Using OpenSSH 7.0 with legacy SSH implementations

There’s a new version of OpenSSH out there recently.

In this new version, 7.0, the installation has deprecated ssh-dss and diffie-hellman-group1-sha1 key exchange method for security enforcement.

So, the best fix if you face issues would be updating your OpenSSH Servers to the most recent versions.

However, if you don’t have access to the servers configuration, there’s a temporary workaround for keep using the legacy implementations.

For the ssh-dss error, create an entry in your ~/.ssh/config with the following content:

Host somehost.example.org
    PubkeyAcceptedKeyTypes +ssh-dss

And, for the diffie-hellman-group1-sha1 error, the following entry:

Host somehost.example.org
    KexAlgorithms +diffie-hellman-group1-sha1

You could also add other hosts, followed by comma:

Host somehost.example.org, otherhost.example.org

Or even regular expressions and IP addresses:

Host app*.example.org, *.example.com, 192.168.0.1

That’s all, folks.