deno-nameserver is a DNS Server written using Deno

This is a very basic experiment at writing a simple DNS server using Deno, using the currently-unstable UDP datagram support in Deno (i.e. you have to run with --unstable). Vaguely following RFC1035, but mostly implemented by looking at Wireshark captures. Does not support TCP, so messages need to fit within a single UDP packet.

It is intended to act as a local server to respond to basic queries, and does not offer recursive lookups.

Obviously this is not stable and not for production use! It seems like dig et al though seem to be happy enough with the responses it sends.

Usage

Update the content of config.ts as required (see below), then run it:

deno run --unstable --allow-net main.ts

Configuring the server via config.ts

IP & PORT

Typically you'll want to leave these alone and keep them at their defaults of 0.0.0.0 and 53 - this will make the server listen on all IPs at the usual port for DNS servers.

NAMES

This is where you configure the names you want to respond to.

In this example there are two names that the server is configured to respond to.

  public static readonly NAMES:DNSConfig = {
    'MyNas.whatever': {
      ttl: 3600,
      class: {
        'IN': {
          'A': '192.168.0.17',
        }
      }
    },
    'HomePrinter.something.cool': {
      ttl: 3600,
      class: {
        'IN': {
          'A': '192.168.0.123',
        }
      }
    },
  };

Add as many records as you need. Typically you'll want them all to be IN class (i.e. internet) and A record types (i.e. IPv4 address). Note that your OS or router's DHCP settings might automatically append a suffix to any name you try to lookup - either disable that, or add an entry with the suffix if you want to serve those names.

Since the config is actually included as a typesccript module, you can do cunning stuff in the config.ts file if you really want to, such as dynamic names or addresses. As far as I am aware (and I have done zero research here) this is something fairly unique among DNS servers. The flip side is that it has absolutely zero fault tolerance since it needs to be compiled as it is actually typescript code.

Why? Why don't you use dnsmasq or whatever?

This was just written for the fun of it. I needed a simple DNS server for use with tailscale and I thought it would be more fun to write my own than read the docs for dnsmasq.