FTP 220 Service Ready vs 551 Page Type Unknown
FTP 220 (Service Ready) is a 2xx Positive Completion response, while 551 (Page Type Unknown) is a 5xx Permanent Negative response. 220 indicates that service ready for new user. This is the greeting message sent by the FTP server when a client first connects. In contrast, 551 means that requested action aborted: page type unknown. The server does not recognize the requested page structure or format.
Описание
Service ready for new user. This is the greeting message sent by the FTP server when a client first connects.
Когда вы это видите
Immediately upon connecting to an FTP server. This is the welcome banner confirming the server is accepting connections.
Как исправить
No fix needed — the server is ready. Proceed with USER and PASS commands to authenticate.
Описание
Requested action aborted: page type unknown. The server does not recognize the requested page structure or format.
Когда вы это видите
When attempting a transfer with a page structure type the server does not support. This is extremely rare in modern FTP usage.
Как исправить
Switch to stream transfer mode (MODE S) and file structure (STRU F), which are universally supported by all FTP servers.
Ключевые различия
220 is a 2xx Positive Completion response, while 551 is a 5xx Permanent Negative response.
FTP 220: Service ready for new user. This is the greeting message sent by the FTP server when a client first connects.
FTP 551: Requested action aborted: page type unknown. The server does not recognize the requested page structure or format.
You encounter 220 when immediately upon connecting to an FTP server. This is the welcome banner confirming the server is accepting connections.
You encounter 551 when when attempting a transfer with a page structure type the server does not support. This is extremely rare in modern FTP usage.
Когда что использовать
For 220 (Service Ready): No fix needed — the server is ready. Proceed with USER and PASS commands to authenticate. For 551 (Page Type Unknown): Switch to stream transfer mode (MODE S) and file structure (STRU F), which are universally supported by all FTP servers.