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Are you tired of using 192.168.0.x to refer to the computers within your LAN? Setting up a DNS server and getting domain names for your local computers is surprisingly easy – even on Windows.

0. Preliminary setup: make sure each computer gets a constant IP address

Before setting up the DNS server, you need to ensure that each computer or virtual machine gets a fixed IP address. Otherwise the IP address of the computer may change on each reboot.

This should be done on your router, which is usually located either at 192.168.0.1 or 192.168.1.1 (check your current local IP address by running the Command Prompt and “ipconfig”, which shows your current IP address). Check your router manual on instructions how to log in, most routers have a HTTP-based configuration system which can be accessed when connected to the router.

In my case (I have a Asus RT-N11), the address was 192.168.1.1. Make sure that the computers you want to setup IPs for are connected, then find the “Status” or “DHCP Leases” listing on the router web interface. This listing will contain the MAC addresses for each host. Here is mine:

Host Name       MAC Address       IP Address      Lease
--------------------------------------------------------------
HOST1        00-11-22-33-F0-AC 192.168.1.5     60016 secs.
HOST2        00-11-33-44-F2-2C 192.168.1.6     85074 secs.

A MAC address is a unique identifier given to each network adapter. It allows you to setup fixed IPs.

Find the router functionality which allows you to “Assign IP Addresses Manually”. This should enable you to specify a MAC address and a corresponding fixed IP address. Do this for each of the network adapters you wish to have a fixed IP address. On the Asus RT-N11 this was under “IP Config” -> “DHCP Server”.

Add a MAC address <-> IP address pair for each computer.

1. Get MaraDNS

MaraDNS is a free, lightweight and relatively easy-to-configure DNS server for Windows and Linux. Download it from here and unzip it to some folder.

2. Configure MaraDNS

Open “secret.txt” and change the value to something else (random characters).

The MaraDNS configuration is in the “mararc” file in the same directory. DNS servers have two sets of functionality. They can function as a “Authoritative name server” or a “Recursive/caching name server”.

Authoritative name servers specify IP addresses for domain names. Recursive name servers store information from authoritative name servers and pass on queries in a recursive manner.

We will be configuring both authoritative and recursive functionality in MaraDNS.

2.1 Authoritative configuration

We will configure the server to provide authoritative names of the LAN domain names. Pick any domain, I chose “local.com” (note though that you will not be able to access the actual “local.com” website if you pick an existing domain name).

Add configuration lines to “mararc” like these:

csv2 = {}
csv2["local.com."] = "db.lan.txt"

Where local.com is the domain name you picked, and db.lan.txt is the name of the second configuration file which we will be creating next (change it if you want to name the second configuration file).

Create a new file named “db.lan.txt” in the same directory as MaraDNS.

For each of the computers you want to resolve to a name, add a line to “db.lan.txt”. For example, for two machines, one “dev.local.com” and the other “blog.local.com”, add the following lines:

dev.%       192.168.1.4 ~
blog.%        192.168.1.6 ~

Done!

2.2 Recursive configuration

We will setup MaraDNS to ask your default name servers for all other domains so that you can resolve all other domain names to their correct IP addresses.

Find out your ISP’s DNS server addresses. These are likely to be listed either on the Router status page, or by checking the details on your network adapter.

Now add your ISP’s DNS servers as upstream servers in “mararc”:

upstream_servers = {}
upstream_servers["."] = "xxx.xxx.xxx.xxx, yyy.yyy.yyy.yyy"

Where xxx.xxx.xxx.xxx and yyy.yyy.yyy.yyy are your ISP’s DNS servers.

Done!

3. Run MaraDNS and test it using askmara.exe

Double-click “runmara.bat” , and leave the server running.

Open a command prompt, navigate to the MaraDNS directory and try running:

askmara.exe Agoogle.com.

and

askmara.exe Ablog.local.com.

You should get replies like this:

# Querying the server with the IP 127.0.0.1
# Question: Agoogle.com.
google.com. +300 a 74.125.67.100
google.com. +300 a 74.125.53.100
google.com. +300 a 74.125.45.100
# NS replies:
# AR replies:

and:

# Querying the server with the IP 127.0.0.1
# Question: Ablog.local.com.
blog.local.com. +86400 a 192.168.1.6
# NS replies:
#local.com. +86400 ns synth-ip-7f000001.local.com.
# AR replies:
#synth-ip-7f000001.local.com. +86400 a 127.0.0.1

If you get problems with the first query, you messed up the recursive DNS settings (are your ISP DNS server addresses correct?), and if you get an error with the second query, you messed up the authoritative settings.

4. Change MaraDNS to reply to queries from your LAN

Shutdown the MaraDNS window, and change the first two lines of “mararc” to something like:

ipv4_bind_addresses = "192.168.1.2
recursive_acl = "192.168.1.0/24"

Where 192.168.1.2 is the IP address of the computer on which the server will be running and the “192.168.1″ part of recursive_acl is the same as on your network (might be 192.168.0.0/24).

Start MaraDNS again, and leave it running.

5. Setup your router to hand out your new DNS server

Open your router’s web interface and find the DHCP server settings. There should be an option to set up a DNS server. Write the IP address of the computer on which the DNS server will be running.

For each of your computers, disconnect the network (e.g. by disabling and enabling it in Windows, or by using “ifconfig eth0 down”/”ifconfig eth0 up” on Linux).

That’s it, you should now be able to refer to your LAN computers by their domain names.

This entry was posted on Wednesday, October 14th, 2009 at 12:39 pm and is filed under How-to, Technology. You can follow any comments to this entry through the RSS 2.0 feed. You can leave a comment, or trackback from your own site.