460 lines
14 KiB
Bash
460 lines
14 KiB
Bash
#!/etc/bin/env bash
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# Accept user name as a script argument
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# If no username provided
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# generate a random username - all lowercase
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# Something important fails
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# Revert everything back to how it was
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# Redirect every output to a logfile
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# Ask the user to NOT logout yet
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# Ask him to report back if he can login using the new user -with the ssh-private key
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# If not
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# Remove the SSH-only login and ask the user to login using password
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# If he can - great - tell him to talk to the server provider's support to get help regarding SSH-only access
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# Report the things
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# Root password
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# User Password
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# User SSH-Private Key
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# User SSH-Public key
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# Display the root-user's new password on screen
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# What to do if making .bkp file fails?
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##############################################################
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# Basic checks before starting
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##############################################################
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# No root - no good
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[ "$(id -u)" != "0" ] && {
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echo "Error: You must be root to run this script, please login as root and execute the script again."
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exit 1
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}
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# Check supported OSes
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if [[ $(sed 's/\..*//' /etc/debian_version) -eq 8 ]]; then
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DEB_VER_STR="jessie"
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elif [[ $(sed 's/\..*//' /etc/debian_version) -eq 9 ]]; then
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DEB_VER_STR="stretch"
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else
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printf "This version of Debian is NOT supported.\\n"
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exit 1
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fi
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##############################################################
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# Display what the script does
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##############################################################
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# What to do if something fails
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# Catastophic failure
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# Ignorable failure
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# Where to find the log file
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##############################################################
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# Gather info
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##############################################################
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# Change root user's password
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# Choose a user name
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clear
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echo "Do you want to change root password ? (y/n)"
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echo "(You might want to do this if you received it as an email from your host.)"
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while [[ $RESET_ROOT_PWD != "y" && $RESET_ROOT_PWD != "n" ]]; do
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read -rp "Select an option [1-2]: " RESET_ROOT_PWD
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done
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# Ask for a user name
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echo ""
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echo "A new non-root user will be created for you."
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read -rp "Please provide a user name - " NORM_USER_NAME
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# If the user exists - ask for a different username
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while [[ ! "$NORM_USER_NAME" ]] && [[ $(getent passwd "$NORM_USER_NAME" | wc -l) -gt 0 ]]; do
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echo "User name either already exists or you provided an invalid username."
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read -rp "Please provide a user name - " NORM_USER_NAME
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done
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##############################################################
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# Log
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##############################################################
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CSI='\033['
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CEND="${CSI}0m"
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CRED="${CSI}1;31m"
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CGREEN="${CSI}1;32m"
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CVERTICAL="|"
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CHORIZONTAL="_"
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SCRIPT_NAME=server_harden
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SCRIPT_VERSION=0.2
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LOGFILE=/tmp/"$SCRIPT_NAME"_v"$SCRIPT_VERSION".log
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function horizontal_fill() {
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local char=$1
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declare -i rep=$2
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for ((x = 0; x < "$rep"; x++)); do
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printf %s "$char"
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done
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}
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function line_fill() {
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horizontal_fill "$1" "$2"
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printf "\\n"
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}
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function recap (){
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local purpose=$1
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local value=$2
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if [[ $value ]]; then
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value="[${CGREEN}${value}${CEND}]"
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else
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value="${CRED}-FAILED-${CEND}"
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fi
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horizontal_fill "$CVERTICAL" 1
