# WHATPORT(445)

## NAME

port 445 — SMB — SMB file and print sharing, TCP 445.

Protocol: TCP  
IANA registry

## DESCRIPTION

Windows file servers, Samba, and macOS file sharing serve SMB2/SMB3 directly over TCP 445 — no NetBIOS session layer, unlike the legacy 137-139 ports. It carries file shares, printer shares, and named pipes used by Windows remote administration and domain traffic. It is on nearly every Windows host and any Linux box running smbd, which is why it dominates internal scans. It is also the port behind the best-known remote worm exploits (EternalBlue, WannaCry).

## EXPOSURE

**Do not expose.** SMB must never face the internet — it exposes credentials-bearing authentication and a long history of pre-auth remote code execution; keep it inside the LAN or behind a VPN.

## CHECK

```sh
smbclient -L //TARGET -N   # or: nc -vz TARGET 445
```

## SEE ALSO

- spec — [[MS-SMB2]: Server Message Block Protocol Versions 2 and 3](https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-smb2/5606ad47-5ee0-437a-817e-70c366052962) (learn.microsoft.com)
- source — [Samba (GitHub mirror)](https://github.com/samba-team/samba) (github.com)
- iana — [IANA Service Name and Transport Protocol Port Number Registry](https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml) (iana.org)

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