single-use-dns

Simple throwaway dns server that temporarily hosts records for a single domain name.

Useful to temporarily host a DNS record, such as a ACME DNS-01 challenge.

Example

$ single-use-dns --domain _acme-challenge.example.com --txt O_FFiiKTKtSYllnIKhXteCYji_d2vDk_FFiiKTKtSYl
Listening on [::]:53 (UDP and TCP)
Serving 1 record(s) for _acme-challenge.example.com

Using this with acme.sh

To use this tool with acme.sh, add a script like the following in ~/.acme.sh/dns_single_use.sh:

#!/usr/bin/env sh

dns_single_use_add() {
        single-use-dns --domain "$1" --txt "$2" &
}

dns_single_use_rm() {
        killall single-use-dns
}

Make sure the domain(s) you're going to use this with have an NS record for the _acme-challenge subdomain pointing to the server you run this on.

Then you should be able to run acme.sh with the --dns dns_single_use option:

$ acme.sh --issue --dns dns_single_use --dnssleep 0 -d '*.example.com'

You can add the --listen option to the single-use-dns command if you want it to listen on a specific ip-address instead of the wildcard address: --listen [fdff:1234:1234:1234::2]:53.

Without root on Linux

To allow this tool to handle traffic on the DNS port (UDP and TCP port 53) on Linux without running as root, you can give it the CAP_NET_BIND_SERVICE capability:

sudo setcap CAP_NET_BIND_SERVICE=+ep ./single-use-dns

Make sure only the user account(s) that should be allowed to run it can execute it.