floatingssh.sh

#!/bin/bash
#Please make sure that this script is stored in '/usr/local/bin/fssh/'
#Otherwise you will run into problems with the execution of it
#
#Sourcing all the variables from the /etc/fssh/FSSH_config.sh file
source <(grep -E '^\w+=' /etc/fssh/FSSH_config.sh)


#Randomly generating a new SSH Port number between 1024 and 32767
new_port=$((1024 + $RANDOM % 32767))

#Current Port Detection
old_port=$(sudo netstat -tulpan | grep sshd | cut -d ":" -f 2 | cut -d " " -f 1 | head -1)

#Checking if newly generated Port Number is already being used 
#If this is positive a new Number will be generated and the old Port will be updated
port_used=$(sudo netstat -tulpan | grep ":$new_port") 

if [ "$port_used" == "" ];
then 


#UPDATING /ETC/SSH/SSHD_CONFIG
sudo sed -i "s/Port $old_port/Port $new_port/" /etc/ssh/sshd_config

#
#
#MYSQL DB UPDATE
#Parsing new SSH port to Mysql database that is configured in /etc/floatingssh/fssh.conf
sudo mysql -u $db_user --password="$password" << EOF

USE $db_name;

DELETE FROM sshports WHERE host = '$host_ip';
INSERT INTO sshports ( host, portnum, date) VALUES ( '$host_ip', '$new_port', '2023-05-18');

EOF
###

else

#GENERATING NEW PORT NUMBER
new_port=$((1024 + $RANDOM % 32767))

###############UPDATING /ETC/SSH/SSHD_CONFIG
sed -i "s/Port $old_port/Port $new_port/" /etc/ssh/sshd_config
#
#
#
#MYSQL DB UPDATE
#Parsing new SSH port to Mysql database that is configured in /etc/floatingssh/fssh.conf
sudo mysql -u $db_user --password="$password" << EOF

USE $db_name;

DELETE FROM sshports WHERE host = '$host_ip';
INSERT INTO sshports ( host, portnum, date) VALUES ( '$host_ip', '$new_port', '2023-05-18');

EOF
###

fi

#ADDING AND REMOVING FIREWALL RULES
sudo ufw delete allow $old_port
sudo ufw allow $new_port
sudo ufw status | grep $new_port

#RESTARTING SSHD TO APPLY NEW PORT CHANGE
sudo systemctl restart sshd