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FTP Access problem. (resubmit question)

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3 replies

by eric.brown

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(new info at end)
I set up FTP access for a customer using ISA Server and double NAT from two specific Internet IP addresses. One is My Company and the other is a franchise location.

From My Company, I can ftp across the Internet, dir, put anddel files. From the other location, I can log in successfully, create a directory, change into that directory and run any other command, but I can NOT do an ls or dir. When I do, it simply says that the port command was successful and then nothing....it just sits there:
ftp> dir
200 PORT command successful.
150 Opening ASCII mode data connection for /bin/ls.

However, this same machine connects to another FTP server daily and drops off files. It also can connect to my personal FTP siteand do a dir or ls with no problems.
**NEW INFO**I'm trying to get this to work for a customer. BUT: They use a proprietary FTP scripting program that they cannot change into using passive FTP.*****

So, any ideas other than Passive FTP to make it work?

3 replies

by mshavrov

General theory on the problem is: you have TCP sessions established on TCP port 21, but port 20 does not work (for example, blocked). It may be not "blocked", but just "not-allowed". We had similar problem just a few weeks ago. Finally it was solvedwith "Passive FTP".

But since you already know about "Passive FTP mode" and it's not an option, you should look for network between these 2 sites. You should ensure that your routers between these 2 hosts do not block TCP Port 20. If you have access to both locations, you may try to watch and debug log files on routers when you are trying to establish session. If you have sniffers or network analizers, you may try to simulate traffic on port 20 between sites.

If you want to provide moredetails regarding your network configuration, you may send me an e-mail.

Good luck.

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