Open/close port shell script

Question

I found a script that allows you to open or close any port and save it to the iptables. The problem I am having is it throws a syntax error after I tell it to close, but before I can give it a port number. The issue is right before the first else.

#!/bin/bash

PATH=/usr/local/bin:/usr/bin:/bin:/usr/local/sbin:/usr/sbin:/sbin

clear

echo -e "############################nnnPresent ports opened on this machine are

$(iptables -nL INPUT | grep ACCEPT | grep dpt)

nCompleted listing...nnn#########################"

read -p "To open port enter open, to close etner close) " OPT1

if [[ "$OPT1" == open ]]

then

read -p "Please enter your desired port number to open: " PORT1

 if [[ "$PORT1" =~ [0-9]{1,6} ]]

 then

iptables -D INPUT $(iptables -nL INPUT --line-numbers | grep "$PORT1" | grep REJECT | awk '{print $1}')

 iptables -A INPUT -m tcp -p tcp --dport "$PORT1" -j ACCEPT && { service iptables save;service iptables restart; echo -e "Ports opend through iptables are n$(iptables -nL INPUT | grep ACCEPT | grep dpt)"; }

 else

 echo "Please enter a valid port(0-65000)"

 fi

elif [[ "$OPT1" == close ]]

then

read -p "Please enter your desired port number to close: " PORT1

        if [[ "$PORT1" =~ [0-9]{1,6} ]]

        then

 iptables -D INPUT $(iptables -nL INPUT --line-numbers | grep "$PORT1" | grep ACCEPT | awk '{print $1}')

        iptables -A INPUT -m tcp -p tcp --dport "$PORT1" -j REJECT && { service iptables save;service iptables restart; echo -e "Ports closed through iptables are n$(iptables -nL INPUT | grep REJECT | grep dpt)"; }

        else

        echo "Please enter a valid port(0-65000)"

        fi

else

echo "Please enter only open or close..! Exiting script now";exit 1

fi

Answer 1

I don't see any error in the script. Can you paste the error that you are getting? See below

[root@kali ~]# ./ip.sh

######################nnnPresent ports opened on this machine are

nCompleted listing...nnn#########################

To open port enter open, to close etner close) close

Please enter your desired port number to close: 23

iptables: Bad rule (does a matching rule exist in that chain?).

iptables: Saving firewall rules to /etc/sysconfig/iptables:[ OK ]

Redirecting to /bin/systemctl restart iptables.service

Ports closed through iptables are nREJECT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:23 reject-with icmp-port-unreachable