#!/bin/bash

echo 'Enter the hostname(example gate):'
read HOSTNAME
echo 'Enter the domain(example corp1.un):'
read DOMAIN
echo 'Enter the fourth octet of the external ip address(example 31):'
read EXTERNAL_OCTET

echo "$HOSTNAME.$DOMAIN" > /etc/hostname

echo "127.0.0.1 localhost

127.0.1.1 $HOSTNAME.$DOMAIN $HOSTNAME" > /etc/hosts

echo "# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface

auto enp0s8
iface enp0s8 inet static
      address 192.168.1.$EXTERNAL_OCTET/24
      gateway 192.168.1.1

auto enp0s3
iface enp0s3 inet static
      address 172.16.1.1/24" > /etc/network/interfaces

apt update&&apt install isc-dhcp-server sed vim -y
systemctl stop isc-dhcp-server

sed -i'' 's/^INTERFACESv4=""/INTERFACESv4="enp0s3"/g' /etc/default/isc-dhcp-server
sed -i'' 's/^INTERFACESv6=""/#INTERFACESv6=""/g' /etc/default/isc-dhcp-server

echo "ddns-update-style none;
log-facility local7;
authoritative;

default-lease-time 600;
max-lease-time 7200;

option domain-name \"$DOMAIN\";
option domain-name-servers 172.16.1.1;

shared-network LAN1 {
      subnet 172.16.1.0 netmask 255.255.255.0 {
      range 172.16.1.101 172.16.1.254;
      option routers 172.16.1.1;
  }
}" > /etc/dhcp/dhcpd.conf

DEBIAN_FRONTEND=noninteractive apt install iptables iptables-persistent -y

sed -i'' 's/^#net.ipv4.ip_forward=*/net.ipv4.ip_forward=/g' /etc/sysctl.conf
sysctl -f
iptables -t nat -A POSTROUTING -o enp0s8 -s 172.16.1.0/24 -j MASQUERADE
iptables -t nat -A PREROUTING -i enp0s8 --destination 192.168.1.0/24 -p tcp --dport 80 -j DNAT --to-destination 172.16.1.2:80
iptables -t nat -A PREROUTING -i enp0s8 --destination 192.168.1.0/24 -p tcp --dport 443 -j DNAT --to-destination 172.16.1.2:443
iptables -t nat -A PREROUTING -i enp0s8 --destination 192.168.1.0/24 -p tcp --dport 25 -j DNAT --to-destination 172.16.1.2:25
iptables-save > /etc/iptables/rules.v4

apt install bind9 -y

sed -i'' '13,$s/?*\/.*forwarders/forwarders/g' /etc/bind/named.conf.options
sed -i'' 's/?*\/.*0.0.0.0/\t192.168.1.1/' /etc/bind/named.conf.options
sed -i'' 's/?*\/.*};/};/' /etc/bind/named.conf.options
sed -i'' '16a\ \ \ \ \ \ allow-recursion { 192.168.1\/24; 172.16.1\/24; 127\/8; };' /etc/bind/named.conf.options
sed -i'' 's/dnssec-validation auto;/dnssec-validation no;/' /etc/bind/named.conf.options
sed -i'' 's/any/::/' /etc/bind/named.conf.options

echo '$TTL 3h
@ IN SOA ns admin 2024012801 1d 12h 1w 3h
          NS ns
          A 172.16.1.2
          MX 9 mx

ns          IN A 172.16.1.1
gate       IN A 172.16.1.1
server    IN A 172.16.1.2
mx         IN A 172.16.1.2
www      IN A 172.16.1.2' > /etc/bind/$DOMAIN

echo "\$TTL 3h
@ IN SOA ns admin 2024012801 1d 12h 1w 3h
          NS ns
          A 192.168.1.$EXTERNAL_OCTET
          MX 9 mx

ns       IN A 192.168.1.$EXTERNAL_OCTET
mx      IN A 192.168.1.$EXTERNAL_OCTET

www   CNAME ns" > /etc/bind/$DOMAIN.out

echo "zone \"$DOMAIN\" {
         type master;
         file \"/etc/bind/$DOMAIN\";
};" >> /etc/bind/named.conf.local

sed -i'' '9,$d' /etc/bind/named.conf
echo "include \"/etc/bind/named.conf.options\";

view \"inside\" {
           match-clients {
           172.16.1/24;
           127/8;
      };
      include \"/etc/bind/named.conf.local\";
      include \"/etc/bind/named.conf.default-zones\";
};

view \"outside\" {
        zone \"$DOMAIN\" {
           type master;
           file \"/etc/bind/$DOMAIN.out\";
      };
};" >> /etc/bind/named.conf

named-checkconf -z
rndc reload

echo "search $DOMAIN
nameserver 127.0.0.1" > /etc/resolv.conf

init 6