Windows FileShare Ports — Complete Reference
Windows file sharing uses specific network ports for SMB, CIFS, and NetBIOS protocols. If your Windows fileshare is blocked, it's usually because one of these ports is closed in your firewall.
All Windows FileShare Ports
| Protocol | Port | Type | Purpose |
|---|---|---|---|
| SMB (modern) | 445 | TCP | Main Windows file sharing port |
| CIFS | 445 | TCP | Same as SMB — legacy name |
| NetBIOS Session | 139 | TCP | Legacy SMB over NetBIOS |
| NetBIOS Name | 137 | UDP | Network name resolution |
| NetBIOS Datagram | 138 | UDP | Broadcast messages |
| FTP | 21 | TCP | File Transfer Protocol |
| SFTP/SSH | 22 | TCP | Secure file transfer |
| HTTPS (browser) | 443 | TCP | Browser-based file sharing |
Main Windows FileShare Port: 445
Port 445 (TCP) is the primary Windows fileshare port used by SMB and CIFS. All modern Windows file sharing goes through this port. If port 445 is blocked, Windows network file sharing will not work.
How to Open Windows FileShare Ports in Firewall
- Open Windows Defender Firewall → Advanced Settings
- Click Inbound Rules → New Rule → Port
- Select TCP → enter port 445 → Allow the connection
- Apply to Domain, Private, Public as needed
- Repeat for port 139 (TCP) and ports 137-138 (UDP)
Why Are Windows FileShare Ports Blocked?
- ISP blocking — many ISPs block port 445 to prevent ransomware (WannaCry used SMB)
- Corporate firewall — IT departments restrict SMB for security
- Windows Firewall — blocks SMB on public network profiles by default
FileShare Without Opening Ports
If you can't open SMB ports, use files-share.com — it transfers files over HTTPS (port 443) which is open on virtually every network. No firewall changes needed, no IT approval required.
FAQ
What port does Windows file sharing use?
Port 445 (TCP) for SMB/CIFS. Port 139 (TCP) for legacy NetBIOS. Ports 137-138 (UDP) for NetBIOS name service.
What is the Windows fileshare port number?
The main Windows fileshare port is 445 (TCP). This is used by both SMB and CIFS protocols.
How do I fix Windows file sharing blocked by firewall?
Open port 445 (TCP) in Windows Firewall. Or use files-share.com which works over HTTPS port 443 — no firewall changes needed.
What ports does CIFS use on Windows?
CIFS uses port 445 (TCP) — the same as SMB. CIFS is an older name for the SMB protocol.
Can I share files on Windows without opening port 445?
Yes. Use files-share.com — browser-based file sharing over HTTPS (port 443), no SMB ports needed.
Can't open fileshare ports? files-share.com works over HTTPS on any network — free, no account, up to 10GB.