MikroTik RouterOS

RouterOS has no generic dyndns2 client, but /tool fetch supports HTTPS with Basic authentication (RouterOS 6.43 and later, and v7). A small script run by the scheduler does the job, including change detection and a heartbeat.

1. Trust the certificate chain

/tool fetch only verifies the server if the router trusts the issuing CA. Import Let's Encrypt's ISRG Root X1 certificate (/tool fetch url=https://letsencrypt.org/certs/isrgrootx1.pem, then /certificate import file-name=isrgrootx1.pem) and add check-certificate=yes to both fetch commands below. Newer RouterOS 7 releases also ship a built-in CA store; check /certificate settings on your version. Without either, the token still travels encrypted, but the server's identity is not verified.

2. Add the script

System › Scripts, name justasrv, policy read, write, test, policy:

:local fqdn "acme-main.ddns.justasrv.com"
:local token "jas_YOUR_TOKEN"
:global jasLastIp
:global jasBeat
:if ([:typeof $jasBeat] != "num") do={ :set jasBeat 0 }
:local ip ""
:do {
  :set ip ([/tool fetch url="https://ddns.justasrv.com/ip" mode=https output=user as-value]->"data")
} on-error={ :log warning "JustASRV: cannot reach ddns.justasrv.com" }
:set jasBeat ($jasBeat + 1)
# update on change, or every 2nd run (10 minutes with a 5-minute schedule) as a heartbeat
:if ($ip != "" && ($ip != $jasLastIp || $jasBeat >= 2)) do={
  :do {
    :local r ([/tool fetch url=("https://ddns.justasrv.com/nic/update?hostname=" . $fqdn) mode=https \
      user=$fqdn password=$token output=user as-value]->"data")
    :if ([:pick $r 0 4] = "good" || [:pick $r 0 5] = "nochg") do={
      :if ($ip != $jasLastIp) do={ :log info ("JustASRV: " . $r) }
      :set jasLastIp $ip
      :set jasBeat 0
    } else={ :log warning ("JustASRV: " . $r) }
  } on-error={ :log warning "JustASRV: update rejected (check token / hostname)" }
}

3. Schedule it

/system scheduler add name=justasrv interval=5m on-event=justasrv start-time=startup

Check Log for lines starting with JustASRV:. The default thresholds (stale 30 min) fit this schedule.