localhost:3306 - MySQL and MariaDB Database Port

What is Port 3306?

Port 3306 is the standard MySQL database communication port assigned by IANA (Internet Assigned Numbers Authority).

Services Using Port 3306

MySQL Server - World's most popular open-source database
MariaDB Server - MySQL fork and drop-in replacement
Percona Server - MySQL-compatible database server
MySQL Cluster - High-availability database cluster
Amazon RDS MySQL - Cloud-hosted MySQL instances
Google Cloud SQL - Managed MySQL service

Connect to MySQL on Port 3306

MySQL Command Line Client

# Connect to MySQL on localhost
mysql -h localhost -P 3306 -u root -p

# Shorthand (defaults to localhost:3306)
mysql -u root -p

# Connect to specific database
mysql -h localhost -P 3306 -u root -p database_name

# Connect with password in command (insecure, for scripts only)
mysql -h localhost -P 3306 -u root -pYourPassword

# After connection, enter password when prompted
Enter password: ****
    

Check MySQL Status

# Windows (XAMPP)
# Check XAMPP Control Panel - MySQL should show "Running"

# Linux - Check MySQL service
sudo systemctl status mysql
sudo service mysql status

# Check MariaDB
sudo systemctl status mariadb

# Mac - Check MySQL
mysql.server status

# Check if MySQL is listening on port 3306
# Windows
netstat -ano | findstr :3306

# Linux/Mac
sudo lsof -i :3306
netstat -an | grep 3306
    

Default MySQL Credentials

Software	Username	Password	Host
XAMPP (Windows/Linux)	root	(blank/empty)	localhost
WAMP (Windows)	root	(blank/empty)	localhost
MAMP (Mac)	root	root	localhost
Linux (Fresh Install)	root	(set during install)	localhost
MySQL Workbench	root	(your password)	127.0.0.1

Database Connection Strings

PHP mysqli Connection

<?php
// mysqli_connect(host, username, password, database, port)
$conn = mysqli_connect("localhost", "root", "", "database_name", 3306);

// Check connection
if (!$conn) {
    die("Connection failed: " . mysqli_connect_error());
}
echo "Connected successfully";

// Close connection
mysqli_close($conn);
?>
    

PHP PDO Connection

<?php
try {
    $dsn = "mysql:host=localhost;port=3306;dbname=database_name";
    $username = "root";
    $password = "";
    
    $pdo = new PDO($dsn, $username, $password);
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    
    echo "Connected successfully";
} catch(PDOException $e) {
    echo "Connection failed: " . $e->getMessage();
}
?>
    

Node.js mysql2 Connection

// npm install mysql2
const mysql = require('mysql2');

const connection = mysql.createConnection({
    host: 'localhost',
    port: 3306,
    user: 'root',
    password: '',
    database: 'database_name'
});

connection.connect((err) => {
    if (err) {
        console.error('Error connecting:', err);
        return;
    }
    console.log('Connected to MySQL on port 3306');
});

// Execute query
connection.query('SELECT * FROM users', (err, results) => {
    if (err) throw err;
    console.log(results);
});

connection.end();
    

Python MySQL Connection

# pip install mysql-connector-python
import mysql.connector

try:
    connection = mysql.connector.connect(
        host='localhost',
        port=3306,
        user='root',
        password='',
        database='database_name'
    )
    
    if connection.is_connected():
        print('Connected to MySQL on port 3306')
        
        cursor = connection.cursor()
        cursor.execute('SELECT * FROM users')
        results = cursor.fetchall()
        
        for row in results:
            print(row)
        
        cursor.close()
        
except mysql.connector.Error as e:
    print(f'Error: {e}')
    
finally:
    if connection.is_connected():
        connection.close()
    

Java JDBC Connection

// Add MySQL Connector/J to classpath
import java.sql.*;

public class MySQLConnection {
    public static void main(String[] args) {
        String url = "jdbc:mysql://localhost:3306/database_name";
        String username = "root";
        String password = "";
        
        try {
            Connection conn = DriverManager.getConnection(url, username, password);
            System.out.println("Connected to MySQL on port 3306");
            
            Statement stmt = conn.createStatement();
            ResultSet rs = stmt.executeQuery("SELECT * FROM users");
            
            while (rs.next()) {
                System.out.println(rs.getString("name"));
            }
            
            conn.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}
    

Fix "Can't connect to MySQL server on localhost:3306"

Error: Connection refused

MySQL server is not running.

