When connecting to an older SSH device the following 'unable to negotiate' errors occurred. They indicate that my client-side config does not allow the (old/obsolete) methods offered by the device.

Unable to negotiate with 10.222.23.2 port 22: no matching key exchange method found. Their offer: diffie-hellman-group-exchange-sha1,diffie-hellman-group1-sha1,diffie-hellman-group14-sha1

This can be fixed by enabling one of the old key exchange methods:

ssh -oKexAlgorithms=+diffie-hellman-group1-sha1 10.222.23.2 

Unable to negotiate with 10.222.23.2 port 22: no matching host key type found. Their offer: ssh-rsa,ssh-dss

This can be fixed by additionally enabling one of the old host key types:

ssh -oKexAlgorithms=+diffie-hellman-group1-sha1 -oHostKeyAlgorithms=+ssh-rsa 10.222.23.2