reconnect.sh

Here is a Linux shell script to automatically reconnect a high speed Internet connection if you have been disconnected. It was written for OpenSuSE 10.2 with DSL connections and I haven't tested it anywhere else. However, it should be a good starting point for other systems.

It is meant to be run at startup in rc.local.

nohup nice sh /root/reconnect.sh &

On SuSE, boot.local cannot be used. Use a script like the following:

#!/bin/bash
# restart_reconnect.sh

TMP=`ps -ef`
# don't include this script in the grep
TMP=`echo "$TMP" | grep reconnect.sh | grep -v restart`
echo "$TMP"
if [ -z "$TMP" ] ; then
   nohup nice /bin/bash /root/reconnect.sh &
fi

and run it with the crontab command:

00,10,20,30,40,50       *       *       *       *       /bin/bash -c /root/restart_reconnect.sh

You many need to modify some of the variables at the start of the script to meet the requirements of your version of Linux.

---

#!/bin/bash
#
# reconnect.sh - check and reconnect a home high-speed internet connection
#
# January 19, 2007
# by Ken O. Burtch
#
# This was built for OpenSuSE 10.2 and DSL but it should be adaptable to other
# systems.
# This assumes you've configured your networking to use ifdown/up to control
# the high-speed connection.
#
# This script should be run from boot.local/rc.local.
# ---------------------------------------------------------------------------
set -u

# Configuration Settings (change as required)

CONNECTION="dsl0"                 # Name of the high-speed ifconfig device
SERVER="www.google.ca"            # Name of a server to test the connection
SERVER2="www.yahoo.ca"            # Backup test server

TMP="/tmp/reconnect.$$"           # Where to build log messages
LOG="/root/reconnect.log"         # The log
BACKUP_LOG="/root/reconnect.old"  # The last (old) log
LOCK="/tmp/reconnect_lock.$$"     # The lock file

# Commands (Correct these for your locations)

IFCONFIG="/sbin/ifconfig"         # View connections
IFUP="/sbin/ifup"                 # Start a connection
IFDOWN="/sbin/ifdown"             # Stop a connection
IFSTATUS="/sbin/ifstatus"         # Connection status
PING="/bin/ping"                  # Network Ping
TRACEROUTE="/usr/sbin/traceroute" # Network Trace

# Other Variables

DSL=
PING_RESULT=
PING_RESULT2=
TRACE=
TRACE_HOSTS=
CNT=
OK=


# Sanity Tests - check user, lock file and commands

if [ "$LOGNAME" != "root" ] ; then
   echo "$0: Must be root to run"
   exit 1
fi

if [ -f "$LOCK" ] ; then
   echo "$0: lock file $LOCK exists"
   exit 1
fi

if test ! -x "$IFCONFIG" ; then
   echo "$0: $IFCONFIG cannot be run"
   exit 1
fi

if test ! -x "$IFUP" ; then
   echo "$0: $IFUP cannot be run"
   exit 1
fi

if test ! -x "$IFDOWN" ; then
   echo "$0: $IFDOWN cannot be run"
   exit 1
fi

if test ! -x "$IFSTATUS" ; then
   echo "$0: $IFSTATUS cannot be run"
   exit 1
fi

if test ! -x "$PING" ; then
   echo "$0: $PING cannot be run"
   exit 1
fi

if test ! -x "$TRACEROUTE" ; then
   echo "$0: $TRACEROUTE cannot be run"
   exit 1
fi


# Startup

if [ -f "$LOG" ] ; then                                    # an existing log?
   mv "$LOG" "$BACKUP_LOG"                                 # back it up
fi

echo `date`": $0: restarted using PID $$" > "$LOG"         # start new log

let "CNT=4"                                                # force quality test
OK=                                                        # not sure we're OK

