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.
Descrição
The data connection is already open and the transfer is beginning. No need to open a new data connection.
Quando você o vê
When the server reuses an existing data connection for a file transfer instead of opening a new one.
Como corrigir
No fix needed — the transfer is starting immediately. Your client should begin reading or writing data on the existing connection.
Descrição
Can't open data connection. The server was unable to establish the data channel needed for the file transfer.
Quando você o vê
When a firewall or NAT is blocking the data connection, or the client failed to connect to the server's passive port.
Como corrigir
Switch between active (PORT) and passive (PASV) modes. Check that your firewall allows the FTP data port range and that NAT is configured correctly.
Diferenças principais
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.
Quando usar qual
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.