Implement full support of OpenSSH/session rekeying on git.drupal.org

Problem/Motivation

Although this issue is reported as a Git issue, it actually relates to the underlying SSH transport protocol onto which Git relies.

I discovered recently that the OpenSSH client cannot establish a connection to git.drupal.org server. For example, with OpenSSH 6.2p2:

$ ssh -v your_ssh_username@git.drupal.org

Will initiate the connection, ask for your passphrase if relevant, and finally stop on the second rekeying request:

debug1: rekeying in progress

To determine whether my SSH client was the problem, I conducted similar tests with:

• github.com: $ ssh -v git@github.com
• bitbucket.org: $ ssh -v git@bitbucket.org

In both cases, this step passed successfully and the SSH connection was initialized and exited properly.

So from these results, my guess is that the SSH server used on git.drupal.org does not fully support session rekeying and prevents the connection to be established properly when using OpenSSH. The OpenSSH client then remains frozen and should be killed.

Unfortunately, it's not (yet) possible to disable session rekeying in the official OpenSSH client. This means that this client cannot be used (unpatched) when dealing with git.drupal.org, and it also means that it is not possible to push to Git repositories using OpenSSH as the SSH client, as SSH is currently the only transport protocol supported for write access.

However, as I remember that it was possible to use OpenSSH with git.drupal.org a few months ago, I believe that a recent update of OpenSSH introduced the session rekeying feature and created the problem with git.drupal.org

The system I used for these tests:

• Gentoo Linux on amd64
• OpenSSH 6.2p2

Proposed resolution

As OpenSSH is a popular SSH client, I propose to implement full support of session rekeying on git.drupal.org and improve support of latest OpenSSH versions.

Or alternatively, may other transport protocols be offered for Git write access?