Updated 25 October 2026 · By the Upcertain team
Set it up
- Choose New monitor, then Port monitoring.
- Enter the host and the port, from 1 to 65535.
- Set the timeout (1 to 60 seconds) and the interval.
Common ports
| Service | Port |
|---|---|
| SMTP (submission) | 587, or 25 for server-to-server |
| IMAP over TLS | 993 |
| PostgreSQL | 5432 |
| MySQL | 3306 |
| Redis | 6379 |
| SSH | 22 |
| Game or custom servers | whatever the server listens on |
What it does and does not prove
A successful connection proves the host is reachable and something is listening on the port. It does not log in or run a query, so a database that accepts connections but refuses every query still looks up. For a deeper check, expose a small health endpoint that runs a query and monitor it over HTTP.
Failures
- Connection refused: the host answered but nothing listens on the port.
- TCP timeout: no answer at all, often a firewall dropping the connection or the host being down.
- DNS failure: the hostname did not resolve.
Security
Only monitor ports that are meant to be reachable from the internet. If your database should not be public, monitor it from inside your network with a heartbeat instead: a small job that checks the database and calls its heartbeat URL.