Monitoring IP addresses
Add these to your firewall allow-list so our checks are not mistaken for unwanted traffic. The list is machine-readable, so a rule can be built by a script rather than by email.
Our own vantage point
81.163.20.249— Russia, Moscow (ru-msk)
Last changed: 2026-09-16. Last confirmed by measurement: 2026-09-16.
Machine-readable:
/en/monitoring-ips.txt
— one address per line, comments start with #.
IPv6 is not used: all checks go out over IPv4.
What we cannot publish, and why
Only the Moscow vantage point is ours. Checks from the other regions go through check-host.net nodes: that pool does not belong to us, it changes between checks, and we cannot promise it will stay the same tomorrow.
Publishing those addresses would mean promising someone else’s infrastructure. An allow-list that works most of the time is worse than none: it looks like it works.
ru-spb— Russia (St. Petersburg)eu-de— Germanyus-east— USA (East)ap-sg— Singapore (Asia)eu-nl— Netherlands
If you need a guaranteed address list for these regions, tell us: standing up our own probes there is a question of schedule, not of configuration.
How the checks look from your side
- Ping is a plain ICMP Echo Request (three packets, five-second timeout) — not a TCP probe dressed up as a ping.
- We ping the address the name resolved to, not the name itself. This is deliberate — it closes DNS rebinding — and it has a side effect worth knowing: with several A-records, one check hits one address, not all of them.
- HTTP checks arrive with the User-Agent of our monitor, so they are easy to tell apart in your logs.