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第十二章 Shell脚本编写及常见面试题(二)

发表于:2024-11-24 作者:千家信息网编辑
千家信息网最后更新 2024年11月24日,本章目录:12.11 屏蔽网站访问频繁的IP1)屏蔽每分钟访问超过200的IP方法1:以Nginx日志作为测试DATE=$(date +%d/%b/%Y:%H:%M)ABNORMAL_IP=$(tai
千家信息网最后更新 2024年11月24日第十二章 Shell脚本编写及常见面试题(二)

本章目录:

12.11 屏蔽网站访问频繁的IP

1)屏蔽每分钟访问超过200的IP

方法1:以Nginx日志作为测试

DATE=$(date +%d/%b/%Y:%H:%M)ABNORMAL_IP=$(tail -n5000 access.log |grep $DATE |awk '{a[$1]++}END{for(i in a)if(a[i]>100)print i}')#先tail防止文件过大,读取慢,数字可调整每分钟最大的访问量。awk不能直接过滤日志,因为包含特殊字符。for IP in $ABNORMAL_IP; do    if [ $(iptables -vnL |grep -c "$IP") -eq 0 ]; then        iptables -I INPUT -s $IP -j DROP    fidone

方法2:通过建立连接数

ABNORMAL_IP=$(netstat -an |awk '$4~/:80$/ && $6~/ESTABLISHED/{gsub(/:[0-9]+/,"",$5);{a[$5]++}}END{for(i in a)if(a[i]>100)print i}')#gsub是将第五列(客户端IP)的冒号和端口去掉for IP in $ABNORMAL_IP; do    if [ $(iptables -vnL |grep -c "$IP") -eq 0 ]; then        iptables -I INPUT -s $IP -j DROP    fidone

2)屏蔽每分钟SSH暴力破解超过10次的IP

方法1:通过lastb获取登录状态:

DATE=$(date +"%a %b %e %H:%M") #星期月天时分  %e单数字时显示7,而%d显示07ABNORMAL_IP=$(lastb |grep "$DATE" |awk '{a[$3]++}END{for(i in a)if(a[i]>10)print i}')for IP in $ABNORMAL_IP; do    if [ $(iptables -vnL |grep -c "$IP") -eq 0 ]; then        iptables -I INPUT -s $IP -j DROP    fidone

方法2:通过日志获取登录状态

DATE=$(date +"%b %d %H")ABNORMAL_IP="$(tail -n10000 /var/log/auth.log |grep "$DATE" |awk '/Failed/{a[$(NF-3)]++}END{for(i in a)if(a[i]>5)print i}')"for IP in $ABNORMAL_IP; do    if [ $(iptables -vnL |grep -c "$IP") -eq 0 ]; then        iptables -A INPUT -s $IP -j DROP        echo "$(date +"%F %T") - iptables -A INPUT -s $IP -j DROP" >>~/ssh-login-limit.log    fidone

12.12 判断输入是否为IP

方法1:

function check_ip(){    IP=$1    VALID_CHECK=$(echo $IP|awk -F. '$1<=255&&$2<=255&&$3<=255&&$4<=255{print "yes"}')    if echo $IP|grep -E "^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$">/dev/null; then        if [ $VALID_CHECK == "yes" ]; then            echo "$IP available."        else            echo "$IP not available!"        fi    else        echo "Format error!"    fi}check_ip 192.168.1.1check_ip 256.1.1.1

方法2:

function check_ip(){    IP=$1    if [[ $IP =~ ^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$ ]]; then        FIELD1=$(echo $IP|cut -d. -f1)        FIELD2=$(echo $IP|cut -d. -f2)        FIELD3=$(echo $IP|cut -d. -f3)        FIELD4=$(echo $IP|cut -d. -f4)        if [ $FIELD1 -le 255 -a $FIELD2 -le 255 -a $FIELD3 -le 255 -a $FIELD4 -le 255 ]; then            echo "$IP available."        else            echo "$IP not available!"        fi    else        echo "Format error!"    fi}check_ip 192.168.1.1check_ip 256.1.1.1

