I am trying to clone the git repository and i am getting error
Unable to negotiate with <server>: no matching key exchange method found.
Their offer: diffie-hellman-group1-sha1
fatal: Could not read from remote repository.
ssh -oKexAlgorithms=+diffie-hellman-group1-sha1 firstname.lastname@example.org -p 2222
Your problem is described in details here:
If the client and server are unable to agree on a mutual set of parameters then the connection will fail.
OpenSSH (7.0 and greater) will produce an error message like this:
Unable to negotiate with 127.0.0.1: no matching key exchange method found. Their offer: diffie-hellman-group1-sha1
ssh-keygen -t rsa -C <your comment>
now add the public key under your server account and try again.