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printf "%20s:%5s%-33s" "$purpose" " " "$(echo -e "$value")"
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line_fill "$CVERTICAL" 1
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}
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function finally(){
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#local what_failed=$1
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line_fill "$CHORIZONTAL" 60
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recap "New root Password" "$PASS_ROOT"
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recap "User Name" "$NORM_USER_NAME"
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recap "User's Password" "$USER_PASS"
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recap "User's SSH Private Key Location" "$KEY_PASS"
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recap "User's SSH Public Key Location" "$KEY_PASS"
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recap "User's SSH Key Passphrase" "$KEY_PASS"
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line_fill "$CHORIZONTAL" 60
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}
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function log() {
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local EVENT=$1
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local RESULT=$2
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if [ "$RESULT" = "SUCCESSFUL" ]
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then
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printf "%30s %7s [${CGREEN}${RESULT}${CEND}]\\n" "$EVENT" " "
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echo "$(date '+%Y-%m-%d %H:%M:%S')" - "$EVENT" - "$RESULT" >> "$LOGFILE"
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elif [ "$RESULT" = "FAILED" ]
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then
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printf "%30s %7s [${CRED}${RESULT}${CEND}]\\n" "$EVENT" " "
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printf "\\n\\nPlease look at %s\\n\\n" "$LOGFILE"
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echo "$(date '+%Y-%m-%d %H:%M:%S')" - "$EVENT" - "$RESULT" >> "$LOGFILE"
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else
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printf "%30s %7s [${CRED}..${CEND}]\\r" "$EVENT" " "
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echo "$(date '+%Y-%m-%d %H:%M:%S')" - "$EVENT" - "begin..." >> "$LOGFILE"
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fi
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}
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declare SESSION_TYPE=""
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# Check if the user connected through SSH
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if [[ -n "$SSH_CLIENT" ]] || [[ -n "$SSH_TTY" ]]; then
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SESSION_TYPE=remote/ssh
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else
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case $(ps -o comm= -p $PPID) in
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sshd|*/sshd)
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SESSION_TYPE=remote/ssh;
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esac
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fi
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if [[ $SESSION_TYPE == "remote/ssh" ]]; then
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printf "You are currently connected to an SSH session.\\n"
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else
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printf "You are currently connected using password authentication.\\n"
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fi
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##############################################################
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# Change root's password
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##############################################################
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if [[ $RESET_ROOT_PWD == 'y' ]]; then
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{
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log "Changing root password"
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# Generate a 15 character random password
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PASS_ROOT="$(< /dev/urandom tr -cd "[:alnum:]" | head -c 15)" || exit 1
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# Change root's password
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echo -e "${PASS_ROOT}\\n${PASS_ROOT}" | passwd > /dev/null
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}
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if [[ $? -eq 0 ]]; then
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log "Changing root password" "SUCCESSFUL"
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else
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# Low priority - since we are disabling root login anyways
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log "Changing root password" "FAILED"
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fi
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fi
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##############################################################
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# Create a normal user
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##############################################################
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{
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log "Creating new user"
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# Generate a 15 character random password
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USER_PASS="$(< /dev/urandom tr -cd "[:alnum:]" | head -c 15)" || exit 1
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# Create the user and assign the above password
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echo -e "${USER_PASS}\\n${USER_PASS}" | adduser "$NORM_USER_NAME" -q --gecos "First Last,RoomNumber,WorkPhone,HomePhone" 2> /dev/null
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# Give root privilages to the above user
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usermod -aG sudo "$NORM_USER_NAME" || exit 1
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}
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if [[ $? -eq 0 ]]; then
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log "Creating new user" "SUCCESSFUL"
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else
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log "Creating new user" "FAILED"
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finally "CNU"
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exit 1;
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fi
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##############################################################
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# Create SSH Key for the new user
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##############################################################
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{
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log "Creating SSH Key for new user"
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shopt -s nullglob
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KEY_FILES=("$SSH_DIR"/"$NORM_USER_NAME".pem*)
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# Create key file only if it does NOT exist
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if [[ ! ${KEY_FILES[0]} ]]; then
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SSH_DIR=/home/"$NORM_USER_NAME"/.ssh
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mkdir "$SSH_DIR" || exit 1
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# Generate a 15 character random password for key
