ssh

key gen

ssh-keygen -t rsa -b 4096 -C "d3vin.chen@gmail.com" -N "" -f /tmp/id_rsa

encrypt ssh private key

Use openssl to encrypt an unencrypted private ssh key. Don’t overwrite the unencrypted one if you don’t want to.

openssl rsa -aes256 -in /tmp/id_rsa -out /tmp/id_rsa.enc

script to modify sshd_config

Disable password auth.

file=/etc/ssh/sshd_config
cp -p $file $file.old &&
awk '
$1=="PasswordAuthentication" {$2="no"}
$1=="PubkeyAuthentication" {$2="yes"}
{print}
' $file.old > $file