FTP upload encounters a Socket cannot connect problem.

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Regarding the issue that FTP Socket cannot connect:

The main difference between FTP's PORT and PASV modes is that the data port connection method is different. In FTP PORT mode, you only need to open ports 21 and 20 on the server, while FTP PASV requires opening all TCP ports greater than 1024 and port 21 on the server.

When a user cannot list files while using FTP to upload files, it may be caused by choosing to upload in PASV mode. Therefore, please change the upload mode to PORT. For the same software, different versions have slightly different setup methods, so you need to configure it according to the actual situation. (If you still cannot access after canceling pasv, please try selecting the “Use Firewall Access” option before pasv and try again.) As shown in the figure:

CuteFTP 5.0XP setup method:

1. Select Edit-->click Settings

2. Select Firewall-->click “PASV mode” to remove the checkmark from the checkbox-->click OK

If "Data connection closed, transfer aborted " appears after connecting, please select the Enable firewall access option

Setup methods for other FTP:

CuteFtpPro3.X setup method: Select Tools-->click Global Options-->select Connection-->select Data Connection Type as: PORT-->click OK

Cute FTP 3.5 English version: FTP—Settings—Options—Firewall, remove the checkmark from the checkbox before “PASV mode”.
Cute FTP3.5 Chinese version: FTP—Settings—Options—Firewall, remove the checkmark from the checkbox before “PASV mode (A)”.
Leap FTP2.7.2: Sites—Site Manager—Advanced, remove the checkmark from the checkbox before “Use PASV mode”.

FileZilla FTP can enable the default passive mode PASV in FTP's transfer mode, and check “Allow fallback to other transfer modes on failure”.

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