#!/bin/bash
# brezular v0.1

function show_choices {
 echo -e "\n*** Script configures pppoe connection, select from options below ***\n"
 echo -e "a) Change pppoe username"
 echo -e "b) Change pppoe password"
 echo -e "c) Enable pppoe"
 echo -e "d) Disable pppoe"
 echo -e "q) Quit script\n"
}

function get_credentials {
 user="$(cat /etc/ppp/chap-secrets | awk '{print $1}')"
 id="$(cat /etc/ppp/chap-secrets | awk '{print $2}')"
 pass="$(cat /etc/ppp/chap-secrets | awk '{print $3}')"
}

function change_nat {
    /usr/local/sbin/iptables -t nat -F
    /usr/local/sbin/iptables --table nat -A POSTROUTING -o "$1" --jump MASQUERADE
    /usr/local/sbin/iptables-save > /usr/local/etc/iptables/iptables.rules
}


uid="$UID"
[ "$uid" != 0 ] && echo -e "\nRun '$0' as root, exiting" && exit 1

while true; do
 show_choices
 read val
 case $val in
    a)
       get_credentials
       echo -en "\nEnter pppoe username: "
       read newuser
       echo "$newuser $id $pass" > /etc/ppp/chap-secrets
       sed -i "s/$user/$newuser/g" /etc/ppp/peers/my_ISP
       echo -e "\n*** Username successfully changed ***"
       /usr/bin/filetool.sh -b 1>/dev/null
       ;;
    b)
       get_credentials
       echo -en "\nEnter pppoe password: "
       read newpass
       echo "$user $id $newpass" > /etc/ppp/chap-secrets
       echo -e "\n*** Password successfully changed ***"
       /usr/bin/filetool.sh -b 1>/dev/null
       ;;
    c)
       ### Enable pppoe ####
       grep -q "^/usr/local/sbin/pppd" /opt/bootsync.sh
       if [ "$?" == 0 ]; then                                      # pppd configured to run after boot
          ps -ef | grep pppd | grep -v grep 1>/dev/null            # check if pppd is running
          if [ "$?" == 1 ]; then                                     # pppd daemon isn't  running 
             /usr/local/sbin/pppd call my_ISP &>/dev/null            # start pppd daemon
             ps -ef | grep pppd | grep -v grep 1>/dev/null            # check if we started pppd 
             if [ "$?" == 0 ]; then                                
                echo -e "\n*** pppoe successfully started ****"
             else
                echo -e "\n*** pppoe cannot be started, reboot router ****"
             fi
          fi
       else                                                                                 # pppd is disabled to run after boot                                             
          sed -i "s/#\/usr\/local\/sbin\/pppd/\/usr\/local\/sbin\/pppd/g" /opt/bootsync.sh   # enable pppd after boot
          change_nat ppp0                                                                    # NAT LAN behind ppp0
          ps -ef | grep pppd | grep -v grep 1>/dev/null                                      # check if pppd is running                         
          if [ "$?" == 1 ]; then                                                              # no pppd daemon is running     
             /usr/local/sbin/pppd call my_ISP &>/dev/null                                     # so we will start it                             
          elif [ "$?" == 0 ]; then                                                          # old pppd daemon is running 
             pppdpid="$(ps -ef | grep pppd | grep -v grep | awk '{print $1}')"                # we get its pid and kill it
             kill -9 $pppdpid                                                
             /usr/local/sbin/pppd call my_ISP 1>/dev/null                                   # restat ppp daemon
          fi            
          echo -e "\n*** pppoe successfully enabled, reboot router ***"
          /usr/bin/filetool.sh -b 1>/dev/null
       fi
       ;; 
    d)
       ### Disable pppoe ###
       grep -q "^#/usr/local/sbin/pppd" /opt/bootsync.sh                          
       if [ "$?" == 1 ]; then                                                              # pppd is disabled after start
          sed -i "s/\/usr\/local\/sbin\/pppd/#\/usr\/local\/sbin\/pppd/g" /opt/bootsync.sh # so we have to disable it
          change_nat eth0                                                                  # change NAT back from ppp0 to eth0
       fi
       ps -ef | grep pppd | grep -v grep 1>/dev/null                                       # check if pppd is running                                      
       if [ "$?" == 0 ]; then                                                              # pppd  daemon is running
          pppdpid="$(ps -ef | grep pppd | grep -v grep | awk '{print $1}')"                # we get its pid and kill it                                    
          kill -9 $pppdpid                                                                                                              
       fi                          
       echo -e "\n*** pppoe successfully disabled, reboot router ***"                                  
       /usr/bin/filetool.sh -b 1>/dev/null                                             
       ;;   
    q)                        
       exit 0            
       ;;      
    *)
       echo -e "\n*** Please, enter valid option ***"
       ;;
 esac
done