Generate knockd configuration file

knockd_generator.sh

#!/bin/bash

PINS=$1
HOSTNAME=$2
USERNAME=$3

PINDIPS=`shuf -i 1024-65534 -n $PINS`
OUTLOCK="knockd.conf"

# CHECK SYNTAX
if [ "$#" -ne 3 ]; then
    echo "Syntax Error!"
    echo "Syntax: $0 <number of pins> <hostname/ip> <username to login>"
    exit
fi

# CREATE FILES
touch $OUTLOCK

# GENERATE SERVER CONFIGURATION
echo "GENERATING KNOCKd CONFIG FILE"
echo "copy knockd.conf to /etc/knockd.conf"
echo "[option]" > $OUTLOCK
echo "   UseSyslog" >> $OUTLOCK
echo "" >> $OUTLOCK
echo "[KnockSSH]" >> $OUTLOCK
for x in `seq 1 $PINS`
do
    PIN=$(echo $PINDIPS | cut -d " " -f $x)
    SEQUENCE="$SEQUENCE,$PIN"
done
SEQUENCE=$(echo $SEQUENCE | sed -r 's/^.{1}//')
echo "   sequence = $SEQUENCE" >> $OUTLOCK
echo "   tcpflags = syn" >> $OUTLOCK
echo "   seq_timeout = 15" >> $OUTLOCK
echo "   start_command = /sbin/iptables -I INPUT -s %IP% -p tcp --dport 22 -j ACCEPT" >> $OUTLOCK
echo "   cmd_timeout = 10" >> $OUTLOCK
echo "   stop_command = /sbin/iptables -D INPUT -s %IP% -p tcp --dport 22 -j ACCEPT" >> $OUTLOCK
echo "" >> $OUTLOCK

echo " "

# GENERATE SERVER ACCESS COMMAND
SEQUENCE=$(echo $SEQUENCE | sed -r 's/,/ /g')
echo "USE THE COMMAND BELLOW TO OPEN THE WINDOW AND ACCESS THE SERVER:"
echo " "
echo "for x in $SEQUENCE; do nmap -Pn --host_timeout 201 --max-retries 0 -p "'$x'" $HOSTNAME; done
&& ssh $USERNAME@$HOSTNAME"