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本篇内容介绍了“如何编写一个强大的网络分析shell脚本”的有关知识，在实际案例的操作过程中，不少人都会遇到这样的困境，接下来就让小编带领大家学习一下如何处理这些情况吧！希望大家仔细阅读，能够学有所成！
脚本运行效果截图：
此脚本包含的功能有：
1、实时监控任意网卡的流量
2、统计10秒内平均流量
3、统计每个端口在10秒内的平均流量，基于客户端和服务端端口统计。可以看出哪些端口占流量比较大，对于web服务器，一般是80端口。其它端口受到攻击时，也有可能其它端口流量比较大。所以此功能可以帮助我们端口流量是否正常。
4、统计在10s内占用带宽较大的前10个ip。此项功能可以帮助我们来查出是否有恶意占用带宽的ip。
5、统计连接状态。此项功能可以让我们看出哪些连接状态比较大。如果SYN-RECV状态比较多的话，有可以受到半连接攻击。如果ESTABLISED非常大，但通过日志发现没有那么多请求，或者通过tcpdump发现大量ip只建立连接不请求数据的话，可能是受到了全连接攻击，这时候如果你使用的是nginx服务器，可以在配置文件增加listen 80 deferred来防止。
6、统计各端口连接状态。当可能受到攻击时，此项功能可以帮助我们发现是哪个端口受到攻击。
7、统计端口为80且状态为ESTAB连接数最多的前10个IP。此项功能可以帮助我们来找出创建连接过多的Ip，进而屏蔽。
8、统计端口为80且状态为SYN-RECV连接数最多的前10个IP。当受到半连接攻击时，此项功能可以帮助我们找到恶意ip。
用到的网络分析工具：
1、tcpdump:此脚本用tcpdump来统计基于ip或基于端口的流量。
2、ss： 此脚本用ss命令来统计连接状态，实际使用发现ss比netstat高效得多。
3、/proc/net/dev，用来统计指定网卡的流量。
脚本下载地址：https://www.centos.bz/wp-content/uploads/2014/06/network-analysis.sh
下面贴出完整的脚本：
代码如下:
#!/bin/bash
#write by zhumaohai(admin#centos.bz)
#显示菜单(单选)
display_menu(){
local soft=$1
local prompt="which ${soft} you'd select: "
eval local arr=(\${${soft}_arr[@]})
while true
do
echo -e "#################### ${soft} setting ####################\n\n"
for ((i=1;i<=${#arr[@]};i++ )); do echo -e "$i) ${arr[$i-1]}"; done
echo
read -p "${prompt}" $soft
eval local select=\$$soft
if [ "$select" == "" ] || [ "${arr[$soft-1]}" == "" ];then
prompt="input errors,please input a number: "
else
eval $soft=${arr[$soft-1]}
eval echo "your selection: \$$soft"
break
fi
done
}
#把带宽bit单位转换为人类可读单位
bit_to_human_readable(){
#input bit value
local trafficValue=$1
if [[ ${trafficValue%.*} -gt 922 ]];then
#conv to Kb
trafficValue=`awk -v value=$trafficValue 'BEGIN{printf "%0.1f",value/1024}'`
if [[ ${trafficValue%.*} -gt 922 ]];then
#conv to Mb
trafficValue=`awk -v value=$trafficValue 'BEGIN{printf "%0.1f",value/1024}'`
echo "${trafficValue}Mb"
else
echo "${trafficValue}Kb"
fi
else
echo "${trafficValue}b"
fi
}
#判断包管理工具
check_package_manager(){
local manager=$1
local systemPackage=''
if cat /etc/issue | grep -q -E -i "ubuntu|debian";then
systemPackage='apt'
elif cat /etc/issue | grep -q -E -i "centos|red hat|redhat";then
systemPackage='yum'
elif cat /proc/version | grep -q -E -i "ubuntu|debian";then
systemPackage='apt'
elif cat /proc/version | grep -q -E -i "centos|red hat|redhat";then
systemPackage='yum'
else
echo "unkonw"
fi
if [ "$manager" == "$systemPackage" ];then
return 0
else
return 1
fi
}
#实时流量
realTimeTraffic(){
local eth=""
local nic_arr=(`ifconfig | grep -E -o "^[a-z0-9]+" | grep -v "lo" | uniq`)
local nicLen=${#nic_arr[@]}
if [[ $nicLen -eq 0 ]]; then
echo "sorry,I can not detect any network device,please report this issue to author."