Windows XAMPP: Start MySQL in XAMPP Control Panel
Linux: sudo systemctl start mysql
Mac: mysql.server start
Check if MySQL service is enabled at startup
Review MySQL error logs for startup failures

# Start MySQL service
# Windows (XAMPP)
# Use XAMPP Control Panel GUI

# Linux - MySQL
sudo systemctl start mysql
sudo service mysql start

# Linux - MariaDB
sudo systemctl start mariadb

# Mac - MySQL
sudo mysql.server start
brew services start mysql

# Check if started successfully
sudo systemctl status mysql
    

Error: Access denied for user 'root'@'localhost'

Wrong username or password.

Verify username is correct (usually "root")
Check password - XAMPP default is blank
MAMP default password is "root"
Password may have been changed previously
User may not have permission to access database

# Reset MySQL root password
# Stop MySQL first
sudo systemctl stop mysql

# Start MySQL in safe mode (skip grant tables)
sudo mysqld_safe --skip-grant-tables &

# Connect without password
mysql -u root

# Change root password
USE mysql;
UPDATE user SET authentication_string=PASSWORD('newpassword') WHERE User='root';
FLUSH PRIVILEGES;
EXIT;

# Or use ALTER USER (MySQL 5.7+)
ALTER USER 'root'@'localhost' IDENTIFIED BY 'newpassword';
FLUSH PRIVILEGES;

# Restart MySQL normally
sudo systemctl stop mysql
sudo systemctl start mysql

# Test new password
mysql -u root -p
    

Error: Port 3306 already in use

Another MySQL instance or application is using port 3306.

Check for multiple MySQL installations
Look for MySQL Windows Service running
Another database server on port 3306
Previous MySQL instance not shut down properly

# Find what's using port 3306
# Windows
netstat -ano | findstr :3306
tasklist | findstr [PID]

# Stop MySQL Windows Service
net stop MySQL
sc config MySQL start= disabled

# Linux/Mac
sudo lsof -i :3306
sudo netstat -tulpn | grep 3306

# Kill process using port 3306
sudo kill -9 [PID]

# Stop MySQL service
sudo systemctl stop mysql
    

Access MySQL via GUI Tools

phpMyAdmin

URL: http://localhost/phpmyadmin
Web-based MySQL management interface
Included with XAMPP, WAMP, MAMP
Connects to MySQL on port 3306 automatically

MySQL Workbench

# Download from mysql.com
# Configure connection:
# Connection Name: Local MySQL
# Hostname: localhost or 127.0.0.1
# Port: 3306
# Username: root
# Password: (your password or blank)

# Test Connection button to verify
    

Other MySQL GUI Tools

HeidiSQL - Lightweight Windows MySQL client
DBeaver - Universal database tool (Windows/Linux/Mac)
TablePlus - Modern database client (Mac/Windows)
Sequel Pro - MySQL client for Mac
Adminer - Single-file phpMyAdmin alternative
DataGrip - JetBrains database IDE

Change MySQL Port from 3306

If port 3306 is occupied, change MySQL to different port:

Edit MySQL Configuration File

# Find my.cnf or my.ini file
# Windows XAMPP: C:\xampp\mysql\bin\my.ini
# Linux: /etc/mysql/my.cnf or /etc/my.cnf
# Mac: /usr/local/etc/my.cnf

# Edit configuration file
sudo nano /etc/mysql/my.cnf

# Find [mysqld] section and change port
[mysqld]
port = 3307

# Save and restart MySQL
sudo systemctl restart mysql

# Connect to new port
mysql -h localhost -P 3307 -u root -p

# Update application connection strings to use port 3307
    

Configure Firewall for Port 3306

Windows Firewall

# Allow MySQL port 3306
netsh advfirewall firewall add rule name="MySQL Port 3306" dir=in action=allow protocol=TCP localport=3306

# Remove firewall rule
netsh advfirewall firewall delete rule name="MySQL Port 3306"
    

Linux Firewall (UFW)

# Allow MySQL port 3306
sudo ufw allow 3306/tcp

# Allow from specific IP only
sudo ufw allow from 192.168.1.0/24 to any port 3306

# Check firewall status
sudo ufw status numbered

# Remove rule
sudo ufw delete allow 3306/tcp
    

Linux Firewall (firewalld)

