In Fedora, CentOS and probably many other Linux distros ssh-keygen; still defaults to RSA 2048. People have not yet realized that the newer, and also faster, elliptic curve cryptography is available; even between my peers I still see that many of them are using old and insecure RSA based keys. Since SSH clients support multiple keys transitioning to newer keys can be painless: create a new elliptic curve key; do not delete the old RSA key; once you login into a server swap the old key with the new one. Generating a new secure SSH key is pretty simple, just open a terminal and run: ssh-keygen -o -a 256 -t ed25519