445 SMB / Microsoft-DSDirect-hosted SMB for Windows file sharing and Active Directory.
File shares, SYSVOL, group policy. NEVER expose to the internet (WannaCry/EternalBlue vector).
| Transport | Status | Meaning |
|---|---|---|
| TCP | Yes | Assigned by IANA and standardized, specified, or widely used on this port. |
| UDP | — | Not applicable for this transport. |
| SCTP | — | Not applicable for this transport. |
| DCCP | — | Not applicable for this transport. |
Well-known (0–1023). System port for a core service. On Unix-like systems, binding it requires superuser privileges.
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