FTP 125 Data Connection Open vs 425 Can't Open Data Connection
FTP 125 (Data Connection Open) is a 1xx Positive Preliminary response, while 425 (Can't Open Data Connection) is a 4xx Transient Negative response. 125 indicates that the data connection is already open and the transfer is beginning. No need to open a new data connection. 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
The data connection is already open and the transfer is beginning. No need to open a new data connection.
เมื่อคุณพบเห็น
When the server reuses an existing data connection for a file transfer instead of opening a new one.
วิธีแก้ไข
No fix needed — the transfer is starting immediately. Your client should begin reading or writing data on the existing connection.
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
125 is a 1xx Positive Preliminary response, while 425 is a 4xx Transient Negative response.
FTP 125: The data connection is already open and the transfer is beginning. No need to open a new data connection.
FTP 425: Can't open data connection. The server was unable to establish the data channel needed for the file transfer.
You encounter 125 when when the server reuses an existing data connection for a file transfer instead of opening a new one.
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 125 (Data Connection Open): No fix needed — the transfer is starting immediately. Your client should begin reading or writing data on the existing connection. 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.