Network Routers

Certain network router operating systems can be configured to send regular HTTP(S) requests to ztn.sh healthchecks directly from the router. This is a handy way to monitor them: when the router loses its WAN connection, it will not be able to ping ztn.sh healthchecks, and ztn.sh healthchecks will notify you about the outage.

DD-WRT

DD-WRT is a Linux-based firmware for routers that runs on wide variety of router models. DD-WRT ships with a cron daemon and wget utility. You can enable the cron daemon and edit crontab in DD-WRT control panel, Administration › Management › Cron.

The crontab syntax on DD-WRT is:

[cron expression] [username] [command]

Example for sending a ping every minute:

* * * * * root wget https://ping.ztn.sh/your-uuid-here

Screenshot:

MikroTik RouterOS

MikroTik RouterOS is a router operating system used primarily on MikroTik network hardware. Among its many features is scripting support and a scheduler.

First, create a script in WebFig, System › Scripts › Add New. Use the following parameters:

• Name: ping (example, you can use a different name)
• Policy: read, test
• Source: /tool fetch url="https://ping.ztn.sh/your-uuid-here" output=none

Then, create a schedule in WebFig, System › Scheduler › Add New. Use parameters:

• Interval: 00:01:00 (one minute)
• Policy: read, test
• On Event: ping (the name of the script from the previous step)

Notes:

• The output=none parameter tells the system to discard response body. Without this parameter, the system will save response body to a file, which will additionally require the write policy.
• The "tool fetch" utility supports HTTPS URLs but does not verify TLS certificates by default. You can add check-certificate=yes parameter to require a valid TLS certificate. Note that RouterOS ships with no root CA certificates, so you will also need to load these.
• Here's the full list of options supported by "tool fetch".