14-3.Shell脚本编写及常见面试题(二)

14.11 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
    fi
done

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
    fi
done

 

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=$(date +"%a %b %e %H:%M") #星期月天时分  %e单数字时显示7,而%d显示07
ABNORMAL_IP=$(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
    fi
done

 

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
    fi
done 

14.12 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 192.168.1.1
check_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 192.168.1.1
check_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 || continue
done

 

14.13 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:


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

12.14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/bash
MON_DIR=/opt
inotifywait -mq --format %f -e create $MON_DIR |\
while read files; do
  echo $files >> test.log
done
12.16 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。

12.15 查看网卡实时流量

#!/bin/bash
# Description: Only CentOS6
traffic_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=$1
echo -e " In ------ Out"
while true; do
    OLD_IN=$(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 $OUT)"
    sleep 1
done
# 也可以通过ficonfig命令获取收发流量
while true; do
    OLD_IN=$(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 1
done
 

 

12.16 MySQL数据库备份

#!/bin/bash
DATE=$(date +%F_%H-%M-%S)
HOST=192.168.1.120
DB=test
USER=bak
PASS=123456
MAIL="zhangsan@example.com lisi@example.com"
BACKUP_DIR=/data/db_backup
SQL_FILE=${DB}_full_$DATE.sql
BAK_FILE=${DB}_full_$DATE.zip
cd $BACKUP_DIR
if mysqldump -h$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" $MAIL
    fi
else
    echo "$DATE 内容" | mail -s "主题" $MAIL
fi
find $BACKUP_DIR -name '*.zip' -ctime +14 -exec rm {} \;
 

 

12.17 Nginx启动脚本

#!/bin/bash
# Description: Only support RedHat system
. /etc/init.d/functions
WORD_DIR=/data/project/nginx1.10
DAEMON=$WORD_DIR/sbin/nginx
CONF=$WORD_DIR/conf/nginx.conf
NAME=nginx
PID=$(awk -F'[; ]+' '/^[^#]/{if($0~/pid;/)print $2}' $CONF)
if [ -z "$PID" ]; then
    PID=$WORD_DIR/logs/nginx.pid
else
    PID=$WORD_DIR/$PID
fi
stop() {
    $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

 

12.18 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/bash
PS3="Please input number: "
HOST_FILE=host
while 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
    done
done

 

posted @ 2020-03-21 11:04  流氓徐志摩  阅读(252)  评论(0编辑  收藏  举报