编写脚本

#!/bin/sh
echo $$ >/var/log/network.pid 
n=0
while true;do
          tcpdumpid=`ps aux |grep tcpdump|awk '/^tcpdump/{print $2}'`
          curl www.baidu.com &> /dev/null
          if [ $? -ne 0 ];then
                    echo "$n network web curl false..." >>/var/log/error.log
                    num=`ps aux | grep tcpdump | wc -l`
                      if [ $num -eq 1 ];then
                                tcpdump -nn -vv -i eth0 -w /var/log/server_11.cap &
                      fi
          else
                    kill $tcpdumpid &> /dev/null
                    echo "$n network web curl ok..." >> /var/log/net.log
          fi
let n=$n+1
sleep 2
done

为其服务脚本添加启动脚本

#!/bin/sh
. /etc/init.d/functions
function start() {
          if [ -f /tmp/network.pid ];then
                    action "network.sh is already running..."  /bin/false
                    exit 1
          else
                    sh /tmp/network.sh &
                    action "network.sh starting..."  /bin/true
          fi
}
function stop() {
          if [ -f /tmp/network.pid ];then
                    kill `cat /tmp/network.pid`
                    rm -fr /var/log/network.pid
                    action "network.sh stopping..."  /bin/true
          else
                    action "network.sh is already stopping..."  /bin/false
                    exit 2
          fi}
case $1 in
          start)
              start    ;;
          stop)
              stop
              ;;
  restart)
              stop
    start
              ;;
          *)
              echo "Usg:$0 start|stop|restart!"
              ;;
esac