be used ({{AUR|networkmanager-dhclient}}).
 +
 
 +
===== Custom Configuration =====
 +
 
 +
As of NetworkManager 0.9.6, custom configurations can be created for dnsmasq by creating configuration files in {{ic|/etc/NetworkManager/dnsmasq.d/}}
  
 
== DHCP Server Setup ==
 
== DHCP Server Setup ==
  
The Dnsmasq configuration file needs to be configured ({{Filename|/etc/dnsmasq.conf}}).  The necessary configurations and their descriptions are as follows:
+
By default dnsmasq has the DHCP functionality turned off, if you want to use it you must turn it on in ({{ic|/etc/dnsmasq.conf}}).  Here are the important settings:
  
<pre>
+
{{bc|<nowiki>
 
# Only listen to routers' LAN NIC.  Doing so opens up tcp/udp port 53 to
 
# Only listen to routers' LAN NIC.  Doing so opens up tcp/udp port 53 to
 
# localhost and udp port 67 to world:
 
# localhost and udp port 67 to world:
Line 34: Line 99:
 
# NIC MAC address:
 
# NIC MAC address:
 
dhcp-host=aa:bb:cc:dd:ee:ff,192.168.111.50
 
dhcp-host=aa:bb:cc:dd:ee:ff,192.168.111.50
</pre>
+
</nowiki>}}
  
If you choose not to bind the interfaces, the domain port will need to be allowed in {{Filename|/etc/hosts.allow}}:
+
== Start the Daemon ==
  
domain ALL : ALLOW
+
To have dnsmasq to load upon startup, add it to the daemons array in {{ic|/etc/rc.conf}}:
  
== DNS Cache Setup ==
+
DAEMONS=(... dnsmasq network ...)
  
If you set up Dnsmasq as a DHCP server, it is already setup to record DNS queries and relay them to an internal network.  To set up dnsmasq as a DNS caching daemon on a personal PC, edit {{Filename|/etc/dnsmasq.conf}} and add the listen address:
+
To stand dnsmasq immediately:
  
  listen-address=127.0.0.1
+
  $ rc.d start dnsmasq
  
After you have configured Dnsmasq, you will need to tell your DHCP client to pre-pend the localhost address to the known DNS addresses file ({{Filename|/etc/resolv.conf}}).  This sends all queries to dnsmasq first before trying to resolve them to an external DNS server.  After your DHCP client is configured, you will need to restart the network for changes to take effect.
+
To see if dnsmasq started properly, check the log; dnsmasq sends its messages to {{ic|/var/log/messages.log}}. The network will also need to be restarted so the the DHCP client can create a new {{ic|/etc/resolv.conf}}.
  
=== dhcpcd ===
+
== Test ==
 +
=== DNS Caching ===
  
{{Package Official|dhcpcd}} has the ability to prepend or append nameservers to {{Filename|/etc/resolv.conf}} by creating (or editing) the {{Filename|/etc/resolv.conf.head}} and {{Filename|/etc/resolv.conf.tail}} files respectively:
+
To do a lookup speed test choose a website that has not been visited since dnsmasq has been started ({{ic|dig}} is part of the {{Pkg|dnsutils}} package):
  
  echo "nameserver 127.0.0.1" > /etc/resolv.conf.head
+
  $ dig archlinux.org | grep "Query time"
  
=== dhclient ===
+
Running the command again will use the cached DNS IP and result in a faster lookup time if dnsmasq is setup correctly.
  
If you use dhclient, add to {{Filename|/etc/dhcp/dhclient.conf}}:
+
=== DHCP Server ===
  
prepend domain-name-servers 127.0.0.1;
+
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.
 
+
==Start the Daemon==
+
 
+
Dnsmasq needs to run as a daemon.  To start it:
+
 
+
/etc/rc.d/dnsmasq start
+
 
+
To have dnsmasq to load upon startup, add dnsmasq to your daemons array in {{Filename|/etc/rc.conf}}:
+
 
+
DAEMONS=(network dnsmasq ...)
+
 
+
To see if dnsmasq started properly, check the log; dnsmasq sends it's messages to {{Filename|/var/log/messages.log}}.
+
 
+
== Test DHCP Server ==
+
 
+
From the LAN client make sure you have the network set up to detect a route with DHCP and attempt to connect to the network.
+
 
+
== Test DNS Caching ==
+
 
+
Do a DNS lookup and measure the time response (dig is part of the {{Package Official|dnsutils}} package):
+
 
+
dig archlinux.org | grep "Query time"
+
 
+
Try it again to compare the result.
+
  
 
== Tips ==
 
== Tips ==
 
Additional tips for Dnsmasq.
 
  
 
=== Prevent OpenDNS Redirecting Google Queries ===
 
=== Prevent OpenDNS Redirecting Google Queries ===
  
To prevent OpenDNS from redirecting all Google queries to their own search server, add to {{Filename|/etc/dnsmasq.conf}}:
+
To prevent OpenDNS from redirecting all Google queries to their own search server, add to {{ic|/etc/dnsmasq.conf}}:
  
  server=/www.google.com/X.X.X.X
+
  server=/www.google.com/<ISP DNS IP>
  
Replace X.X.X.X with your ISP's DNS server/Router IP.
+
=== View leases ===
 +
cat /var/lib/misc/dnsmasq.leases

Revision as of 08:57, 8 November 2012

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.

Installing

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:

listen-address=127.0.0.1

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

listen-address=<192.168.1.1>  # 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.

dhcpcd

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 127.0.0.1" > /etc/resolv.conf.head

dhclient

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

prepend domain-name-servers 127.0.0.1;

NetworkManager

NetworkManager has the ability to start dnsmasq from it's configuration file. Add the dns=dnsmasq option to NetworkManager.conf in the [main] section and remove dnsmasq from loading at boot:

/etc/NetworkManager/NetworkManager.conf
[main]
plugins=keyfile
dns=dnsmasq

Create a NetworkManager dnsmasq config directory if it doesn't exist:

mkdir /etc/NetworkManager/dnsmasq.d
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:

/etc/NetworkManager/dispatcher.d/localhost-prepend
#!/bin/bash                                       
# Prepend localhost to resolv.conf for dnsmasq

if [[ ! $(grep 127.0.0.1 /etc/resolv.conf) ]]; then
  sed -i '1s|^|nameserver 127.0.0.1\n|' /etc/resolv.conf
fi

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: 127.0.0.1, 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:
interface=<LAN-NIC>

# 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:
bind-interfaces

# Dynamic range of IPs to make available to LAN pc
dhcp-range=192.168.111.50,192.168.111.100,12h

# If you’d like to have dnsmasq assign static IPs, bind the LAN computer's
# NIC MAC address:
dhcp-host=aa:bb:cc:dd:ee:ff,192.168.111.50

Start the Daemon

To have dnsmasq to load upon startup, add it to the daemons array in /etc/rc.conf:

DAEMONS=(... dnsmasq network ...)

To stand dnsmasq immediately:

$ rc.d 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.

Test

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

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