Router compatibility
JustASRV speaks the DynDNS v2 (dyndns2) update protocol over HTTPS, the de-facto standard that most firewalls and DDNS clients implement for "custom" providers. If a device supports a custom dyndns2 server with a username and password, it works with JustASRV.
Values for any dyndns2 client
| Protocol | DynDNS v2 / dyndns2, HTTPS |
| Server | ddns.justasrv.com |
| Path | /nic/update |
| Username | the full hostname, e.g. acme-main.ddns.justasrv.com |
| Password | the token (jas_…) |
| Hostname | the full hostname |
| Check-IP URL | https://ddns.justasrv.com/ip (plain-text answer) |
Compatibility summary
| Platform | Native support | Heartbeat | Guide |
|---|---|---|---|
| pfSense (CE / Plus) | Yes: Custom provider | No (updates on change + daily with Max Cache Age 1) | pfSense |
| OPNsense | Yes: os-ddclient, dyndns2 | No (updates on change) | OPNsense |
| MikroTik RouterOS 6.43+ / 7 | Yes: scheduled script | Yes | MikroTik |
| OpenWrt (ddns-scripts) | Yes: custom update URL | Yes (force interval) | OpenWrt |
| UniFi (UniFi OS gateways) | Partial: see guide | No | UniFi |
| Fortinet, SonicWall, consumer routers | Varies / often no | n/a | Other devices |
| ddclient, inadyn | Yes: dyndns2 | Configurable | Other devices |
| Windows / Linux machine at the site | JustASRV updater | Yes (every 10 min) | Windows · Linux |
Heartbeat vs. change-only
Some clients report only when the address changes. That is fine for DNS, but JustASRV cannot tell a quiet site from a dead one. For those hosts, an administrator sets longer status thresholds on the hostname (Host → Settings), or adds a heartbeat updater at the site. Each guide gives recommended values.
Addresses and NAT
By default JustASRV publishes the address the update request came from and ignores a myip= value that differs. This is correct for almost every site and cannot be spoofed. If an updater's traffic leaves through a different connection than the one the hostname should point to (for example, a dual-WAN site with a policy route), an administrator can switch that host to "accept public myip=". Private, loopback, CGNAT (100.64.0.0/10) and reserved addresses are always refused.