Whoami DNS

whoami-dns is a clever webserver that runs the backend for https://debug.charliejonas.co.uk/dns.html. It's designed to work in tandem with an authoritative DNS server using dnstap and wildcard domains so that clients' recursive DNS servers can be identified by the source IP addresses of their queries.

Principle

1. A zonefile contains a * 1 A 192.0.2.1 wildcard record where 192.0.2.1 is the public IP address of the host.
2. The name server that is authoritative for that zone is configured to use dnstap via a UNIX socket.
3. whoami-dns listens on that socket and detects incoming DNS queries.
4. The source IP address and domain of the query are parsed and stored by whoami-dns.
5. whoami-dns listens for incoming HTTP requests and uses the Host header to determine the source IP address of the DNS query.
6. A plaintext HTTP response body is sent by whoami-dns containing the client's recursive resolver's IP address.

Usage

Usage:
  whoami-dns [flags]

Flags:
  -b, --bind string   path to dnstap UNIX socket (default "/var/lib/knot/dnstap.sock")
  -h, --help          help for whoami-dns
  -p, --port string   port on which to listen for HTTP requests (default "6780")

Installation

Pre-built binaries for a variety of operating systems and architectures are available to download from GitHub Releases. If you wish to compile from source then you will need a suitable Go toolchain installed. After that just clone the project using Git and run Make! Cross-compilation is easy in Go so by default we build for all targets and place the resulting executables in ./bin:

git clone https://github.com/CHTJonas/whoami-dns.git
cd whoami-dns
make clean && make all

Copyright

whoami-dns is licensed under the BSD 2-Clause License.

Copyright (c) 2021 Charlie Jonas.