FTP Troubleshooting

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FTP Passive Port RangeMode

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

If your FTP that's being used for connection:

A telltale sign of FTP port issuesclient is encounteringusing apassive connectionmode, refusedyou'll errorusually whensee an output similar to the FTPbelow. connection attempt enters passive mode. Typically this error will be outputted as follows:

We can use the numbers included in the errorthis to calculate the port being used for passive mode (which thewe FTPcan connectionthen hascheck attemptedfor toany use.restrictions on).

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  

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