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#!/bin/bash
# $Id: alcasar-watchdog.sh 2887 2020-11-26 22:08:42Z rexy $
# alcasar-watchdog.sh
# by Rexy
# This script is distributed under the Gnu General Public License (GPL)
# - Ce script prévient les usagers de l'indisponibilité de l'accès Internet
# - Il déconnecte les usagers dont les équipements réseau ne répondent plus (leur onglet 'status.php' a été fermé)
# - Il deconnecte les usagers dont les adresses MAC sont usurpées
#
# - This script tells users that Internet access is down
# - It logs out users whose PCs are quiet (their status tab is closed)
# - It logs out users whose MAC address is used by other systems (usurped)
CONF_FILE="/usr/local/etc/alcasar.conf"
EXTIF=`grep ^EXTIF= $CONF_FILE|cut -d"=" -f2` # EXTernal InterFace
INTIF=`grep ^INTIF= $CONF_FILE|cut -d"=" -f2` # INTernal InterFace
private_ip_mask=`grep ^PRIVATE_IP= $CONF_FILE|cut -d"=" -f2`
private_ip_mask=${private_ip_mask:=192.168.182.1/24}
PRIVATE_IP=`echo $private_ip_mask |cut -d"/" -f1`
PRIVATE_IP=${PRIVATE_IP:=192.168.182.1}
current_users_file="/tmp/current_users.txt" # file containing active users with their "status.php" tab open
DIR_WEB="/var/www/html"
Index_Page="$DIR_WEB/index.php"
IPTABLES="/sbin/iptables"
TUNIF="tun0" # listen device for chilli daemon
OLDIFS=$IFS
IFS=$'\n'
function lan_down_alert ()
# users are redirected on ALCASAR IP address if a LAN problem is detected
{
case $LAN_DOWN in
"1")
logger -t alcasar-watchdog "$EXTIF (WAN card) link down"
echo "$EXTIF (WAN card) link down"
/bin/sed -i "s?diagnostic =.*?diagnostic = \"$EXTIF (WAN card) link down\";?g" $Index_Page
;;
"2")
logger -t alcasar-watchdog "can't contact the default router"
echo "can't contact the default router"
/bin/sed -i "s?diagnostic =.*?diagnostic = \"can't contact the default router\";?g" $Index_Page
;;
"3")
logger -t alcasar-watchdog "can't resolv DNS queries"
echo "can't resolv DNS queries"
/bin/sed -i "s?diagnostic =.*?diagnostic = \"can't resolv DNS queries\";?g" $Index_Page
;;
esac
net_pb=`grep "network_pb = true;" $Index_Page|wc -l`
if [ $net_pb = "0" ] # user alert (only the first time)
then
/bin/sed -i "s?^\$network_pb.*?\$network_pb = true;?g" $Index_Page
$IPTABLES -I PREROUTING -t nat -i $TUNIF -p udp --dport domain -j REDIRECT --to-port 56
fi
}
function lan_test ()
# LAN connectiivity testing
{
watchdog_process=`ps -C alcasar-watchdog.sh|wc -l`
if [[ $(expr $watchdog_process) -gt 3 ]]
then
echo "ALCASAR watchdog is already running"
exit 0
fi
# EXTIF testing
LAN_DOWN="0"
if [ `/sbin/ip link | grep $EXTIF|grep "NO-CARRIER" | wc -l` -eq "1" ]
then
LAN_DOWN="1"
fi
# Default GW testing
if [ $LAN_DOWN -eq "0" ]
then
GW_EXIST=`/sbin/ip route list|grep ^default|wc -l`
if [ $GW_EXIST -eq "0" ] # no GW defined !
