Basic firewall only block incoming access

basic_firewall.sh

#!/bin/bash
# My system IP/set ip address of server
PUBLIC_PORT=(22 80)

# comment this to disable
ENABLE_PRIVATE=1

##
# $PRIVATE_PORT must have the same array lenght
# with PRIVATE_IP
##
PRIVATE_PORT=( \
                8080 \
                9100 \
                9113 \
            )

PRIVATE_IP=( \
            "192.168.1.24" \
            "192.168.1.24" \
            "192.168.1.24" \
        )

flush_firewall() {
    sudo iptables -P INPUT ACCEPT
    sudo iptables -P FORWARD ACCEPT
    sudo iptables -P OUTPUT ACCEPT
    sudo iptables -t nat -F
    sudo iptables -t mangle -F
    sudo iptables -F
    sudo iptables -X
}

# Setting default filter policy
drop_firewall() {
    sudo iptables -P INPUT DROP
    sudo iptables -P FORWARD DROP
}
# Allow unlimited traffic on loopback
allow_loopback() {
    sudo iptables -A INPUT -i lo -j ACCEPT
    sudo iptables -A OUTPUT -o lo -j ACCEPT
}

# Allow port for all
allow_public() {
    for PORT in ${PUBLIC_PORT[@]}; do
        sudo iptables -A INPUT -p tcp --dport $PORT -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT
        echo "Port ${PORT}  Opened."
    done
}

# Allow port base on source ip
allow_private() {
    for i in ${!PRIVATE_PORT[@]}; do
        sudo iptables -A INPUT -s ${PRIVATE_IP[$i]} -p tcp --dport ${PRIVATE_PORT[$i]} -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT
        echo "${PRIVATE_IP[$i]} ${PRIVATE_PORT[$i]} Opened."
    done
}

flush_firewall
allow_loopback

sudo iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT 
allow_public
[ $ENABLE_PRIVATE ] && allow_private