The -o option instructs ssh-keygen to store the private key in the new OpenSSH format instead of the old (and more compatible PEM format). This is advisable, as the new OpenSSH format has an increased resistance to brute-force password cracking.
The -o option instructs ssh-keygen to store the private key in the new OpenSSH format instead of the old (and more compatible PEM format). This is advisable, as the new OpenSSH format has an increased resistance to brute-force password cracking.