Port 445: SMB
Windows file and printer sharing.
- Port
- 445
- Protocol
- TCP
- Service
- SMB
- Exposure
- Do not expose to the internet
What is port 445 used for?
File servers and Active Directory.
Is it safe to expose port 445 to the internet?
A frequent target for ransomware and worms. Never expose to the internet; block it at the perimeter.
If port 445 seems closed or unreachable
- Check that the SMB service is running and listening on port 445, not only on 127.0.0.1.
- Check the firewall on the host itself (Windows Defender Firewall, iptables, nftables, ufw) for a rule that allows TCP 445.
- If the host is behind a router, confirm the forwarding rule points to the correct internal address and that your internet provider does not use carrier-grade NAT.
- Test from outside your own network. A port can be open locally and blocked at the edge, or the other way round.
Using port 445 safely
Treat port 445 as an internal-only service. Reach it through a VPN or an SSH tunnel, restrict it by source address, and keep the software that listens on it patched.
Check whether port 445 is open on your host
The check connects from our server, so it shows what the internet can reach.
Open the port checker