Dnsmasq - a DNS forwarder for NAT firewalls.

# Dnsmasq

Dnsmasq is a 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 diskless machines.

Dnsmasq is targeted at home networks using NAT and connected to the internet via a modem, cable-modem or ADSL connection but would be a good choice for any small network where low resource use and ease of configuration are important.

Supported platforms include Linux (with glibc and uclibc), *BSD and Mac OS X. Dnsmasq is included in at least the following Linux distributions: Gentoo, Debian, Slackware, Suse, Smoothwall, IP-Cop, floppyfw, Firebox, LEAF, Freesco, fli4l, CoyoteLinux, Endian Firewall and Clarkconnect. It is also available as a FreeBSD port and is used in Linksys wireless routers and the m0n0wall project.

Dnsmasq provides the following features:

- The DNS configuration of machines behind the firewall is simple and doesn't depend on the details of the ISP's dns servers
- Clients which try to do DNS lookups while a modem link to the internet is down will time out immediately.
- Dnsmasq will serve names from the /etc/hosts file on the firewall machine: If the names of local machines are there, then they can all be addressed without having to maintain /etc/hosts on each machine.
- The integrated DHCP server supports static and dynamic DHCP leases and multiple networks and IP ranges. It works across BOOTP relays and supports DHCP options including RFC3397 DNS search lists. Machines which are configured by DHCP have their names automatically included in the DNS and the names can specified by each machine or centrally by associating a name with a MAC address in the dnsmasq config file.
- Dnsmasq caches internet addresses (A records and AAAA records) and address-to-name mappings (PTR records), reducing the load on upstream servers and improving performance (especially on modem connections).
- Dnsmasq can be configured to automatically pick up the addresses of it's upstream nameservers from ppp or dhcp configuration. It will automatically reload this information if it changes. This facility will be of particular interest to maintainers of Linux firewall distributions since it allows dns configuration to be made automatic.
- On IPv6-enabled boxes, dnsmasq can both talk to upstream servers via IPv6 and offer DNS service via IPv6. On dual-stack (IPv4 and IPv6) boxes it talks both protocols and can even act as IPv6-to-IPv4 or IPv4-to-IPv6 forwarder.
- Dnsmasq can be configured to send queries for certain domains to upstream servers handling only those domains. This makes integration with private DNS systems easy.
- Dnsmasq supports MX records and can be configured to return MX records for any or all local machines.

## Download.

Download dnsmasq here. The tarball includes this documentation, source, manpage and control files for building .rpms. There are also pre-built i386 .rpms, and a CHANGELOG. Dnsmasq is part of the Debian distribution, it can be downloaded from here or installed using `apt`.

## Building rpms.

Assuming you have the relevant tools installed, you can rebuild .rpms simply by running (as root)

    rpmbuild -ta dnsmasq-xxx.tar.gz

Note for Suse users: you will need to re-compress the tar file as bzip2 before building using the commands

    gunzip dnsmasq-xxx.tar.gz
    bzip2 dnsmasq-zzz.tar

## Links.

There is an article in German on dnsmasq at http://www.linuxnetmag.com/de/issue7/m7dnsmasq1.html and Damien Raude-Morvan has one in French at http://www.drazzib.com/docs-dnsmasq.html There is a good article about dnsmasq at http://www.enterprisenetworkingplanet.com/netos/article.php/3377351 and Ilya Evseev has an article in Russian about dnsmasq to be found at http://ilya-evseev.narod.ru/articles/dnsmasq

## License.

Dnsmasq is distributed under the GPL. See the file COPYING in the distribution for details.

## Contact.

There is a dnsmasq mailing list at http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss which should be the first location for queries, bugreports, suggestions etc. Dnsmasq was written by Simon Kelley. You can contact me at simon@thekelleys.org.uk.