FTP 220 Service Ready vs 425 Can't Open Data Connection
FTP 220 (Service Ready) is a 2xx Positive Completion response, while 425 (Can't Open Data Connection) is a 4xx Transient 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, 425 means that can't open data connection. The server was unable to establish the data channel needed for the file transfer.
คำอธิบาย
Service ready for new user. This is the greeting message sent by the FTP server when a client first connects.
เมื่อคุณพบเห็น
Immediately upon connecting to an FTP server. This is the welcome banner confirming the server is accepting connections.
วิธีแก้ไข
No fix needed — the server is ready. Proceed with USER and PASS commands to authenticate.
คำอธิบาย
Can't open data connection. The server was unable to establish the data channel needed for the file transfer.
เมื่อคุณพบเห็น
When a firewall or NAT is blocking the data connection, or the client failed to connect to the server's passive port.
วิธีแก้ไข
Switch between active (PORT) and passive (PASV) modes. Check that your firewall allows the FTP data port range and that NAT is configured correctly.
ความแตกต่างหลัก
220 is a 2xx Positive Completion response, while 425 is a 4xx Transient 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 425: Can't open data connection. The server was unable to establish the data channel needed for the file transfer.
You encounter 220 when immediately upon connecting to an FTP server. This is the welcome banner confirming the server is accepting connections.
You encounter 425 when when a firewall or NAT is blocking the data connection, or the client failed to connect to the server's passive port.
ควรใช้อันไหนเมื่อไร
For 220 (Service Ready): No fix needed — the server is ready. Proceed with USER and PASS commands to authenticate. For 425 (Can't Open Data Connection): Switch between active (PORT) and passive (PASV) modes. Check that your firewall allows the FTP data port range and that NAT is configured correctly.