then
systemctl restart network
else
IP_GW=`/sbin/ip route list|grep ^default|cut -d" " -f3`
arp_reply=`/usr/sbin/arping -I$EXTIF -c1 $IP_GW|grep response|cut -d" " -f2`
if [ $arp_reply -eq "0" ]
then
LAN_DOWN="2"
fi
fi
fi
# DNS request testing (twice)
if [ $LAN_DOWN -eq "0" ]
then
dns_reply=`/usr/bin/host -W1 www.free.fr|grep SERVFAIL|wc -l`
if [ $dns_reply -eq "1" ]
then
dns_reply=`/usr/bin/host -W1 www.startpage.com|grep SERVFAIL|wc -l`
if [ $dns_reply -eq "1" ]
then LAN_DOWN="3"
fi
fi
fi
# if LAN pb detected, users are warned
if [ $LAN_DOWN != "0" ]
then
lan_down_alert
# else switch in normal mode
else
echo "Internet access is OK for now"
net_pb=`grep "network_pb = true;" $Index_Page|wc -l`
if [ $net_pb != "0" ]
then
/bin/sed -i "s?^\$network_pb.*?\$network_pb = false;?g" $Index_Page
$IPTABLES -D PREROUTING -t nat -i $TUNIF -p udp --dport domain -j REDIRECT --to-port 56
fi
fi
}
usage="Usage: alcasar-watchdog.sh {-lt --lan_test | --disconnect-permanent-users}"
case $1 in
-\? | -h* | --h*)
echo "$usage"
exit 0
;;
-lt | --lan_test)
lan_test
exit 0
;;
--disconnect-permanent-users)
/bin/sed -i '/PERM/d' $current_users_file
exit 0
;;
*)
lan_test
# We disconnect inactive users (its means that their 'status.php' tab has been closed --> their ip address isn't in $current_users_file)
# process each equipment known by chilli
for system in `/usr/sbin/chilli_query list | grep -v "0\.0\.0\.0"`
do
active_ip=`echo $system |cut -d" " -f2`
active_session=`echo $system |cut -d" " -f5`
active_mac=`echo $system | cut -d" " -f1`
active_user=`echo $system |cut -d" " -f6`
# We check if the user isn't an auth @MAC and if he is still connected
if [ "$active_user" != "$active_mac" ] && [ $(expr $active_session) -eq 1 ]; then
if [ -e $current_users_file ]; then
# We check if user @IP is in 'current_users.txt'
cmp_user_ok=$(cat $current_users_file | awk -F':' "\$1 == \"$active_ip\" {print \$2}")
# If not we disconnect this user.
if [ -z "$cmp_user_ok" ]; then
logger -t alcasar-watchdog "$active_ip ($active_mac) doesn't contact ALCASAR any more. We disconnects the user ($active_user)."
/usr/sbin/chilli_query logout $active_mac
elif [ "$cmp_user_ok" == "TEMP" ]; then
# Remove the user's IP from 'current_users.txt'. Every user status page need to insert their @IP everytime to prove their connectivity.
# We don't disconnect when $cmp_user_ok == "PERM" (status page not needed)
sed -i "/^$active_ip:$cmp_user_ok\$/d" $current_users_file
fi
else # "current_user.txt" does not exists. We disconnect every users.
logger -t alcasar-watchdog "The file /tmp/current_users.txt doesn't' exist. We disconnects the user $active_user"
/usr/sbin/chilli_query logout $active_mac
fi
fi
# IP usurpation test : process only equipment with an authenticated user
if [[ $(expr $active_session) -eq 1 ]]
then
arp_reply=`/usr/sbin/arping -b -I$INTIF -s$PRIVATE_IP -c1 -w4 $active_ip|grep -c "Unicast reply"`
# disconnect users whose equipement is usurped. For example, if there are 2 same @MAC it will make 2 lines in output.
if [[ $(expr $arp_reply) -gt 1 ]]
then
echo "[$(date +"%Y-%m-%d %H:%M:%S")] : alcasar-watchdog : $active_ip is usurped ($active_mac). Alcasar disconnect the user ($active_user)." >> /var/Save/security/watchdog.log
logger -t alcasar-watchdog "$active_ip is usurped ($active_mac). Alcasar disconnect the user ($active_user)."
/usr/sbin/chilli_query logout $active_mac
chmod 644 /var/Save/security/watchdog.log
fi
fi
done
;;
esac
IFS=$OLDIFS