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 $IP -j DROP fi done
方法2：通过建立连接数
ABNORMAL_IP=$(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
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 192.168.1.1 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
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=$1 KEY=$2 for FILE in $(find $DIR -type f); do if grep $KEY $FILE &>/dev/null; then echo "--> $FILE" fi done
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/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。
12.17 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 $OUT)" sleep 1 done
12.18 MySQL数据库备份
#!/bin/bash DATE=$(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 $BACKUP_DIR -name '*.zip' -ctime +14 -exec rm {} \;
12.19 Nginx启动脚本
#!/bin/bash # Description: Only support RedHat system . /etc/init.d/functions WORD_DIR=/data/project/nginx1.10 DAEMON=$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
12.20 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/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
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！
