Restrict SSH

restrict-ssh.sh

#!/bin/bash


warning() {

sudo wall -n "[WARNING] SSH Configuration is about to change!"

echo -e "










\033[0;31m
                                      .++++++.
                                     :@@+==+@@:
                                    -@@:    :@@-
                                   =@%.      .%@=
                                  *@#          #@*
                                 #@*            *@#
                               .%@=              =@%.
                              .%@-      .++.      -@%.
                             :@@:       -@@-       :@@:
                            =@%.        -@@-        .%@=
                           +@#          :@@:          #@+
                          *@*            @@            *@*
                         #@+             @@             +@#
                       .%@-              #%              -@%.
                      :@@:               ..               :@@:
                     -@%.               :%%:               .%@-
                    =@#                  --                  #@=
                   *@*                                        *@*
                   #@*                                        *@#
                    *@#======================================#@*
                     =++++++++++++++++++++++++++++++++++++++++=
\033[0m
                                      WARNING

                            Changing SSH configuration
                    Please ensure that SSH-Keys are installed!
             Once services has been reloaded, access will be restricted

"
        echo -e "\033[1;33mChanges to SSH Configuration \033[0m \n"
        diff /etc/ssh/sshd_config /etc/ssh/sshd_config.bak
        echo -e "\n\n"

}


finalize() {
    echo "Reloading services"
    sudo systemctl reload ssh
    sudo systemctl reload sshd
    echo "\n\nDone!"
}


restrict() {
        cp -n /etc/ssh/sshd_config /etc/ssh/sshd_config.bak

        sed -i '/^UsePAM/s/yes/no/' /etc/ssh/sshd_config
        sed -i '/^ChallengeResponseAuthentication/s/yes/no/' /etc/ssh/sshd_config
        sed -i '/^PasswordAuthentication/s/yes/no/' /etc/ssh/sshd_config
        sed -i '/^PermitRootLogin/s/yes/no/' /etc/ssh/sshd_config

        warning
        read -p "Are you sure? " -n 1 -r
        echo    # (optional) move to a new line
        if [[ $REPLY =~ ^[Yy]$ ]]
        then
                finalize
        else
                revert
        fi
}


revert() {
        echo -e "\033[1;33m\n\nReverting changes \033[0m \n"
        cp -f /etc/ssh/sshd_config.bak /etc/ssh/sshd_config
        echo "\n\nDone!"
}

trap revert INT

restrict