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KEY_PASS="$(< /dev/urandom tr -cd "[:alnum:]" | head -c 15)" || exit 1
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# Create a OpenSSH-compliant ed25519-type key
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ssh-keygen -a 1000 -o -t ed25519 -N "$KEY_PASS" -C "$NORM_USER_NAME" -f "$SSH_DIR"/"$NORM_USER_NAME".pem -q || exit 1
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KEY_FILES=("$SSH_DIR"/"$NORM_USER_NAME".pem*)
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fi
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}
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if [[ $? -eq 0 ]]; then
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log "Creating SSH Key for new user" "SUCCESSFUL"
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else
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log "Creating SSH Key for new user" "FAILED"
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finally "CSK"
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exit 1;
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fi
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##############################################################
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# Add generated key to authorized_keys file
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##############################################################
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{
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log "Adding SSH Key to 'authorized_keys' file"
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# Insert the public key into "authoried_keys" file
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cat "${KEY_FILES[1]}" >> "$SSH_DIR"/authorized_keys || exit 1
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}
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if [[ $? -eq 0 ]]; then
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log "Adding SSH Key to 'authorized_keys' file" "SUCCESSFUL"
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else
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log "Adding SSH Key to 'authorized_keys' file" "FAILED"
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finally "ATAF"
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exit 1;
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fi
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##############################################################
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# Secure authorized_keys file
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##############################################################
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{
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log "Securing 'authorized_keys' file"
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# Set appropriate permissions for ".ssh" dir and "authorized_key" file
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chown -R "$NORM_USER_NAME" "$SSH_DIR" && \
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chgrp -R "$NORM_USER_NAME" "$SSH_DIR" && \
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chmod 700 "$SSH_DIR" && \
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chmod 400 "$SSH_DIR"/authorized_keys && \
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chattr +i "$SSH_DIR"/authorized_keys
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}
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if [[ $? -eq 0 ]]; then
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log "Securing 'authorized_keys' file" "SUCCESSFUL"
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else
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log "Securing 'authorized_keys' file" "FAILED"
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fi
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##############################################################
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# Enable SSH-only login
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##############################################################
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function config_search_regex(){
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local search_key=$1
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declare -i isCommented=$2
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local value=$3
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if [[ "$isCommented" -eq 1 ]] && [[ ! "$value" ]]; then
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# Search Regex for an uncommented (active) field
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echo '(^ *)'"$search_key"'( *).*([[:word:]]+)( *)$'
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elif [[ "$isCommented" -eq 2 ]] && [[ ! "$value" ]]; then
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# Search Regex for a commented out field
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echo '(^ *)#.*'"$search_key"'( *).*([[:word:]]+)( *)$'
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elif [[ "$isCommented" -eq 1 ]] && [[ "$value" ]]; then
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# Search Regex for an active field with specified value
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echo '(^ *)'"$search_key"'( *)('"$value"')( *)$'
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elif [[ "$isCommented" -eq 2 ]] && [[ "$value" ]]; then
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# Search Regex for an commented (inactive) field with specified value
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echo '(^ *)#.*'"$search_key"'( *)('"$value"')( *)$'
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else
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exit 1
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fi
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}
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function set_config_key(){
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local file_location=$1
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local key=$2
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local value=$3
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ACTIVE_KEYS_REGEX=$(config_search_regex "$key" "1")
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ACTIVE_CORRECT_KEYS_REGEX=$(config_search_regex "$key" "1" "$value")
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INACTIVE_KEYS_REGEX=$(config_search_regex "$key" "2")
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# If no keys present - insert the correct key to the end of the file
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if [[ $(grep -Pnc "$INACTIVE_KEYS_REGEX" "$file_location") -eq 0 ]] && [[ $(grep -Pnc "$ACTIVE_KEYS_REGEX" "$file_location") -eq 0 ]];
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then
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echo "$key" "$value" >> "$file_location"
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fi
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# If Config file already has active keys
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# Keep only the LAST correct one and comment out the rest
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if [[ $(grep -Pnc "$ACTIVE_KEYS_REGEX" "$file_location") -gt 0 ]];
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then
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# Last correct active entry's line number
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LAST_CORRECT_LINE=$(grep -Pn "$ACTIVE_CORRECT_KEYS_REGEX" "$file_location" | tail -1 | cut -d: -f 1)
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# Loop through each of the active lines
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grep -Pn "$ACTIVE_KEYS_REGEX" "$file_location" | while read -r i;
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do
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# Get the line number
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LINE_NUMBER=$(echo "$i" | cut -d: -f 1 )
