Port 445 (SMB)
TCPServer Message Block — SMB listens on port 445 by default.
What is Port 445?
Port 445 is used by SMB (Server Message Block), the protocol for Windows file sharing, printer sharing, and inter-process communication. Starting with Windows 2000, SMB runs directly over TCP on port 445 without requiring NetBIOS (ports 137-139).
SMB on port 445 enables network file sharing, providing access to shared folders, printers, and named pipes. Modern SMB versions (SMB 2.0, 3.0, 3.1.1) include significant security improvements including encryption, pre-authentication integrity, and secure dialect negotiation. SMB 3 supports multichannel for improved performance.
Port 445 has been the target of major cyberattacks including the WannaCry and NotPetya ransomware, which exploited the EternalBlue vulnerability. It should never be exposed to the internet. Use SMB 3.x with encryption and require signing for all connections.
Port 445 Security
SMB on port 445 should be secured with appropriate access controls and monitoring. Ensure the service is only accessible from trusted networks by configuring firewall rules to restrict access. If the protocol supports encryption, enable TLS/SSL to protect data in transit.
Regularly update SMB to the latest version to patch known vulnerabilities. Monitor port 445 for unauthorized access attempts and implement rate limiting where possible. Follow the principle of least privilege when configuring access permissions.
How to Check Port 445
To check if port 445 is open on a remote host, use nmap: 'nmap -p 445 hostname'. For a quick TCP connection test, use: 'telnet hostname 445' or 'nc -zv hostname 445'. On Windows PowerShell, use: 'Test-NetConnection -ComputerName hostname -Port 445'.
To check if port 445 is listening on your local machine, use: 'netstat -tlnp | grep 445' on Linux, or 'ss -tlnp | grep 445'. On Windows, use: 'netstat -an | findstr 445'. For a comprehensive scan, use: 'nmap -sV -p 445 hostname' to detect the service version running on the port.
Related Ports
Frequently Asked Questions
What is port 445 used for?
Port 445 is the default port for Server Message Block (SMB). It is used for smb communication using the TCP protocol.
Is port 445 TCP or UDP?
Port 445 uses TCP. TCP is used because smb requires reliable, ordered data delivery.
Should port 445 be open?
Port 445 should only be open if you are actively running SMB. Close unused ports to reduce your attack surface. If needed, restrict access to trusted IP addresses using firewall rules.
How do I check if port 445 is open?
Use 'nmap -p 445 hostname' to scan remotely, or 'netstat -tlnp | grep 445' to check locally on Linux. On Windows, use 'Test-NetConnection -Port 445 hostname' in PowerShell.
How do I secure port 445?
Secure port 445 by restricting access with firewall rules, using encryption (TLS/SSL) where supported, keeping SMB updated, using strong authentication, and monitoring for unauthorized access attempts.
🔍 Check Your IP Address
While you're here, find out your public IP address, location, and ISP details instantly.
Check My IP →