Bug 1496808 – OpenSSH 7.4 doesn't work with WinSCP >= 5.10 clients

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Bug 1496808 - OpenSSH 7.4 doesn't work with WinSCP >= 5.10 clients

Summary:	OpenSSH 7.4 doesn't work with WinSCP >= 5.10 clients

Status:	CLOSED ERRATA

Aliases:	None

Product:	Red Hat Enterprise Linux 7
Classification:	Red Hat
Component:	openssh (Show other bugs)
Sub Component:
Version:	7.4
Hardware:	x86_64 Linux

Priority	unspecified Severity high
Target Milestone:	rc
Target Release:	---
Assigned To:	Jakub Jelen
QA Contact:	Stefan Dordevic
Docs Contact:	Mirek Jahoda

URL:
Whiteboard:
Keywords:

Depends On:
Blocks:	1432486 1476743
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Reported:	2017-09-28 08:55 EDT by Olli Rajala
Modified:	2018-04-10 14:20 EDT (History)
CC List:	5 users (show)

See Also:
Fixed In Version:	openssh-7.4p1-15.el7
Doc Type:	Bug Fix
Doc Text:	WinSCP 5.10 now works properly with OpenSSH Previously, OpenSSH incorrectly recognized WinSCP version 5.10 as older version 5.1. As a consequence, the compatibility bits for WinSCP version 5.1 were enabled for WinSCP 5.10, and the newer version did not work properly with OpenSSH. With this update, the version selectors have been fixed, and WinSCP 5.10 now works properly with OpenSSH servers.
Story Points:	---
Clone Of:
Environment:
Last Closed:	2018-04-10 14:19:11 EDT
Type:	Bug
Regression:	---
Mount Type:	---
Documentation:	---
CRM:
Verified Versions:
Category:	---
oVirt Team:	---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---

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External Trackers
Tracker	ID	Priority	Status	Summary	Last Updated
CentOS	0013935	None	None	None	2017-09-28 08:55 EDT
Red Hat Product Errata	RHSA-2018:0980	None	None	None	2018-04-10 14:20 EDT

Groups: None (edit)

Description Olli Rajala 2017-09-28 08:55:46 EDT

Description of problem:

Filed bug also to CentOS 7 ticket system (https://bugs.centos.org/view.php?id=13935) but here's the description also.

There is a bug in the current OpenSSH version in Centos7 (openssh-server-7.4p1-12.el7_4.x86_64) which prevents WinSCP >= 5.10 clients for connecting. This can be reproduced in our environment all the time.

The bug is described here: https://bugzilla.mindrot.org/show_bug.cgi?id=2748

Basically the issue is that OpenSSH has some compatibility things for older WinSCP versions but unfortunately 5.1* matches also for 5.10 and 5.11.

Here's the debug log from the server side:

"sshd[20338]: debug1: match: WinSCP_release_5.11.1 pat WinSCP_release_4*,WinSCP_release_5.0*,WinSCP_release_5.1*,WinSCP_release_5.5*,WinSCP_release_5.6*,WinSCP_release_5.7,WinSCP_release_5.7.1,WinSCP_release_5.7.2,WinSCP_release_5.7.3,WinSCP_release_5.7.4 compat 0x00004000"


Version-Release number of selected component (if applicable): OpenSSH 7.4, WinSCP 5.10 or newer


How reproducible: always


Steps to Reproduce:
1) Install openssh-server-7.4 to the server side and WinSCP 5.10 or newer to the client
2) Try to connect and it fails

Actual results:

Connection fails.

Expected results:

Connection is successful. 

Additional info:

Comment 2 Jakub Jelen 2017-10-02 04:48:43 EDT

This sounds like a good candidate to be fixed in the next update. It is a long-existing bug in OpenSSH, which was recently fixed upstream (after revealing itself).

Comment 4 Olli Rajala 2017-10-03 01:32:39 EDT

https://bugs.centos.org/view.php?id=13935#c30256

As I described here, it doesn't appear with the default config, but still appears with the OpenSSH 7.4 + WinSCP 5.11 (probably also with 5.10) when sshd config is altered regarding KexAlgorithms.

Comment 9 errata-xmlrpc 2018-04-10 14:19:11 EDT

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHSA-2018:0980

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