# Allow MySQL service
sudo firewall-cmd --permanent --add-service=mysql
sudo firewall-cmd --reload

# Or allow port directly
sudo firewall-cmd --permanent --add-port=3306/tcp
sudo firewall-cmd --reload

# Check open ports
sudo firewall-cmd --list-all
    

Test MySQL Port 3306 Connection

# Test with telnet
telnet localhost 3306

# Test with netcat
nc -zv localhost 3306

# Test with mysql client
mysql -h localhost -P 3306 -u root -p

# Windows PowerShell
Test-NetConnection -ComputerName localhost -Port 3306

# Check if MySQL is listening
# Linux
sudo netstat -tulpn | grep :3306
sudo ss -tulpn | grep :3306

# Show MySQL process
ps aux | grep mysql
    

MySQL Configuration File Locations

System	Configuration File
XAMPP Windows	C:\xampp\mysql\bin\my.ini
XAMPP Linux	/opt/lampp/etc/my.cnf
Ubuntu/Debian	/etc/mysql/my.cnf
CentOS/RHEL	/etc/my.cnf
Mac (Homebrew)	/usr/local/etc/my.cnf
MAMP Mac	/Applications/MAMP/conf/my.cnf

MySQL Error Log Locations

# Find error log location
mysql -u root -p -e "SHOW VARIABLES LIKE 'log_error';"

# Common log locations:
# XAMPP Windows
C:\xampp\mysql\data\mysql_error.log

# Linux
/var/log/mysql/error.log
/var/log/mysqld.log

# Mac
/usr/local/var/mysql/[hostname].err

# View recent errors
tail -f /var/log/mysql/error.log
    

Allow Remote Connections to Port 3306

By default, MySQL only accepts connections from localhost. To allow remote access:

Edit MySQL Configuration

# Edit my.cnf or my.ini
sudo nano /etc/mysql/my.cnf

# Find and comment out or change bind-address
# bind-address = 127.0.0.1
bind-address = 0.0.0.0

# Save and restart MySQL
sudo systemctl restart mysql
    

Grant Remote Access to User

# Connect to MySQL
mysql -u root -p

# Create user for remote access
CREATE USER 'username'@'%' IDENTIFIED BY 'password';

# Grant privileges
GRANT ALL PRIVILEGES ON database_name.* TO 'username'@'%';

# Or grant from specific IP
CREATE USER 'username'@'192.168.1.100' IDENTIFIED BY 'password';
GRANT ALL PRIVILEGES ON database_name.* TO 'username'@'192.168.1.100';

# Apply changes
FLUSH PRIVILEGES;
EXIT;

# Test remote connection
mysql -h 192.168.1.100 -P 3306 -u username -p
    

Common MySQL Commands

# Show all databases
SHOW DATABASES;

# Create database
CREATE DATABASE mydb;

# Select database
USE mydb;

# Show tables in database
SHOW TABLES;

# Create table
CREATE TABLE users (
    id INT PRIMARY KEY AUTO_INCREMENT,
    name VARCHAR(100),
    email VARCHAR(100)
);

# Show table structure
DESCRIBE users;

# Insert data
INSERT INTO users (name, email) VALUES ('John', 'john@example.com');

# Query data
SELECT * FROM users;

# Show MySQL version
SELECT VERSION();

# Show current database
SELECT DATABASE();

# Show current user
SELECT USER();

# Show all users
SELECT User, Host FROM mysql.user;

# Exit MySQL
EXIT;
    

MySQL vs MariaDB on Port 3306

Feature	MySQL	MariaDB
Default Port	3306	3306
Compatibility	Oracle MySQL	MySQL drop-in replacement
License	GPL (community) / Commercial	GPL (fully open source)
Performance	Excellent	Slightly better
Storage Engines	InnoDB, MyISAM	InnoDB, MyISAM, Aria, more
Default in	Most hosting providers	Debian, SUSE, Arch Linux

Frequently Asked Questions

Can I access MySQL port 3306 in browser?

No. Port 3306 is for MySQL protocol, not HTTP. Use phpMyAdmin (http://localhost/phpmyadmin) or MySQL Workbench to manage databases through GUI.

Why can't I connect to MySQL on port 3306?

Common reasons: MySQL not running, wrong credentials, firewall blocking port, MySQL bound to 127.0.0.1 only, or port 3306 used by another service.

Is it safe to expose port 3306 to internet?

No. Never expose MySQL directly to internet. Use SSH tunneling, VPN, or restrict access by IP. Use strong passwords and disable root remote access.

Can I run MySQL on different port?

Yes. Edit my.cnf configuration file and change port number. Remember to update all application connection strings to use new port.

What's the difference between localhost and 127.0.0.1 for MySQL?

On MySQL, localhost uses Unix socket connection (faster), while 127.0.0.1 uses TCP connection on port 3306. Both work but localhost is preferred for same-machine connections.

Related Ports and Resources

localhost/phpmyadmin - Web-based MySQL management
localhost:5432 - PostgreSQL database port
localhost:27017 - MongoDB database port
localhost:6379 - Redis cache port
localhost:1433 - Microsoft SQL Server
localhost/xampp - XAMPP control panel
Connection Issues - Fix database problems