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端口 21 — FTP 控制
- Port Number
- 21
- Service
- FTP 控制
- Protocol
- TCP
- Description
- FTP command control
FAQ
What are reserved ports?
Ports 0-1023 are Well-Known Ports requiring admin privileges. 1024-49151 are Registered Ports, 49152-65535 are Dynamic/Private Ports.
Why do some ports support both TCP and UDP?
TCP provides reliable connections (e.g., HTTP page loading), UDP provides fast transmission (e.g., DNS queries). Some services use both protocols for different tasks.