exit 1
elif [[ $nicLen -eq 1 ]]; then
eth=$nic_arr
else
display_menu nic
eth=$nic
fi
local clear=true
local eth_in_peak=0
local eth_out_peak=0
local eth_in=0
local eth_out=0
while true;do
#移动光标到0:0位置
printf "\033[0;0H"
#清屏并打印Now Peak
[[ $clear == true ]] && printf "\033[2J" && echo "$eth--------Now--------Peak-----------"
traffic_be=(`awk -v eth=$eth -F'[: ]+' '{if ($0 ~eth){print $3,$11}}' /proc/net/dev`)
sleep 2
traffic_af=(`awk -v eth=$eth -F'[: ]+' '{if ($0 ~eth){print $3,$11}}' /proc/net/dev`)
#计算速率
eth_in=$(( (${traffic_af[0]}-${traffic_be[0]})*8/2 ))
eth_out=$(( (${traffic_af[1]}-${traffic_be[1]})*8/2 ))
#计算流量峰值
[[ $eth_in -gt $eth_in_peak ]] && eth_in_peak=$eth_in
[[ $eth_out -gt $eth_out_peak ]] && eth_out_peak=$eth_out
#移动光标到2:1
printf "\033[2;1H"
#清除当前行
printf "\033[K"
printf "%-20s %-20s\n" "Receive: $(bit_to_human_readable $eth_in)" "$(bit_to_human_readable $eth_in_peak)"
#清除当前行
printf "\033[K"
printf "%-20s %-20s\n" "Transmit: $(bit_to_human_readable $eth_out)" "$(bit_to_human_readable $eth_out_peak)"
[[ $clear == true ]] && clear=false
done
}
#流量和连接概览
trafficAndConnectionOverview(){
if ! which tcpdump > /dev/null;then
echo "tcpdump not found,going to install it."
if check_package_manager apt;then
apt-get -y install tcpdump
elif check_package_manager yum;then
yum -y install tcpdump
fi
fi
local reg=""
local eth=""
local nic_arr=(`ifconfig | grep -E -o "^[a-z0-9]+" | grep -v "lo" | uniq`)
local nicLen=${#nic_arr[@]}
if [[ $nicLen -eq 0 ]]; then
echo "sorry,I can not detect any network device,please report this issue to author."
exit 1
elif [[ $nicLen -eq 1 ]]; then
eth=$nic_arr
else
display_menu nic
eth=$nic
fi
echo "please wait for 10s to generate network data..."
echo
#当前流量值
local traffic_be=(`awk -v eth=$eth -F'[: ]+' '{if ($0 ~eth){print $3,$11}}' /proc/net/dev`)
#tcpdump监听网络
tcpdump -v -i $eth -tnn > /tmp/tcpdump_temp 2>&1 &
sleep 10
clear
kill `ps aux | grep tcpdump | grep -v grep | awk '{print $2}'`
#10s后流量值
local traffic_af=(`awk -v eth=$eth -F'[: ]+' '{if ($0 ~eth){print $3,$11}}' /proc/net/dev`)
#打印10s平均速率
local eth_in=$(( (${traffic_af[0]}-${traffic_be[0]})*8/10 ))
local eth_out=$(( (${traffic_af[1]}-${traffic_be[1]})*8/10 ))
echo -e "\033[32mnetwork device $eth average traffic in 10s: \033[0m"
echo "$eth Receive: $(bit_to_human_readable $eth_in)/s"
echo "$eth Transmit: $(bit_to_human_readable $eth_out)/s"
echo
local regTcpdump=$(ifconfig | grep -A 1 $eth | awk -F'[: ]+' '$0~/inet addr:/{printf $4"|"}' | sed -e 's/|$//' -e 's/^/(/' -e 's/$/)\\\\\.[0-9]+:/')
#新旧版本tcpdump输出格式不一样,分别处理
if awk '/^IP/{print;exit}' /tmp/tcpdump_temp | grep -q ")$";then
#处理tcpdump文件
awk '/^IP/{print;getline;print}' /tmp/tcpdump_temp > /tmp/tcpdump_temp2
else
#处理tcpdump文件
awk '/^IP/{print}' /tmp/tcpdump_temp > /tmp/tcpdump_temp2
sed -i -r 's#(.*: [0-9]+\))(.*)#\1\n \2#' /tmp/tcpdump_temp2
fi
awk '{len=$NF;sub(/\)/,"",len);getline;print $0,len}' /tmp/tcpdump_temp2 > /tmp/tcpdump
#统计每个端口在10s内的平均流量
echo -e "\033[32maverage traffic in 10s base on server port: \033[0m"
awk -F'[ .:]+' -v regTcpdump=$regTcpdump '{if ($0 ~ regTcpdump){line="clients > "$8"."$9"."$10"."$11":"$12}else{line=$2"."$3"."$4"."$5":"$6" > clients"};sum[line]+=$NF*8/10}END{for (line in sum){printf "%s %d\n",line,sum[line]}}' /tmp/tcpdump | \
