Ive correctly configured passive FTP but passive data connections still fail. What else could be wrong?
Many of the newer, “smarter” routers attempt to detect passive FTP traffic and automatically modify the FTP commands to work correctly with the router. One way to diagnose this issue is to monitor the log file from Cerberus and the FTP client as a passive connection is attempted. The log file excerpts below are from a connection attempt from a Filezilla FTP client to Cerberus FTP Server. The client is located outside the local network Cerberus FTP Server is installed on. Cerberus: May 01 13:12:04 42 257 “/” is the current directory May 01 13:12:04 42 TYPE A May 01 13:12:04 42 200 Type ASCII May 01 13:12:04 42 PASV May 01 13:12:04 42 227 Entering Passive Mode (X,X,X,X, 7,255) May 01 13:12:04 42 LIST Filezilla: Command: TYPE A Response: 200 Type ASCII Command: PASV Response: 227 Entering Passive Mode (X,X,X,X,130,128) Command: LIST The indication that the router is changing the FTP command is the difference in the ports listed between the client log and the server log. To resolve the iss
Many of the newer, “smarter” routers and firewalls attempt to detect passive FTP traffic and automatically modify the FTP commands to work correctly with the router or firewall device. Specifying the public IP for passive command responses can cause problems with these routers and firewalls. If you are certain that you’ve correctly setup port forwarding and you are still having problems with passive FTP then this might be your problem. One way to diagnose this issue is to monitor the log file from Cerberus and the FTP client as a passive connection is attempted. The log file excerpts below are from a connection attempt from a popular FTP client to Cerberus FTP Server. The client is located outside of the local network Cerberus FTP Server is installed on.
