Port 5432: PostgreSQL
Port 5432 is the default port for PostgreSQL databases.
What runs on port 5432
PostgreSQL listens on TCP 5432 for database connections. It powers many web apps and self-hosted services such as Nextcloud, Immich and Home Assistant's optional database setups.
On a home network
Home servers, NAS boxes running Docker, and Raspberry Pis hosting self-hosted apps may run PostgreSQL. It is usually meant to be reached only by the app on the same machine.
If port 5432 is reachable from the internet
A database should not be reachable from the internet. Exposed PostgreSQL servers are brute forced, and attackers who get in with a superuser account have used built-in features to run commands on the host and install cryptominers. Docker setups that publish 5432 on all interfaces are a common cause of accidental exposure.
How to check whether it is open on your network
Check whether a container or router rule publishes 5432, and look at listen_addresses in postgresql.conf. RECON's Exposure Check shows whether it answers from outside.
To find out whether port 5432 is open on something in your home, and whether the internet can reach it, the app scans your Wi-Fi from your phone and checks your public address from the outside. It says what it checked and what it could not. Get RECON for iPhone — one-time purchase, no account, nothing leaves the device.