How do I kill the process using port 445?

On macOS & Linux, run: "sudo systemctl stop smbd". On Windows PowerShell (as Admin), run: "Stop-Service LanmanServer -Force".

Why am I getting "port 445 already in use" (EADDRINUSE)?

This occurs when another background instance of System (ntoskrnl.exe), smbd or a zombie process is already bound to port 445. Use the kill commands above to free the port immediately.

Networking

Risk: Critical

Port 445 — Microsoft SMB / CIFS File Sharing

Q: Is Port 445 safe to expose to the public internet?

Risk level is Critical. Port 445 has been the primary attack vector for major ransomware and worms (WannaCry, EternalBlue, NotPetya). NEVER expose port 445 to the public internet.

Port 445 provides direct TCP hosting for Server Message Block (SMB) file and printer sharing in Windows, Samba, and enterprise NAS systems without requiring NetBIOS.

PORT NUMBER

445

PROTOCOL

TCP

DEFAULT PROCESS

System (ntoskrnl.exe), smbd

FIREWALL TARGET

445/tcp

Instant Terminal Fixes for Port 445

macOS & Linux Terminal

1. Check who is listening on port 445:

sudo lsof -i :445 || sudo ss -tulpn | grep ":445 "

2. Kill process occupying port 445 (EADDRINUSE fix):

sudo systemctl stop smbd

3. UFW Firewall Allow rule:

sudo ufw deny 445/tcp

Windows PowerShell (Admin)

1. Check listening port:

Get-NetTCPConnection -LocalPort 445

2. Force kill process on port 445:

Stop-Service LanmanServer -Force

3. Docker Port Forwarding Mapping:

docker run -d -p 445:445 dperson/samba

Common Error Encountered

System error 53 has occurred. The network path was not found on port 445.

Security Advisory & Hardening

Port 445 has been the primary attack vector for major ransomware and worms (WannaCry, EternalBlue, NotPetya). NEVER expose port 445 to the public internet.

Frequently Asked Questions

Port 445 Questions & Answers

Common questions regarding default services, kill commands, and firewall configurations.

Port 445 is commonly used for Microsoft SMB / CIFS File Sharing. Port 445 provides direct TCP hosting for Server Message Block (SMB) file and printer sharing in Windows, Samba, and enterprise NAS systems without requiring NetBIOS.

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