Persistent Packet Capture

#!/bin/sh
#
# Startup script for persistent tcpdump
#
# chkconfig: 345 86 14
# description: Packet Capture
# processname: tcpdump

PCAP=/mnt/tcpdump/tcpdump.pcap
SIZE=100
COUNT=20
PIDFILE=/var/run/tcpdump

start() {
        if [ -f $PIDFILE ]; then
                echo "PID File $PIDFILE exists"
                exit 1
        fi
        tcpdump -nn -w $PCAP -s0 -C $SIZE -W $COUNT -Z root not port 22 > /dev/null 2>&1 &
        echo $! > $PIDFILE
        exit 0
}

stop() {
        if [ ! -f $PIDFILE ]; then
                echo "PID File $PIDFILE does not exist"
                exit 1
        fi
        kill -HUP `cat $PIDFILE` && rm $PIDFILE
        exit $@
}

status() {
        if [ ! -f $PIDFILE ]; then
                echo "PID File $PIDFILE does not exist"
                exit 0
        fi
        ps -fp `cat $PIDFILE`
        exit 0
}

case "$1" in
  start)
        start
        ;;
  stop)
        stop
        ;;
  status)
        status
        ;;
  *)
        echo "Usage: $0 {start|stop|status}"
        exit 1
esac