Windows ports
8 windows ports: what each one does, its protocol, and whether it is secure by default.
SubnetKit lists 8 windows ports, using TCP, UDP, TCP/UDP. 8 of 8 are formally registered with IANA rather than just a widely followed convention.
1 of the 8 windows ports is encrypted by default; the rest send data in clear text unless wrapped in TLS, SSH, or a VPN.
Click any port below for its full page: what it does, its protocol, and whether it is safe to expose.
| Port | Service | Protocol | What it does |
|---|---|---|---|
| 135 | MS-RPC | TCP | Microsoft RPC endpoint mapper |
| 137 | NetBIOS-NS | UDP | NetBIOS Name Service |
| 138 | NetBIOS-DGM | UDP | NetBIOS Datagram Service |
| 139 | NetBIOS-SSN | TCP | NetBIOS Session Service |
| 445 | SMB | TCP | SMB / CIFS file sharing |
| 1512 | WINS | TCP/UDP | Windows Internet Name Service |
| 3268 | Global Catalog | TCP | Microsoft Active Directory Global Catalog |
| 3269 | Global Catalog SSL | TCP | Global Catalog over SSL/TLS |
Frequently asked questions
Which ports are in the Windows category?
port 135 (MS-RPC), port 137 (NetBIOS-NS), port 138 (NetBIOS-DGM), port 139 (NetBIOS-SSN), port 445 (SMB), port 1512 (WINS), port 3268 (Global Catalog) and port 3269 (Global Catalog SSL).
How many windows ports does SubnetKit list?
8, covering TCP, UDP, TCP/UDP. 8 of them are formally registered with IANA.
Are windows ports secure by default?
1 out of 8 are encrypted by default. Check each port's page for its specific encryption status.
Which windows port has the lowest number?
Port 135 (MS-RPC). Port 135 is the Microsoft RPC endpoint mapper. Windows services use it to negotiate dynamic ports, which is why it is a frequent firewall and hardening target.