228 lines
10 KiB
Bash
Executable File
228 lines
10 KiB
Bash
Executable File
#!/usr/bin/env bash
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# Ensure bash path is found
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# shellcheck source=/etc/os-release
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# use shellcheck to declare which file to source
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# Using set to make the script safer
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set -e # Exit on error
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set -u # Exit on undefined variable
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set -x # Print commands for debugging
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set -a # Export all variables
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set -C # Disable overwriting of files
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set -o pipefail # Exit on pipe error
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# set -euxaCo pipefail # All options
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# Use the built-in trap command to catch error lines and signal numbers
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trap 'printf "Error on line %d with signal %s" "$LINENO" "$?"' ERR # Exit on error
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# Also use trap to catch interrupt signals and exit cleanly with a message to the user and a return code
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trap 'printf "Interrupted on line %d with signal %s" "$LINENO" "$?"' INT SIGHUP SIGINT SIGTERM
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# Get script name using parameter expansion to not spawn a new subprocess
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SCRIPT_NAME="${0##*/}"
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# We will be using printf instead of echo because it is more standardised.
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# Also we will be using the test command's functionality as
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# [[ because like this it constitutes a keyword and not a command.
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# Functions will be defined as function "name" {body}" to make them
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# more clear and () will not be used since using the keyword function renders them redundant
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# We are taking for granted that the os-release file is in /etc as
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# it has become a standard in most GNU/Linux distributions using systemd.
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# We'll be using the -e flag just in case it is actually a symlink to another location.
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# The get_distro function will use short if statements to check for the os-release file existence and readability.
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# Then it will source it and output the distribution's name or exit in case of failure of either case.
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function get_distro {
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if [[ -e /etc/os-release ]] && [[ -r /etc/os-release ]]; then # Check if file exists and is readable
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. /etc/os-release # Source the file
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printf "%s" "$NAME" # Output the distribution's name
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else # If the file does not exist or is not readable
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printf "%s" "File os-release not found or not readable" # Output error message
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exit 1 # Exit with error code 1
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fi
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}
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# The get_package_manager function will take the output of the get_distro function and determine
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# which is the package manager used for the most popular server distros and exit if it is not found.
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function get_package_manager {
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local distro # Declare distro as a local variable
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distro="$(get_distro)" # Get the distribution name
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case "$distro" in # Use case to check for the distribution name
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"Ubuntu" | "Debian GNU/Linux") # If the distribution is Ubuntu or Debian
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printf "%s" "apt" # Output apt
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;;
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"CentOS Linux" | "Fedora" | "Red Hat Enterprise Linux Server") # If the distribution is CentOS, Fedora or RHEL
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printf "%s" "dnf" # Output dnf
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;;
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"openSUSE Leap") # If the distribution is OpenSUSE
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printf "%s" "zypper" # Output zypper
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;;
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*)
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# If the distribution is none of the above, output unsupported distribution
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# and exit with error code 1
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printf "%s" "Unsupported distribution"
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exit 1 # Exit with error code 1
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;;
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esac
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}
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# The install_packages function will take the output of the get_package_manager function and install any
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# package passed as an argument to it. It will also check if the package manager is known and exit if it is not.
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function install_packages {
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local package_manager # Declare package_manager as a local variable
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package_manager="$(get_package_manager)" # Get the package manager
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case "$package_manager" in # Use case to check for the package manager
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"apt") # If the package manager is apt
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sudo apt update # Update the package list
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sudo apt install -y "$@" # Install the packages passed as arguments
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;;
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"dnf") # If the package manager is dnf
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sudo dnf install -y "$@" # Install the packages passed as arguments
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;;
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"zypper") # If the package manager is zypper
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sudo zypper install -y "$@" # Install the packages passed as arguments
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;;
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*)
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# If the package manager is not one of the above, output unsupported package manager
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# and exit with error code 1
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printf "%s" "Unsupported package manager"
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exit 1 # Exit with error code 1
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;;
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esac
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}
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# The check_dependencies function will check if the dependencies defined in a local array are not installed
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# and store the ones that are indeed absent in another local array.
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# Then it will install the packages that are missing by invoking the install_packages function.
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function check_dependencies {
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local dependencies=(curl git sudo vim ssh whiptail) # Declare dependencies as a local array
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#> see what to do with name differences between distros if any <#
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local missing_dependencies=() # Declare missing_dependencies as a local array
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for dependency in "${dependencies[@]}"; do # Loop through the dependencies array
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# If the dependency is not installed, add it to the missing_dependencies array
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! command -v "$dependency" &> /dev/null && missing_dependencies+=("$dependency")
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done
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# If the missing_dependencies array is not empty, install the packages
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[[ ${#missing_dependencies[@]} -ne 0 ]] && install_packages "${missing_dependencies[@]}"
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}
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# The main function will call the check_dependencies function and exit if it fails.