增加版:加个死循环,如果IP可用就退出,不可用提示继续输入,并使用awk判断

function check_ip(){    local IP=$1    VALID_CHECK=$(echo $IP|awk -F. '$1<=255&&$2<=255&&$3<=255&&$4<=255{print "yes"}')    if echo $IP|grep -E "^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$" >/dev/null; then        if [ $VALID_CHECK == "yes" ]; then            return 0        else            echo "$IP not available!"            return 1        fi    else        echo "Format error! Please input again."        return 1    fi}while true; do    read -p "Please enter IP: " IP    check_ip $IP    [ $? -eq 0 ] && break || continuedone

12.13 判断输入是否为数字

方法1:if [[ $1 =~ ^[0-9]+$ ]]; then    echo "Is Number."else    echo "No Number."fi方法2:if [ $1 -gt 0 ] 2>/dev/null; then    echo "Is Number."else    echo "No Number."fi

方法3:

echo $1 |awk '{print $0~/^[0-9]+$/?"Is Number.":"No Number."}'  #三目运算符12.14 找出包含关键字的文件DIR=$1KEY=$2for FILE in $(find $DIR -type f); do    if grep $KEY $FILE &>/dev/null; then        echo "--> $FILE"    fidone

12.15 监控目录,将新创建的文件名追加到日志中

需安装inotify-tools软件包。

#!/bin/bashMON_DIR=/optinotifywait -mq --format %f -e create $MON_DIR |\while read files; do  echo $files >> test.logdone12.16 多个网卡选择function local_nic() {    local NUM ARRAY_LENGTH    NUM=0    for NIC_NAME in $(ls /sys/class/net|grep -vE "lo|docker0"); do        NIC_IP=$(ifconfig $NIC_NAME |awk -F'[: ]+' '/inet addr/{print $4}')        if [ -n "$NIC_IP" ]; then            NIC_IP_ARRAY[$NUM]="$NIC_NAME:$NIC_IP"    #将网卡名和对应IP放到数组            let NUM++        fi    done    ARRAY_LENGTH=${#NIC_IP_ARRAY[*]}    if [ $ARRAY_LENGTH -eq 1 ]; then     #如果数组里面只有一条记录说明就一个网卡        NIC=${NIC_IP_ARRAY[0]%:*}        return 0    elif [ $ARRAY_LENGTH -eq 0 ]; then   #如果没有记录说明没有网卡        echo "No available network card!"        exit 1    else        #如果有多条记录则提醒输入选择        for NIC in ${NIC_IP_ARRAY[*]}; do            echo $NIC        done        while true; do            read -p "Please enter local use to network card name: " INPUT_NIC_NAME            COUNT=0            for NIC in ${NIC_IP_ARRAY[*]}; do                NIC_NAME=${NIC%:*}                if [ $NIC_NAME == "$INPUT_NIC_NAME" ]; then                    NIC=${NIC_IP_ARRAY[$COUNT]%:*}                    return 0                else                   COUNT+=1                fi            done            echo "Not match! Please input again."        done    fi}local_nic

如果有只有一个网卡就不选择。

12.17 查看网卡实时流量

#!/bin/bash# Description: Only CentOS6traffic_unit_conv() {    local traffic=$1    if [ $traffic -gt 1024000 ]; then        printf "%.1f%s" "$(($traffic/1024/1024))" "MB/s"    elif [ $traffic -lt 1024000 ]; then        printf "%.1f%s" "$(($traffic/1024))" "KB/s"    fi}NIC=$1echo -e " In ------ Out"while true; do    OLD_IN=$(awk -F'[: ]+' '$0~"'$NIC'"{print $3}' /proc/net/dev)    OLD_OUT=$(awk -F'[: ]+' '$0~"'$NIC'"{print $11}' /proc/net/dev)    sleep 1    NEW_IN=$(awk -F'[: ]+' '$0~"'$NIC'"{print $3}' /proc/net/dev)    NEW_OUT=$(awk -F'[: ]+' '$0~"'$NIC'"{print $11}' /proc/net/dev)    IN=$(($NEW_IN-$OLD_IN))    OUT=$(($NEW_OUT-$OLD_OUT))    echo "$(traffic_unit_conv $IN) $(traffic_unit_conv $OUT)"    sleep 1done# 也可以通过ficonfig命令获取收发流量while true; do    OLD_IN=$(ifconfig $NIC |awk -F'[: ]+' '/bytes/{print $4}')      OLD_OUT=$(ifconfig $NIC |awk -F'[: ]+' '/bytes/{print $9}')    sleep 1    NEW_IN=$(ifconfig $NIC |awk -F'[: ]+' '/bytes/{print $4}')    NEW_OUT=$(ifconfig $NIC |awk -F'[: ]+' '/bytes/{print $9}')    IN=$(($NEW_IN-$OLD_IN))    OUT=$(($NEW_OUT-$OLD_OUT))    echo "$(traffic_unit_conv $IN) $(traffic_unit_conv $OUT)"    sleep 1done

