It looks like Ubuntu 20 deprecated some old cryptographic stuff.
This will re-enable them:
diffie-hellman-group1-sha1
germain@mini1:~$ git clone git@****:repo.git
Clonage dans 'site.preview'…
Unable to negotiate with **** port 22: no matching key exchange method found. Their offer: curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group14-sha256
fatal: Impossible de lire le dépôt distant.
germain@mini1:~$ sudo nano ~/.ssh/config
Host *
KexAlgorithms=+diffie-hellman-group1-sha1
diffie-hellman-group14-sha1
Unable to negotiate with ***** port 22: no matching key exchange method found. Their offer: diffie-hellman-group14-sha1
germain@mini1:~$ sudo sh -c "echo \"KexAlgorithms diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1\" >>/etc/ssh/ssh_config.d/weak.conf"
