FTP files get corrupted


I have this anoying issue that when I download a file with any ftp client, that is larger than about 300 mb, the file gets corrupt. The only time it does not do that is if I turn off the Comodo firewall.

In my filezilla log I do see

22:40:19	Status:	Starting download of /mike/TinyXP-Rev09.iso
22:40:22	Status:	ftpcontrolsocket.cpp(1820): Waiting for replies to skip before sending next command...   caller=0p26828e8
22:40:42	Error:	Connection timed out

I have added filezilla.exe to my trusted program, what else do I need to let through to Filezilla inorder for this to work? Thanks for any help :slight_smile:

Try using the FTP client policy for Filezilla. Does that help?

When it doesn’t help try temporarily disabling “Block fragmented IP datagrams” under Firewall → Advanced → Attack Detection Settings → Miscellaneous.

Thank you for the reply. I already had Filezilla set to the FTP Client policy :slight_smile: I just now tried the “Block Fragmented IP Datagrams” however I still had a corrupt file.

Thanks for your support

Any Ideas? I turned on Packet Checksum verification. But that didn’t help either :frowning:

I just downloaded a 599mb file and it worked fine, but then I tryed my 717 MB and 8 GB files it did not work. GRRR All I know is when I turn off the comodo firewall the file downloads perfectly.

When the error happens do you see things logged in the Firewall logs? They can be found under Firewall → Common Tasks → View Firewall Alerts. Please post a screenshot of them.

I went to Firewall Events and exported them. Hope that is what you mean. I see nothing wrong with the log.


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I asked the other mods to take a look to see if collective effort brings more clarity.

That would be great thanks!

Hi Mike,

Please make certain that your FTP client (whatever flavour you prefer) is set to passive (PASV) mode. This is almost mandatory if you’re behind a firewall because of the way FTP host negotiate receive port settings.

Hope this helps,
Ewen :slight_smile:

Here is more about FTP active v.s. passive

Thank you. Bookmarked for reference.

I will try, unfortunately you meet me right in between OS reinstall :slight_smile:

Keep us posted. We will still be here when you are ready.