WinSCP - Incoming Packet Garbled on Decryption

I am using WinSCP 4.1.5 (410)

When I try to download files larger than about 200KB I get the error:

Incoming Packet Garbled on Decryption

Looking in the KB I see that this was a problem with earlier versions of PuTTY with Globalscape servers. I am connecting to:

SSH implementation = 1.36 sshlib: GlobalScape

Is there a work around for this? Is it possible to set the max window size manually?

thanks.

I do not know of any workaround.

This issue is being tracked already.

Hi,

Trying to find a workaround...

My knowledge of SSH2 internal encrypted traffic pattern is not known to me and how SSH2 sets it's window settings. But I tried to see if I could change that of the Global Scape server by changing the TCP WINDOWS SIZE in it self. It did not work.

To try and see if I could affect the outcome I set some custom TcpWindowSizes in the Globalscape server we have. Apparently the EFTP server sets a the TcpWindowSize reg setting hard to 64240 instead of the windows usual auto window.

Neither changing it to auto window, 32786 or 16384 helped.

I'm actually only experinceing problem on Download from the server, not on upload. I can without a problem upload well above 50MB. This is of course valid from the description on the Putty page: https://www.chiark.greenend.org.uk/~sgtatham/putty/wishlist/ssh2-bug-maxpkt.html
As it's the server that will send to large packets.

Now I'll e-mail Mr. Prikryl and see if he is happy to provide 4.2 for additional testing.

Gustav Lind

This sounds like disimilar versions of SSH bumping heads. WinSCP will rely on the SSH key when SFTP and SCP are used. WinSCP defaults to SSH 2. Try setting it to use SSH 1 under the SSH section on the left and see if you have a successful connection. If you do, then create a session by hitting the 'save' button and store the settings.

Good luck!

Snapper Boy wrote:

This sounds like disimilar versions of SSH bumping heads. WinSCP will rely on the SSH key when SFTP and SCP are used. WinSCP defaults to SSH 2. Try setting it to use SSH 1 under the SSH section on the left and see if you have a successful connection. If you do, then create a session by hitting the 'save' button and store the settings.

This is due to fact that the Globalscape bug is in SSH-2 only.

turn firewall off

I faced a similar issue during one of the transfers. On investigating, it turned out to be a disk space issue, since, there wasn't enough free space in the target instance, it was leading to this error. On clearing up some space by removing some stale or unwanted files, I was able to rectify this issue, hence, would like to point this out for reference during future instances.

rd9011 wrote:

I faced a similar issue during one of the transfers. On investigating, it turned out to be a disk space issue, since, there wasn't enough free space in the target instance, it was leading to this error. On clearing up some space by removing some stale or unwanted files, I was able to rectify this issue, hence, would like to point this out for reference during future instances.

Thanks for sharing your finding. I've seen this before too.
I have added this to the documentation:
https://winscp.net/eng/docs/message_incoming_packet_was_garbled_on_decryption