# Infinte loop

while true ; do

   touch "$LOCK"                                           # one at a time

   # DSL Reconnect Test (using ifup)

   DSL=`$IFCONFIG | fgrep "$CONNECTION"`                   # connect up?
   if [ -z "$DSL" ] ; then                                 # if not
      OK=                                                  # we're not OK
      echo `date`": --------------------------------------------------" >> "$TMP"
      $IFSTATUS "$CONNECTION" >> "$TMP" 2>&1               # show status
      echo `date`": reconnect $CONNECTION..." >> "$TMP"    # info message
      $IFDOWN "$CONNECTION" >> "$TMP" 2>&1                 # clean shutdown
      $IFUP   "$CONNECTION" >> "$TMP" 2>&1                 # and startup
      DSL=`$IFCONFIG | fgrep "$CONNECTION"`                # connection up?
      if [ -z "$DSL" ] ; then                              # if not
         echo `date`": RECONNECT FAILED" >> "$TMP"         # fail message
      else                                                 # otherwise
         echo `date`": OK" >> "$TMP"                       # we're back
      fi
   fi


   # Connection Quality Test
   # only do this every 5th loop (10 minutes)

   let "CNT++"                                             # inc counter
   if [ $CNT -ge 5 ] ; then                                # 5th time?
      let "CNT=0"                                          # reset counter
      DSL=`$IFCONFIG | fgrep "$CONNECTION"`                # connection up?
      if [ ! -z "$DSL" ] ; then                            # then proceed
         PING_RESULT=`$PING -c 1 "$SERVER" 2>&1`           # see test server?
         if [ $? -ne 0 ] ; then                            # no
            PING_RESULT2=`$PING -c 1 "$SERVER2" 2>&1`      # try secondary
            if [ $? -ne 0 ] ; then                         # still no?
               OK=                                         # not OK
               echo `date`": --------------------------------------------------" >> "$TMP"
               echo `date`": cannot reach $SERVER or $SERVER2 (via ping)..." >> "$TMP"
               echo "$PING_RESULT" >> "$TMP"
               echo "$PING_RESULT2" >> "$TMP"
               echo `date`": tracing connection to $SERVER (via traceroute)..." >> "$TMP"
               TRACE=`$TRACEROUTE -m 10 "$SERVER" 2>&1`    # trace problem
               TRACE_HOSTS=`echo "$TRACE" | grep -v \* | wc -l` # good hosts
               echo "$TRACE" >> "$TMP"                     # show trace
               if [ $TRACE_HOSTS -gt 3 ] ; then            # 3 good hosts?
                  echo `date`": failure at or near $SERVER" >> "$TMP"
                  # 4 or more hops?  somewhere on the internet or at test server
               elif [ $TRACE_HOSTS -gt 2 ] ; then          # 2 good hosts?
                  echo `date`": FAILURE AT INTERNET PROVIDER" >> "$TMP"
                  # 3 hops?  you to internet provider's provider
               elif [ $TRACE_HOSTS -gt 1 ] ; then          # 1 good host?
                  echo `date`": FAILURE AT INTERNET PROVIDER" >> "$TMP"
                  # 2 hops?  you to internet provider
               else                                        # should not happen
                  echo `date`": UNABLE TO REACH INTERNET PROVIDER" >> "$TMP"
                  # 1 hop? didn't get to first computer after this one.  how did
                  # we log in?
               fi
            elif [ -z "$OK" ] ; then                       # ping good?
               echo `date`": OK" >> "$TMP"                 # we're OK
               OK=1
            fi
         elif [ -z "$OK" ] ; then                          # ping good?
            echo `date`": OK" >> "$TMP"                    # we're OK
            OK=1
         fi
      fi
   fi


   # Cleanup

   if test -s "$TMP" ; then                                # messages?
      cat "$TMP" >> "$LOG"                                 # copy to log
      rm "$TMP"                                            # remove msgs
   fi

   rm "$LOCK"                                              # remove lock

   sleep 120                                               # every 2 minutes

done

# Should not get here

exit 0