To check whether a server is using the weak ssh-rsa public key algorithm, for host authentication, try to connect to it after removing the ssh-rsa algorithm from ssh(1)'s allowed list:
ssh -oHostKeyAlgorithms=-ssh-rsa user@host
If the host key verification fails and no other supported host key types are available, the server software on that host should be upgraded.
To check whether a server is using the weak ssh-rsa public key algorithm, for host authentication, try to connect to it after removing the ssh-rsa algorithm from ssh(1)'s allowed list:
ssh -oHostKeyAlgorithms=-ssh-rsa user@host
If the host key verification fails and no other supported host key types are available, the server software on that host should be upgraded.