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# It will also output a message to the user to let them know that the script has finished.
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function main {
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check_dependencies || exit 1 # Check dependencies and exit if it fails
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printf "%s" "Script finished" # Output message to the user
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}
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# The am_i_root function will check if the user is root and exit if they are not.
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function am_i_root {
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if [[ $EUID -ne 0 ]]; then # Check if the user is root
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printf "%s" "Please run as root" # Output message to the user
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exit 1 # Exit with error code 1
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fi
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}
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# The getArgs function will get the arguments passed to the script and store them in an array.
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# It will also check if the arguments are valid and exit if they are not.
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function getArgs {
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local args=() # Declare args as a local array
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while [[ $# -gt 0 ]]; do # Loop through the arguments
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case "$*" in # Use case to check for the arguments
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--help | -h) # If the argument is --help or -h
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printf "%s" "Usage: $SCRIPT_NAME [OPTION]..."
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;;
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--create-user | -cu) # If the argument is --create-user or -cu
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args+=("$1") # Add the argument to the args array
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shift # Shift the arguments
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case "$*" in
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--username=* | -u=*) # If the argument is --username=* or -u=*
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args+=("$1") # Add the argument to the args array
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shift # Shift the arguments
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;;
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--password=* | -p=*) # If the argument is --password=* or -p=*
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args+=("$1") # Add the argument to the args array
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shift # Shift the arguments
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;;
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*)
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printf "%s" "Invalid argument: $1"
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exit 1
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;;
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esac
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create_user "${args[@]}" # Call the create_user function with the args array as arguments
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;;
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--harden-ssh | -hs) # If the argument is --harden-ssh or -hs
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args+=("$1") # Add the argument to the args array
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shift # Shift the arguments
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harden_ssh "${args[@]}" # Call the harden_ssh function with the args array as arguments
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;;
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esac
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done
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printf "%s" "${args[@]}" # Output the args array
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}
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# The createUser function will create a new user with the username and password passed as arguments.
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function createUser {
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# Declare username as a local variable and assign it the first argument passed to the function
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local username="$1"
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# Declare password as a local variable and assign it the second argument passed to the function
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local password="$2"
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# Check if the user already exists and exit if they do
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if id -u "$username" &> /dev/null; then
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printf "%s" "User already exists"
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exit 1
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fi
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# Create the user and add them to the sudo group
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useradd -m -G sudo "$username"
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# Set the user's password using printf to avoid the password being echoed to the terminal
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printf "%s" "$username:$password" | chpasswd
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}
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# Global array of the service names to be restarted
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services=()
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# The hardenSSH function will use sed to modify the sshd_config file to have the following settings:
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# - Allow ssh access to users in the sudo group only
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# - Change the port to 22121 if it is available
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# - Configure idle timeout to 5 minutes
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# - Limit the number of authentication attempts to 3
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# - Disable root login
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# - Disable empty passwords
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# - Disable ssh protocol 1
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# - Disable password authentication and only allow public key authentication
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# - Disable X11 forwarding for security reasons (X11 forwarding is not needed for ssh)
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# - Disable agent forwarding to prevent ssh-agent hijacking
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# Then it will store the sshd service name in the services array.
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function hardenSSH {
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# Check if the sshd_config file exists and is readable
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# If it is, then modify it using sed and restart the sshd service
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# If it is not, then output an error message and exit with error code 1
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# The -i flag is used to modify the file in place
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# We split the sed command into multiple lines for readability purposes
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# and to avoid calling it multiple times
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if [[ -e /etc/ssh/sshd_config ]] && [[ -r /etc/ssh/sshd_config ]]; then
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sed -i \
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-e 's/^#AllowGroups.*/AllowGroups sudo/' \
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-e 's/^#Port.*/Port 22121/' \
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-e 's/^#ClientAliveInterval.*/ClientAliveInterval 300/' \
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-e 's/^#ClientAliveCountMax.*/ClientAliveCountMax 3/' \
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-e 's/^#PermitRootLogin.*/PermitRootLogin no/' \
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-e 's/^#PermitEmptyPasswords.*/PermitEmptyPasswords no/' \
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-e 's/^#Protocol.*/Protocol 2/' \
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-e 's/^#PasswordAuthentication.*/PasswordAuthentication no/' \
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-e 's/^#X11Forwarding.*/X11Forwarding no/' \
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-e 's/^#AllowAgentForwarding.*/AllowAgentForwarding no/' \
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/etc/ssh/sshd_config
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services+=("sshd") # Add sshd to the services array
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else
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printf "%s" "File sshd_config not found or not readable"
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exit 1
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fi
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}
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# Call the main function
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main
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am_i_root
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exit 0 # The right and proper way to exit a script
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