Port 1433 (TCP) — Microsoft SQL Server
Tabular Data Stream (TDS) on TCP/1433 is the default client-to-database listener for Microsoft SQL Server and Azure SQL Managed Instance.
| Port Number | 1433 |
|---|---|
| Transport Protocol | TCP |
| Primary Service | Microsoft SQL Server |
| Standard / Specification | MS-TDS Protocol |
| IANA Port Range | Registered User Port (1024–49151) |
| Internet Exposure Risk | Critical database port; never expose TCP/1433 to 0.0.0.0/0. |
Firewall Architecture & Hardening Best Practices
Place SQL Server nodes in isolated private database subnets, allow TCP/1433 solely from application-tier security groups, and enforce Encrypt=True TLS connections.
Operational Troubleshooting Note
Avoid running the SQL Server Browser service on UDP/1434 unless legacy named instances strictly require dynamic port discovery.
Quick CLI Connectivity & Firewall Reference
# Test TCP/1433 reachability (Linux / macOS / PowerShell) nc -zv target.example.com 1433 Test-NetConnection -ComputerName target.example.com -Port 1433 # Allow restricted CIDR on Linux UFW firewall ufw allow from 10.0.0.0/8 to any port 1433 proto tcp
Planning firewall allowlists or VPN overlays? Use our IPv4 CIDR Calculator, MTU & TCP MSS Calculator, or WireGuard AllowedIPs Generator.
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