如何編寫一個強大的網絡分析shell腳本

本篇內容介紹了“如何編寫一個強大的網絡分析shell腳本”的有關知識，在實際案例的操作過程中，不少人都會遇到這樣的困境，接下來就讓小編帶領大家學習一下如何處理這些情況吧！希望大家仔細閱讀，能夠學有所成！

腳本運行效果截圖：

此腳本包含的功能有：

1、實時監控任意網卡的流量
2、統計10秒內平均流量
3、統計每個端口在10秒內的平均流量，基于客戶端和服務端端口統計。可以看出哪些端口占流量比較大，對于web服務器，一般是80端口。其它端口受到攻擊時，也有可能其它端口流量比較大。所以此功能可以幫助我們端口流量是否正常。
4、統計在10s內占用帶寬最大的前10個ip。此項功能可以幫助我們來查出是否有惡意占用帶寬的ip。
5、統計連接狀態。此項功能可以讓我們看出哪些連接狀態比較大。如果SYN-RECV狀態比較多的話，有可以受到半連接攻擊。如果ESTABLISED非常大，但通過日志發現沒有那么多請求，或者通過tcpdump發現大量ip只建立連接不請求數據的話，可能是受到了全連接攻擊，這時候如果你使用的是nginx服務器，可以在配置文件增加listen 80 deferred來防止。
6、統計各端口連接狀態。當可能受到攻擊時，此項功能可以幫助我們發現是哪個端口受到攻擊。
7、統計端口為80且狀態為ESTAB連接數最多的前10個IP。此項功能可以幫助我們來找出創建連接過多的Ip，進而屏蔽。
8、統計端口為80且狀態為SYN-RECV連接數最多的前10個IP。當受到半連接攻擊時，此項功能可以幫助我們找到惡意ip。

用到的網絡分析工具：

1、tcpdump:此腳本用tcpdump來統計基于ip或基于端口的流量。
2、ss： 此腳本用ss命令來統計連接狀態，實際使用發現ss比netstat高效得多。
3、/proc/net/dev，用來統計指定網卡的流量。
腳本下載地址：https://www.centos.bz/wp-content/uploads/2014/06/network-analysis.sh
下面貼出完整的腳本：

代碼如下:

#!/bin/bash
 
#write by zhumaohai(admin#centos.bz)
 
#顯示菜單(單選)
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
}
 
#把帶寬bit單位轉換為人類可讀單位
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
}
 
#判斷包管理工具
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  
}
 
 
#實時流量
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
        #移動光標到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,$11}}' /proc/net/dev`)
        #計算速率
        eth_in=$(( (${traffic_af[0]}-${traffic_be[0]})*8/2 ))
        eth_out=$(( (${traffic_af[1]}-${traffic_be[1]})*8/2 ))
        #計算流量峰值
        [[ $eth_in -gt $eth_in_peak ]] && eth_in_peak=$eth_in
        [[ $eth_out -gt $eth_out_peak ]] && eth_out_peak=$eth_out
        #移動光標到2:1
        printf "\033[2;1H"
        #清除當前行
        printf "\033[K"  
        printf "%-20s %-20s\n" "Receive:  $(bit_to_human_readable $eth_in)" "$(bit_to_human_readable $eth_in_peak)"
        #清除當前行
        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
}
 
#流量和連接概覽
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
    #當前流量值
    local traffic_be=(`awk -v eth=$eth -F'[: ]+' '{if ($0 ~eth){print $3,$11}}' /proc/net/dev`)
    #tcpdump監聽網絡
    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]+:/')
 
    #新舊版本tcpdump輸出格式不一樣,分別處理
    if awk '/^IP/{print;exit}' /tmp/tcpdump_temp | grep -q ")$";then
        #處理tcpdump文件
        awk '/^IP/{print;getline;print}' /tmp/tcpdump_temp > /tmp/tcpdump_temp2
    else
        #處理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

    #統計每個端口在10s內的平均流量
    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

    #統計在10s內占用帶寬最大的前10個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
    #統計連接狀態
    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
    #統計各端口連接狀態
    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"$0}'  
    echo  
    #統計端口為80且狀態為ESTAB連接數最多的前10個IP
    echo -e "\033[32mtop 10 ip ESTAB state count at port 80: \033[0m"
    cat /tmp/ss | grep ESTAB | awk -F'[: ]+' '{sum[$(NF-2)]+=1}END{for (ip in sum){print ip,sum[ip]}}' | sort -k 2 -nr | head -n 10
    echo
    #統計端口為80且狀態為SYN-RECV連接數最多的前10個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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