12.18 MySQL数据库备份

#!/bin/bashDATE=$(date +%F_%H-%M-%S)HOST=192.168.1.120DB=testUSER=bakPASS=123456MAIL="zhangsan@example.com lisi@example.com"BACKUP_DIR=/data/db_backupSQL_FILE=${DB}_full_$DATE.sqlBAK_FILE=${DB}_full_$DATE.zipcd $BACKUP_DIRif mysqldump -h$HOST -u$USER -p$PASS --single-transaction --routines --triggers -B $DB > $SQL_FILE; then    zip $BAK_FILE $SQL_FILE && rm -f $SQL_FILE    if [ ! -s $BAK_FILE ]; then            echo "$DATE 内容" | mail -s "主题" $MAIL    fielse    echo "$DATE 内容" | mail -s "主题" $MAILfifind $BACKUP_DIR -name '*.zip' -ctime +14 -exec rm {} \;

12.19 Nginx启动脚本

#!/bin/bash# Description: Only support RedHat system. /etc/init.d/functionsWORD_DIR=/data/project/nginx1.10DAEMON=$WORD_DIR/sbin/nginxCONF=$WORD_DIR/conf/nginx.confNAME=nginxPID=$(awk -F'[; ]+' '/^[^#]/{if($0~/pid;/)print $2}' $CONF)if [ -z "$PID" ]; then    PID=$WORD_DIR/logs/nginx.pidelse    PID=$WORD_DIR/$PIDfistop() {    $DAEMON -s stop    sleep 1    [ ! -f $PID ] && action "* Stopping $NAME"  /bin/true || action "* Stopping $NAME" /bin/false}start() {    $DAEMON    sleep 1    [ -f $PID ] && action "* Starting $NAME"  /bin/true || action "* Starting $NAME" /bin/false}reload() {    $DAEMON -s reload}test_config() {    $DAEMON -t}case "$1" in    start)        if [ ! -f $PID ]; then            start        else            echo "$NAME is running..."            exit 0        fi        ;;    stop)        if [ -f $PID ]; then            stop        else            echo "$NAME not running!"            exit 0        fi        ;;    restart)        if [ ! -f $PID ]; then            echo "$NAME not running!"             start        else            stop            start        fi        ;;    reload)        reload        ;;    testconfig)        test_config        ;;     status)        [ -f $PID ] && echo "$NAME is running..." || echo "$NAME not running!"        ;;    *)        echo "Usage: $0 {start|stop|restart|reload|testconfig|status}"        exit 3        ;;esac

12.20 选择SSH连接主机

写一个配置文件保存被监控主机SSH连接信息,文件内容格式:主机名 IP User Port

#!/bin/bashPS3="Please input number: "HOST_FILE=hostwhile true; do    select NAME in $(awk '{print $1}' $HOST_FILE) quit; do        [ ${NAME:=empty} == "quit" ] && exit 0        IP=$(awk -v NAME=${NAME} '$1==NAME{print $2}' $HOST_FILE)        USER=$(awk -v NAME=${NAME} '$1==NAME{print $3}' $HOST_FILE)        PORT=$(awk -v NAME=${NAME} '$1==NAME{print $4}' $HOST_FILE)        if [ $IP ]; then            echo "Name: $NAME, IP: $IP"            ssh -o StrictHostKeyChecking=no -p $PORT -i id_rsa $USER@$IP  # 密钥登录            break        else            echo "Input error, Please enter again!"            break        fi    donedone

本章写的Shell脚本例子都比较实用,在面试题中也经常出现,希望大家参考着多动手写写,不要复制粘贴就拿来跑,这样是学不会的!有问题请加×××流:323779636(Shell/Python运维开发群)


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