FTP upload in passive mode not working, It opens data connection and times out with “Data channel timed out.”

Question

220 Microsoft FTP Service
user user
331 Password required for user.
pass pass
230-Directory has 543,777,456,128 bytes of disk space available.
230 User logged in.
pwd
257 "/" is current directory.
cwd aa6
250 cwd command successful.
pwd
257 "/aa6" is current directory.
pasv
227 Entering Passive Mode (*,*,*,*,201,182).
stor sampleprogram
150 Opening ASCII mode data connection.
425 Data channel timed out.

The above is the FTP done using command-line. When I check with FTP client there is a file with 0 size created.

Answer 1

There's a firewall or NAT between the client and the server that prevents a connection to the port 51638 (= 201 * 2^8 + 182).

If you are not able to transfer files to/from the server from anywhere/any other FTP client, the server was most likely not set up correctly. Particularly the Windows server firewall was not configured with a rule for a data port range. Another option is that the server is not aware of its external IP address. That would be the case, if the part you obfuscated (*,*,*,*) is not the same IP address you connected to.

See my article on FTP Connection Modes for explanation of the network issues with FTP data connection.

And particularly see my article on configuring IIS FTP Server for instructions on configuring the firewall and/or the external IP address.