How to Open Port 3306 for MySQL Remote Access

MySQL uses port 3306 by default. If your database works locally but remote connections fail, the issue is often not MySQL itself — it is networking. Common causes include:

• 🔥 Firewall blocking TCP 3306
• 🔒 MySQL listening only on localhost
• ☁ Cloud security groups
• 🐳 Docker ports not exposed
• 🌐 Missing router forwarding

Step 1 — Check MySQL bind-address

MySQL often listens only on localhost. Open:

/etc/mysql/mysql.conf.d/mysqld.cnf

Look for:

bind-address = 127.0.0.1

Change to:

bind-address = 0.0.0.0

This allows MySQL to accept remote connections. Restart MySQL:

sudo systemctl restart mysql

Step 2 — Open Firewall Rules

Ubuntu UFW:

sudo ufw allow 3306/tcp

CentOS / Rocky Linux firewalld:

sudo firewall-cmd \
--permanent \
--add-port=3306/tcp

sudo firewall-cmd --reload

iptables:

iptables -A INPUT \
-p tcp \
--dport 3306 \
-j ACCEPT

Step 3 — Cloud Firewall Rules

If running MySQL in cloud infrastructure:

• AWS Security Groups
• Google Cloud Firewall
• Azure NSG
• Oracle Cloud Rules
• Hetzner Firewall
• OVH Cloud Firewall

Opening Linux firewall alone is often not enough. Cloud networking may still block access.

Step 4 — Docker Users

A very common issue. Bad:

docker run mysql

Good:

docker run \
-p 3306:3306 \
mysql

Without port mapping, MySQL stays isolated inside Docker.

Step 5 — Router Port Forwarding

Homelab users often need router forwarding. Example:

External:

3306 TCP

↓

192.168.1.50:3306

Verify your server uses a static LAN IP.

Port 3306 Open but Still Not Working?

Grant Remote Access Properly

Verify allowed hosts:

SELECT host,user
FROM mysql.user;

Bad:

'user'@'localhost'

Good:

'user'@'%'

Grant privileges:

GRANT ALL PRIVILEGES
ON database.*

TO 'user'@'%';

FLUSH PRIVILEGES;

Security Warning

Opening MySQL publicly can be dangerous. Prefer:

• 🔒 VPN access
• 🛡 IP allowlists
• 🔑 Strong passwords
• 🚫 Avoid exposing MySQL directly
• 🔐 TLS database connections

Final Checklist