vahempio/dns-ipy repository overview

⁠DNS-IPy

https://github.com/vahempio/dns-ipy⁠

https://hub.docker.com/r/vahempio/dns-ipy⁠

MIT license

⁠Short brief

This is a tiny DNS demonstrator to dynamicaly respond from a A query to an IP address.

Usage example:

$ python3 ./dns-ipy.py &
$ nslookup -port=5053 1-2-3-4.foo.bar 127.0.0.1

And the answer will be: 1.2.3.4

⁠Long brief

This DNSserver will parse your A request, and create an answer with the IP address contained inside the request. This is the process used by Plesk to convert an URL into a local IP: useful to use a valid https certificate on a local server.

The valid format of the request is the following:

• A-B-C-D.subdomain.domain.tld (where A,B,C,D are [0:255] digits of the IPv4 address)
• request type A The answer will be: A.B.C.D

Launch the python script to start a DNSserver on the 5053 port (UDP+TCP) and query the server with:

$ nslookup -port=5053 -type=A 1-2-3-4.foo.bar 127.0.0.1
Server:		127.0.0.1
Address:	127.0.0.1#5053

Name:	1-2-3-4.foo.bar
Address: 1.2.3.4

⁠Docker

Start with:

docker run -it -p 5053:5053/udp vahempio/dns-ipy

⁠Docker-compose

docker-compose.yml example:

version: "2"

services:
  dns-ipy:
    image: vahempio/dns-ipy
    restart: on-failure
    ports:
      - "53:5053/tcp"
      - "53:5053/udp"

    # For logs:
    stdin_open: true
    tty: true

⁠Use it on the field

The example scenario supposes that you have a domain name (we use foo.bar here) and your own server (like a VPS) with a A record like vps.foo.bar.

• Deploy the container on your server, by copying the docker-compose.yml and start it with docker-compose up -d.
• On your computer, try the resolution by forcing the address of the server: nslookup 1-2-3-4.foo.bar vps.foo.bar. Result should be 1.2.3.4.
• Create a CNAME entry in your DNS records like ns.foo.bar IN CNAME vps.foo.bar. to have a clean situation.
• Create a NS entry in your DNS records like hash.foo.bar IN NS ns.foo.bar. to delegate the subzone to your server.
• Enjoy and test it, with nslookup 1-2-3-4.youruid.hash.foo.bar. Result should be 1.2.3.4.

Now, you can create a https wildcard for the domain *.youruid.hash.foo.bar with a challenge/response through DNS with Let's Encrypt, for example. With it, your local server can have a verified https certificate with a local IP only, and this DNS-IPy will route to your local IP address.