dnstt

Userspace DNS tunnel RoundTripper based on dnstt by David Fifield. As with David's DNSTT, this repository is all contributed to the public domain.

DNS zone setup

Because the server side of the tunnel acts like an authoritative name server, you need to own a domain name and set up a subdomain for the tunnel. Let's say your domain name is example.com and your server's IP addresses are 203.0.113.2 and 2001:db8::2. Go to your name registrar and add three new records:

A	tns.example.com	points to 203.0.113.2
AAAA	tns.example.com	points to 2001:db8::2
NS	t.example.com	is managed by tns.example.com

The labels tns and t can be anything you want, but the tns label should not be a subdomain of the t label (that space is reserved for the contents of the tunnel), and the t label should be short (because there is limited space available in a DNS message, and the domain name takes up part of that space).

Now, when a recursive DNS resolver receives a query for a name like aaaa.t.example.com, it will forward the query to the tunnel server at 203.0.113.2 or 2001:db8::2.

Tunnel server

Usage

dnstt-server -gen-key [-privkey-file PRIVKEYFILE] [-pubkey-file PUBKEYFILE]
dnstt-server -udp ADDR [-privkey PRIVKEY|-privkey-file PRIVKEYFILE] DOMAIN

Compile the server

dnstt$ cd server
dnstt$ go build -o dnstt-server

Key Generation

First you need to generate the server keypair that will be used to authenticate the server and encrypt the tunnel.

dnstt-server -gen-key -privkey-file server.key -pubkey-file server.pub

Running the Server

You need to provide an address that will listen for UDP DNS packets (:5300), the private key file (server.key), and the root of the DNS zone (t.example.com)

dnstt-server -udp :5300 -privkey-file server.key t.example.com

The tunnel server needs to be able to receive packets on an external port 53. If it is not configured to listen on port 53 directly using -udp :53, it will automatically setup iptables rules to port-forward port 53 to it.