ポート 1433 — MSSQL (TCP)
What is Port 1433?
Microsoft SQL Server のデータベースインスタンス。
This is a registered port (1024–49151) often assigned to vendor or application services like MSSQL. · No formal RFC; Microsoft TDS protocol
When do you need Port 1433 open?
Open only if SQL Server must accept connections from external hosts — for example, a remote application server. Never expose SQL Server directly to the internet. Use a VPN or SSH tunnel and keep this port closed to public traffic.
Common uses and software
- Microsoft SQL Server
- Azure SQL Database (via gateway)
- SQL Server Management Studio (SSMS)
- Entity Framework
- ADO.NET
Security
Never expose port 1433 directly to the internet. Use a VPN or SSH tunnel for remote database access. Disable the SA account or rename it and use a strong password. Enable SQL Server Audit logging. Restrict client IP addresses in Windows Firewall. Prefer Windows Authentication over SQL authentication where possible.
Is Port 1433 safe?
An open port increases your attack surface. Safety depends on how MSSQL is configured.
Low risk, but confirm that MSSQL on this port is intentionally running and required by your application before leaving it open.
Test connectivity for Port 1433 on any host.
How to Open Port 1433
To allow incoming connections to Port 1433 (MSSQL) from outside your network, configure your firewall and add a port forwarding rule on your router pointing to your device's local IP address.
Open Windows Defender Firewall → Advanced Settings → Inbound Rules → New Rule → Port → TCP → Specific local ports: 1433 → Allow the connection → Name and save the rule.
netsh advfirewall firewall add rule name="Open Port 1433" dir=in action=allow protocol=tcp localport=1433sudo ufw allow 1433/tcpsudo iptables -A INPUT -p tcp --dport 1433 -j ACCEPTLog into your router (192.168.1.1 or 192.168.0.1) → Port Forwarding → Add a new rule: Protocol TCP, External port 1433, Internal IP: your device's local IP, Internal port 1433 → Save.
How to close Port 1433
If you do not need MSSQL, block this port in your firewall or router.
To block port 1433 on Windows, run the following command in PowerShell or Command Prompt (as Administrator):
netsh advfirewall firewall add rule name="Block Port 1433" dir=in action=block protocol=tcp localport=1433sudo ufw deny 1433/tcpsudo iptables -A INPUT -p tcp --dport 1433 -j DROPRemove or disable any port forwarding rule for Port 1433.
Frequently Asked Questions
What is Port 1433 used for?▾
Port 1433 is the default TCP port for MSSQL. It is used by servers and applications that need to accept incoming connections for this service. Whether you need it open depends on whether you are actively running a MSSQL server — if not, it should remain closed to reduce your attack surface.
Is Port 1433 safe to keep open?▾
An open Port 1433 increases your attack surface. If you are not actively running MSSQL, close this port in your firewall and remove any port forwarding rules. If MSSQL must be accessible, restrict access to known IP ranges, keep the service software updated with security patches, and use strong authentication.