[Bug 1863930] Re: SSH 1.99 clients fail to connect to openssh-server 1:7.6p1-4ubuntu0.3

[Kyle Birkeland]

The easiest way I found to reproduce was to monkey patch the python
paramiko library.  I've attached a short script which can be used to
test a host.  It requires either python-paramiko or python3-paramiko to
run.

** Attachment added: "test_bug_1863930.py"
   https://bugs.launchpad.net/ubuntu/bionic/+source/openssh/+bug/1863930/+attachment/5332797/+files/test_bug_1863930.py

-- 
You received this bug notification because you are a member of Ubuntu
Foundations Bugs, which is subscribed to openssh in Ubuntu.
https://bugs.launchpad.net/bugs/1863930

Title:
  SSH 1.99 clients fail to connect to openssh-server 1:7.6p1-4ubuntu0.3

Status in openssh package in Ubuntu:
  Fix Released
Status in openssh source package in Bionic:
  New

Bug description:
  SSHD closes the connection and logs the error message below when a
  client presents a protoversion of "1.99":

      Protocol major versions differ for X.X.X.X port X:
  SSH-2.0-OpenSSH_7.6p1 Ubuntu-4ubuntu0.3 vs. SSH-1.99-XXX

  RFC 4253 only states that clients should treat a server's protoversion
  of "1.99" as equivalent to "2.0"; however, some backward-compatible
  clients send a protoversion of "1.99" and expect the server to treat
  it as "2.0".

  This regression was introduced in openssh-portable 7.6p1 from commit
  97f4d3083; fixes were implemented in commits 9e9c4a7e5 and c9c1bba06.
  I've attached a patch with both of those fixes.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/openssh/+bug/1863930/+subscriptions