RHEL Engineering is moving the tracking of its product development work on RHEL 6 through RHEL 9 to Red Hat Jira (issues.redhat.com). If you're a Red Hat customer, please continue to file support cases via the Red Hat customer portal. If you're not, please head to the "RHEL project" in Red Hat Jira and file new tickets here. Individual Bugzilla bugs in the statuses "NEW", "ASSIGNED", and "POST" are being migrated throughout September 2023. Bugs of Red Hat partners with an assigned Engineering Partner Manager (EPM) are migrated in late September as per pre-agreed dates. Bugs against components "kernel", "kernel-rt", and "kpatch" are only migrated if still in "NEW" or "ASSIGNED". If you cannot log in to RH Jira, please consult article #7032570. That failing, please send an e-mail to the RH Jira admins at rh-issues@redhat.com to troubleshoot your issue as a user management inquiry. The email creates a ServiceNow ticket with Red Hat. Individual Bugzilla bugs that are migrated will be moved to status "CLOSED", resolution "MIGRATED", and set with "MigratedToJIRA" in "Keywords". The link to the successor Jira issue will be found under "Links", have a little "two-footprint" icon next to it, and direct you to the "RHEL project" in Red Hat Jira (issue links are of type "https://issues.redhat.com/browse/RHEL-XXXX", where "X" is a digit). This same link will be available in a blue banner at the top of the page informing you that that bug has been migrated.

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:

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).

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.

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