toydns

A tiny recursive DNS server in Rust, following dnsguide.

It listens on UDP 0.0.0.0:2053, parses incoming DNS queries, and resolves each one iteratively starting from a root nameserver (a.root-servers.net / 198.41.0.4) — following NS referrals and glue records, recursively resolving NS hostnames when no glue is provided.

Run

cargo run

Then, from another terminal:

dig @127.0.0.1 -p 2053 www.google.com

Test

cargo test

Capture packets (optional)

Capture a query:

nc -u -l 1053 > query_packet.txt &
dig +retry=0 -p 1053 @127.0.0.1 +noedns google.com

Get the matching response:

nc -u -w1 8.8.8.8 53 < query_packet.txt > response_packet.txt