1688 Microsoft KMSKey Management Service for Windows/Office volume activation.
Clients reach the KMS host on TCP/1688 to activate. Internal only.
| Transport | Status | Meaning |
|---|---|---|
| TCP | Unofficial | Not assigned by IANA, but 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. |
Registered (1024–49151). Assigned by IANA on request; usable without elevated privileges on most systems.
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