sort -k 4 -nr | head -n 10 | while read a b c d;do
echo "$a $b $c $(bit_to_human_readable $d)/s"
done
echo -ne "\033[11A"
echo -ne "\033[50C"
echo -e "\033[32maverage traffic in 10s base on client port: \033[0m"
awk -F'[ .:]+' -v regTcpdump=$regTcpdump '{if ($0 ~ regTcpdump){line=$2"."$3"."$4"."$5":"$6" > server"}else{line="server > "$8"."$9"."$10"."$11":"$12};sum[line]+=$NF*8/10}END{for (line in sum){printf "%s %d\n",line,sum[line]}}' /tmp/tcpdump | \
sort -k 4 -nr | head -n 10 | while read a b c d;do
echo -ne "\033[50C"
echo "$a $b $c $(bit_to_human_readable $d)/s"
done
echo
#统计在10s内占用带宽较大的前10个ip
echo -e "\033[32mtop 10 ip average traffic in 10s base on server: \033[0m"
awk -F'[ .:]+' -v regTcpdump=$regTcpdump '{if ($0 ~ regTcpdump){line=$2"."$3"."$4"."$5" > "$8"."$9"."$10"."$11":"$12}else{line=$2"."$3"."$4"."$5":"$6" > "$8"."$9"."$10"."$11};sum[line]+=$NF*8/10}END{for (line in sum){printf "%s %d\n",line,sum[line]}}' /tmp/tcpdump | \
sort -k 4 -nr | head -n 10 | while read a b c d;do
echo "$a $b $c $(bit_to_human_readable $d)/s"
done
echo -ne "\033[11A"
echo -ne "\033[50C"
echo -e "\033[32mtop 10 ip average traffic in 10s base on client: \033[0m"
awk -F'[ .:]+' -v regTcpdump=$regTcpdump '{if ($0 ~ regTcpdump){line=$2"."$3"."$4"."$5":"$6" > "$8"."$9"."$10"."$11}else{line=$2"."$3"."$4"."$5" > "$8"."$9"."$10"."$11":"$12};sum[line]+=$NF*8/10}END{for (line in sum){printf "%s %d\n",line,sum[line]}}' /tmp/tcpdump | \
sort -k 4 -nr | head -n 10 | while read a b c d;do
echo -ne "\033[50C"
echo "$a $b $c $(bit_to_human_readable $d)/s"
done
echo
#统计连接状态
local regSS=$(ifconfig | grep -A 1 $eth | awk -F'[: ]+' '$0~/inet addr:/{printf $4"|"}' | sed -e 's/|$//')
ss -an | grep -v -E "LISTEN|UNCONN" | grep -E "$regSS" > /tmp/ss
echo -e "\033[32mconnection state count: \033[0m"
awk 'NR>1{sum[$(NF-4)]+=1}END{for (state in sum){print state,sum[state]}}' /tmp/ss | sort -k 2 -nr
echo
#统计各端口连接状态
echo -e "\033[32mconnection state count by port base on server: \033[0m"
awk 'NR>1{sum[$(NF-4),$(NF-1)]+=1}END{for (key in sum){split(key,subkey,SUBSEP);print subkey[1],subkey[2],sum[subkey[1],subkey[2]]}}' /tmp/ss | sort -k 3 -nr | head -n 10
echo -ne "\033[11A"
echo -ne "\033[50C"
echo -e "\033[32mconnection state count by port base on client: \033[0m"
awk 'NR>1{sum[$(NF-4),$(NF)]+=1}END{for (key in sum){split(key,subkey,SUBSEP);print subkey[1],subkey[2],sum[subkey[1],subkey[2]]}}' /tmp/ss | sort -k 3 -nr | head -n 10 | awk '{print "\033[50C"$0}'
echo
#统计端口为80且状态为ESTAB连接数最多的前10个IP
echo -e "\033[32mtop 10 ip ESTAB state count at port 80: \033[0m"
cat /tmp/ss | grep ESTAB | awk -F'[: ]+' '{sum[$(NF-2)]+=1}END{for (ip in sum){print ip,sum[ip]}}' | sort -k 2 -nr | head -n 10
echo
#统计端口为80且状态为SYN-RECV连接数最多的前10个IP
echo -e "\033[32mtop 10 ip SYN-RECV state count at port 80: \033[0m"
cat /tmp/ss | grep -E "$regSS" | grep SYN-RECV | awk -F'[: ]+' '{sum[$(NF-2)]+=1}END{for (ip in sum){print ip,sum[ip]}}' | sort -k 2 -nr | head -n 10
}
main(){
while true; do
echo -e "1) real time traffic.\n2) traffic and connection overview.\n"
read -p "please input your select(ie 1): " select
case $select in
1) realTimeTraffic;break;;
2) trafficAndConnectionOverview;break;;
*) echo "input error,please input a number.";;
esac
done
}
main
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