Port 3306

What’s running on port 3306 on my Mac?

Q: How do I change MySQL's port on a Mac?

Add `port = 3307` under `[mysqld]` in `/opt/homebrew/etc/my.cnf` and restart with `brew services restart mysql`. Clients then connect with `mysql -h 127.0.0.1 -P 3307`.

Q: Why does `mysql -P 3307` still connect to the wrong server?

With `-h localhost`, the client uses the Unix socket and ignores the port. Use `-h 127.0.0.1` to force TCP.

3306 is MySQL’s port, and MariaDB’s too. The usual questions are which install owns it (you may have two) and whether it’s listening on more than localhost.

Updated November 9, 2026

Commonly used by

MySQLThe server (mysqld) listens on 3306; the X Protocol uses 33060.
MariaDBDrop-in replacement, same default port, same mysqld/mariadbd process.
DBngin / MAMP / Laravel HerdLocal database managers that run their own MySQL on 3306.
Docker mysql imagePublished with -p 3306:3306, it shows up as com.docker.backend.

Check what’s on port 3306

lsof -nP -iTCP:3306 -sTCP:LISTEN

mysqld or mariadbd is a native install. Find out which one from its path:

ps -o pid,command -p <PID>

A path under /opt/homebrew is Homebrew (brew services list shows it). Paths inside /Applications/DBngin.app or /Applications/MAMP point to those apps. com.docker.backend or OrbStack means a container; docker ps --filter publish=3306 names it.

With Stat Space: statspace port 3306.

Free it or move it

Install	Stop it	Change the port
Homebrew	`brew services stop mysql`	`port = 3307` under `[mysqld]` in `/opt/homebrew/etc/my.cnf`
Docker	`docker stop <name>`	`-p 127.0.0.1:3307:3306`
DBngin / MAMP	Stop from the app	Port field in the app’s settings

Two MySQL servers on one Mac is common after trying several tools. They don’t share data, so a “missing database” is often just the wrong server.

Security: never expose 3306

A database on 0.0.0.0 is a much bigger risk than a dev web server. Anyone on the same Wi-Fi can try passwords against it, and a local root account with an empty or weak password is the norm in development.

Homebrew’s my.cnf ships with bind-address = 127.0.0.1. Keep it.
Docker’s -p 3306:3306 listens on every interface. Write -p 127.0.0.1:3306:3306 instead, or in Compose: "127.0.0.1:3306:3306".
Check with lsof: you want 127.0.0.1:3306, never *:3306.

More in dev server exposed to the network.

Seeing it live

Stat Space shows 3306 with the install behind it and flags it if it’s bound to all interfaces. With Pro, a Docker-published MySQL shows the container name and image instead of com.docker.backend.

Questions

Why does MySQL say port 3306 is already in use?

Another MySQL is already running: a Homebrew service, DBngin, MAMP or a Docker container. Run lsof -nP -iTCP:3306 -sTCP:LISTEN, then stop the one you don't want with brew services stop mysql or docker stop <name>.

How do I change MySQL's port on a Mac?

Add port = 3307 under [mysqld] in /opt/homebrew/etc/my.cnf and restart with brew services restart mysql. Clients then connect with mysql -h 127.0.0.1 -P 3307.

Why does mysql -P 3307 still connect to the wrong server?

With -h localhost, the client uses the Unix socket and ignores the port. Use -h 127.0.0.1 to force TCP.

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