When users employ ssh-keygen to create RSA key pairs, the default key length is 2048 bits.
You can override that on the command line with the -b argument, but few users will bother.
As mentioned in this article, it is recommended to use key lengths of 3072 or greater if you need security beyond 2030. Is there a way to cause 3072 (or 4096) to be the default length for all keys generated? I don't see it in the ssh_config or sshd_config manual pages. Or does it require recompilation of the program?