FTP 220 Service Ready vs 503 Bad Sequence
FTP 220 (Service Ready) is a 2xx Positive Completion response, while 503 (Bad Sequence) 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, 503 means that bad sequence of commands. The command is valid but was sent in the wrong order relative to other commands.
Mô tả
Service ready for new user. This is the greeting message sent by the FTP server when a client first connects.
Khi bạn thấy mã này
Immediately upon connecting to an FTP server. This is the welcome banner confirming the server is accepting connections.
Cách khắc phục
No fix needed — the server is ready. Proceed with USER and PASS commands to authenticate.
Mô tả
Bad sequence of commands. The command is valid but was sent in the wrong order relative to other commands.
Khi bạn thấy mã này
When you skip a required step, like sending PASS before USER, or RNTO without first sending RNFR.
Cách khắc phục
Follow the correct command sequence. Common sequences: USER then PASS for login, RNFR then RNTO for rename, PASV then RETR for transfer.
Sự khác biệt chính
220 is a 2xx Positive Completion response, while 503 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 503: Bad sequence of commands. The command is valid but was sent in the wrong order relative to other commands.
You encounter 220 when immediately upon connecting to an FTP server. This is the welcome banner confirming the server is accepting connections.
You encounter 503 when when you skip a required step, like sending PASS before USER, or RNTO without first sending RNFR.
Khi nào dùng cái nào
For 220 (Service Ready): No fix needed — the server is ready. Proceed with USER and PASS commands to authenticate. For 503 (Bad Sequence): Follow the correct command sequence. Common sequences: USER then PASS for login, RNFR then RNTO for rename, PASV then RETR for transfer.