bug with strandards RFC

We have a concern for download with your application. Apparently, FlashFXP doesn't meet the standards RFC FTP and makes transfers considered illegal by our firewall (that meet the FTP RFC).
FileZilla software and CyberDuck work very well. Have you ever heard of this problem and is a patch is programmed?

What firewall are you talking about?
What exact FTP RFC are you talking about?
What exactly does your firewall considers "illegal"?

FlashFXP existed for about 15 years. By now it's highly unlikely there's anything wrong with the way FlashFXP transfers files. It's more likely that your firewall is working in some paranoid mode. But provide more details and bigstar will evaluate if there's anything wrong and if there's a need for anything to be fixed.

Our Firewall are Fortinet

We have FlashFxp client working without protection profile, however once we enable the scanning on FTP, the file transfer across the FlashFxp fails
- At the same time, FileZilla works fine with or without protection profile

- For testing, we created a 'scan_clone' protection profile with AV enabled on FTP
- Created a Firewall policy with the new profile for a specific test PC
- When tried to transfer the file through FlashFxp, it failed
- Removed the FTP scanning, it worked fine
- Got some sniffer output and during the replication of the issue, saw that the FlashFXP didn't work with or without FTP scanning
- From the same PC, launched File Zilla client and was able to transfer the file without any issues

So we conclude that the issue is with the FlashFXP FTP client,

so far sounds like firewall configuration issue.

post session log from working filezilla and not working flashfxp to compare what they are doing differently.

As MxxCon suggested the server session logs might be a key factor in determining why FlashFXP doesn't work.

I look forward to seeing some log files for comparison.

After analysis of frames using different representative situations (with / without antivirus profile, with / without filtering the flow FTP, different FTP client, different sources / destinations) ensures that the expert Fortinet is the FlashFXP FTP client that is in question .

Indeed, some frame formats used by FlashFXP would not meet the exact specifications of the FTP protocol, resulting in poor detection (false positives) by the firewall

Can you please give us examples of which frames you detected that do not meet the exact specifications of the FTP protocol?

This report has been closed because the reporter hasn't replied with the requested information.