Script to create encrypted rsa keys and server profile (alias) in your ssh_config.

generate_ssh_rsa_keys.sh

#!/usr/bin/env bash
#
# Script to create rsa keys and server profile (alias) in your ssh_config.
#
# created date:     20.03.2016
# last update date: 11.05.2017
# author:           @yugoslavskiy
#

usage () {
  echo "
  Description:
      Script to create rsa keys and server profile (alias) in your ssh_config.
  
  Usage:
      $(basename "$0") -s <server name> -i <ip address / domain name> [-u user_name] [-p port] [-c /path/to/ssh_config]
  
  Where:
      -h    show this help message
      -s    set ssh server name (just for alias)
      -u    set user name for ssh connection (default: ${USER})
      -i    set ip address / domain name of ssh server
      -p    set ssh port (default: 22)
      -c    set full path to ssh_config (default: ${ssh_congig_file})"
}

# default parametrs
#[[ -e /etc/ssh/ssh_config ]] && ssh_congig_file=/etc/ssh/ssh_config 
[[ -e /etc/ssh/ssh_config ]] && ssh_congig_file="${HOME}/.ssh/config"
[[ -n ${ssh_congig_file} ]] || ssh_congig_file=None
port=22
user_name=${USER}

while getopts ':hs:u::i:p::c::' option; do
  case "$option" in
    h) usage; echo '' ; exit ;;
    c) ssh_congig_file=$OPTARG ;;
    p) port=$OPTARG ;;
    s) name_of_server=$OPTARG ;;
    u) user_name=$OPTARG ;;
    i) ip_address=$OPTARG ;;
    :) printf "missing argument for -%s\n" "$OPTARG" >&2; usage; exit 1 ;;
   \?) printf "illegal option: -%s\n" "$OPTARG" >&2; usage; exit 1 ;;
  esac
done
shift $((OPTIND - 1))

if [[ ! "${name_of_server}" ]] && [[ ! "${ip_address}" ]]; then
    echo -e "\nYou have to give me more parametrs!\n"
    usage
    exit 1
elif [[ "${ssh_congig_file}" == "None" ]]; then
    echo -e "\nYou have to give me full path to ssh_config file (${ssh_congig_file} doesn't exists)\n"
    usage
    exit 1
fi

# generate keys
new_ssh_key=$HOME/.ssh/id_rsa_${name_of_server}_$(date +%Y-%m-%d)
ssh-keygen -t rsa -b 4096 -N '' -f ${new_ssh_key} -C "key for ${name_of_server}"

# encrypt private key with openssl
mv ${new_ssh_key} ${new_ssh_key}.old
openssl pkcs8 -topk8 -v2 des3 -in ${new_ssh_key}.old -out ${new_ssh_key}
rm -f ${new_ssh_key}.old

chmod 0600 $new_ssh_key*

# Ask for the administrator password if needed
[[ -w ${ssh_congig_file} ]] || {
    printf "\nI need root password for access to ${ssh_congig_file}:\n"
}

echo -e "
###############################################
# generetad with generate_ssh_rsa_keys script #
###############################################
Host ${name_of_server}
    HostName ${ip_address}
    Port ${port}
    User ${user_name}
    IdentityFile ${new_ssh_key}" | tee -a ${ssh_congig_file} >& /dev/null

printf "\nSo, what new in ${ssh_congig_file}:\n\n"

tail -n 8 ${ssh_congig_file}

printf "\nNow you can use ssh-copy-id tool to copy your new public key to ${name_of_server} server:\n"
printf "\$ ssh-copy-id ${name_of_server}\n"

exit 0