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# If this is the last correct entry - break
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if [[ $LAST_CORRECT_LINE -ne 0 ]] && [[ $LINE_NUMBER == "$LAST_CORRECT_LINE" ]]; then
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break
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fi
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# Comment out the line
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sed -i "$LINE_NUMBER"'s/.*/#&/' "$file_location"
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done
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fi
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# If Config file has inactive keys and NO active keys
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# Append the appropriate key below the LAST inactive key
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if [[ $(grep -Pnc "$INACTIVE_KEYS_REGEX" "$file_location") -gt 0 ]] && [[ $(grep -Pnc "$ACTIVE_KEYS_REGEX" "$file_location") -eq 0 ]];
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then
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# Get the line number of - last inactive key
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LINE_NUMBER=$(grep -Pn "$INACTIVE_KEYS_REGEX" "$file_location" | tail -1 | cut -d: -f 1)
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(( LINE_NUMBER++ ))
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# Insert the correct setting below the last inactive key
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sed -i "$LINE_NUMBER"'i'"$key"' '"$value" "$file_location"
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fi
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}
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{
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log "Enabling SSH-only login"
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# Backup the sshd_config file
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cp /etc/ssh/sshd_config /etc/ssh/sshd_config.bak || exit 1
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# Remove root login
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set_config_key "/etc/ssh/sshd_config" "PermitRootLogin" "no"
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# Disable password login
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set_config_key "/etc/ssh/sshd_config" "PasswordAuthentication" "no"
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# Set SSH Authorization-Keys path
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set_config_key "/etc/ssh/sshd_config" "AuthorizedKeysFile" '%h\/\.ssh\/authorized_keys'
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systemctl restart sshd
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}
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if [[ $? -eq 0 ]]; then
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log "Enabling SSH-only login" "SUCCESSFUL"
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else
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log "Enabling SSH-only login" "FAILED"
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finally "ESOL"
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exit 1;
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fi
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##############################################################
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# Change default source-list
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##############################################################
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# Low priority - But what to do if it fails???
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log "Changing urls in sources.list to defaults"
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mv /etc/apt/sources.list /etc/apt/sources.list.bak
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sed -i "1,$(wc -l < /etc/apt/sources.list.bak) s/^/#/" /etc/apt/sources.list.bak
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# Default sources list for debian
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cat <<TAG > /etc/apt/sources.list || exit 1
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deb https://deb.debian.org/debian ${DEB_VER_STR} main
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deb-src https://deb.debian.org/debian ${DEB_VER_STR} main
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## Major bug fix updates produced after the final release of the
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## distribution.
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deb http://security.debian.org ${DEB_VER_STR}/updates main
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deb-src http://security.debian.org ${DEB_VER_STR}/updates main
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deb https://deb.debian.org/debian ${DEB_VER_STR}-updates main
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deb-src https://deb.debian.org/debian ${DEB_VER_STR}-updates main
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deb https://deb.debian.org/debian ${DEB_VER_STR}-backports main
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deb-src https://deb.debian.org/debian ${DEB_VER_STR}-backports main
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TAG
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# Find any additional sources listed by the provider and comment them out
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SOURCE_FILES=(/etc/apt/source*/*.list)
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if [[ ${#SOURCE_FILES[@]} -gt 0 ]]; then
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for file in "${SOURCE_FILES[@]}";
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do
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mv "$file" "$file".bak
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sed -i "1,$(wc -l < "$file") s/^/#/" "$file" >&2 /dev/null
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done
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fi
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# Comment out cloud-init generated templates for sources
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CLOUD_INIT_FILES=(/etc/cloud/templates*/*.tmpl)
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if [[ ${#CLOUD_INIT_FILES[@]} -gt 0 ]]; then
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for file in "${CLOUD_INIT_FILES[@]}";
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do
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mv "$file" "$file".bak
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sed -i "1,$(wc -l < "$file") s/^/#/" "$file" >&2 /dev/null
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done
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fi
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if [[ $? -eq 0 ]]; then
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log "Changing urls in sources.list to defaults" "FAILED"
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else
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log "Changing urls in sources.list to defaults" "FAILED"
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fi
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##############################################################
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# Install required softwares
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##############################################################
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apt-get update && apt-get upgrade -y && apt-get install -y sudo curl screen
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##############################################################
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# Recap
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##############################################################
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finally |