FTP Further Info & Troubleshooting

====================================================================================

Passive Port Range

Passive ports are used to allow multiple FTP connections  by moving open FTP connections from port 21 to a port specified in the passive port range (40,000-40,100 is the standard ANS passive port range ). See relevant panel/cli doc pages for specific info on how the passive port range can be set.

Calculating FTP that's being used for connection:

A telltale sign of FTP port issues is encountering a connection refused error when the FTP connection attempt enters passive mode. Typically this error will be outputted as follows:

 

We can use the numbers included in the error to calculate the port which the FTP connection has attempted to use.

80,244,185,220,156,149  

First 4 numbers are the server IP,   

Multiply 5th number by 256 = x  

X+6th number = passive port which is being used  

156x256=39936+149=40085  

------------------------------------------------------------------------------------------------------------------------------------------------