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FS#67742 - [openssh]Really slow speed while transfering a file with scp or sftp.

Attached to Project: Arch Linux
Opened by Frederic Bezies (fredbezies) - Friday, 28 August 2020, 10:23 GMT
Last edited by freswa (frederik) - Friday, 28 August 2020, 13:22 GMT
Task Type Bug Report
Category Packages: Core
Status Assigned
Assigned To Lukas Fleischer (lfleischer)
Levente Polyak (anthraxx)
Giancarlo Razzolini (grazzolini)
Architecture All
Severity Low
Priority Normal
Reported Version
Due in Version Undecided
Due Date Undecided
Percent Complete 0%
Votes 0
Private No


Description: I can't get more than 800kbps/s after testing on many machines using ArchLinux in upload with scp or sftp.

Tests in virtual machines from Ubuntu or debian or Fedora show a maximum upload line speed of 64MB/s.

To check I tested Manjaro or Arch in virtual machine and even bug less than 1mo/s in upload.

Additional info:
openssh 8.3p1-3

Steps to reproduce:
This task depends upon

Comment by loqs (loqs) - Saturday, 29 August 2020, 17:11 GMT
If you build the same version of openssh Arch uses with the locally applied patches on Ubuntu / Debian / Fedora what speed does that produce?
What about the reverse the package as the other distributions shipped it, built on Arch?
Comment by Frederic Bezies (fredbezies) - Saturday, 29 August 2020, 17:33 GMT
As far as I know, it works with Ubuntu 20.04 (Openssh 8.2) and the one for Ubuntu 20.10 (Openssh 8.3), but it doesn't with Fedora 32 (Openssh 8.3). All these distributions were tested in docker environment.

This bug can be seen with all Openssh 8.xx version in Archlinux.
Comment by loqs (loqs) - Saturday, 29 August 2020, 17:51 GMT
What if you force Ubuntu / Debian to use the same IPQoS as Arch / Fedora? [1]
If not [2] [3] [4] contain patches uses by Debian Fedora and Arch respectively.
I think the following should change the IPQoS to the settings Arch / Fedora use.
ssh -o IPQoS='af21 cs1'

Comment by Frederic Bezies (fredbezies) - Saturday, 29 August 2020, 19:31 GMT
If I add 'ssh -o IPQoS='af21 cs1' -> this makes the bug appear on Debian. It looks like you nailed the bug.

Edit: if I applied Debian patch "revert-ipqos...", it fixes the bug.
Comment by Giancarlo Razzolini (grazzolini) - Thursday, 29 October 2020, 21:23 GMT
This bug does seem to happen only on very particular scenarios, like described on the debian patch, it seems to affect only when you're interacting with iptables and some virtualization, I guess docker would trigger these too. I'm not very fond of applying this patch to Arch package.