Linux系统调优及安全设置
1、更改yum源:
mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup <<-备份系统自带yum源 wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-6.repo <<—国内使用阿里云yum源速度比较快 wget -O /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-6.repo 注:镜像官方网址http://mirrors.aliyun.com/ 如有自建yum仓可以更改成自建yum仓地址信息
2、关闭selinux
永久关闭(需要重启系统) sed -i 's/SELINUX=enforcing/SELINUX=disabled/' /etc/selinux/config 临时关闭(无需重启) setenforce 0 数字0表示Premissive,即给出警告提示,不会阻止操作,相当于disabled 数字1表示Enfocing,即表示SELinux为开启状态 getenforce <<-查看selinux当前状态
3、关闭iptables
/etc/init.d/iptables stop <<-关闭iptables服务 /etc/init.d/iptables status <<-查看iptables状态 chkconfig iptables off <<—开机启动关闭
4、精简开机启动
chkconfig|egrep -v "crond|sshd|network|rsyslog|sysstat"|awk '{print "chkconfig",$1,"off"}'|bash <<-关闭服务 chkconfig --list|grep 3:on <<-检查开机启动的服务
5、更改字符集(选做)
cp /etc/sysconfig/i18n /etc/sysconfig/i18n.ori echo 'LANG="zh_CN.UTF-8"' >/etc/sysconfig/i18n source /etc/sysconfig/i18n echo $LANG
6、普通用户提权(mmod)
useradd mmod echo 123456|passwd --stdin mmod \cp /etc/sudoers /etc/sudoers.ori echo "mmod ALL=(ALL) NOPASSWD: ALL " >>/etc/sudoers tail -1 /etc/sudoers visudo -c
7、时间同步
echo '#time sync by mmod at 2015-2-1' >>/var/spool/cron/root echo '*/5 * * * * /usr/sbin/ntpdate time.nist.gov >/dev/null 2>&1' >>/var/spool/cron/root crontab -l 注:集群中有时间服务器,更改成时间服务器地址
8、命令行安全(选配)
设置闲置账号超时时间echo 'export TMOUT=300' >>/etc/profile命令行历史记录数 echo 'export HISTSIZE=5' >>/etc/profile echo 'export HISTFILESIZE=5' >>/etc/profile tail -3 /etc/profile ./etc/profile
9、加大文件描述
echo '* - nofile 65535' >>/etc/security/limits.conf tail -1 /etc/security/limits.conf
10、内核优化
cat >>/etc/sysctl.conf<<EOF net.ipv4.tcp_fin_timeout = 2 net.ipv4.tcp_tw_reuse = 1 net.ipv4.tcp_tw_recycle = 1 net.ipv4.tcp_syncookies = 1 net.ipv4.tcp_keepalive_time = 600 net.ipv4.ip_local_port_range = 4000 65000 net.ipv4.tcp_max_syn_backlog = 16384 net.ipv4.tcp_max_tw_buckets = 36000 net.ipv4.route.gc_timeout = 100 net.ipv4.tcp_syn_retries = 1 net.ipv4.tcp_synack_retries = 1 net.core.somaxconn = 16384 net.core.netdev_max_backlog = 16384 net.ipv4.tcp_max_orphans = 16384 #以下参数是对iptables防火墙的优化,防火墙不开会提示,可以忽略不理。 net.nf_conntrack_max = 25000000 net.netfilter.nf_conntrack_max = 25000000 net.netfilter.nf_conntrack_tcp_timeout_established = 180 net.netfilter.nf_conntrack_tcp_timeout_time_wait = 120 net.netfilter.nf_conntrack_tcp_timeout_close_wait = 60 net.netfilter.nf_conntrack_tcp_timeout_fin_wait = 120 EOF sysctl –p <<-配置完成后查看
11、下载安装基础软件
yum install lrzsz nmap tree dos2unix nc -y
12、定时清理邮件服务临时目录垃圾文件
centos 5版本 find /var/spool/clientmqueue/ -type f | xargs rm -f centos 6.x版本 find /var/spool/postfix/maildrop/ -type f | xargs rm -f 写成脚本,做定时任务 mkdir -p /server/scripts/ echo "find /var/spool/postfix/maildrop/ -type f | xargs rm -f " > /server/scripts/del_mailfile.sh echo "00 00 * * * /bin/bash /server/scripts/del_mailfile.sh > /dev/null 2>&1"
13、隐藏linux版本信息显示
[root@server1 ~]# > /etc/issue [root@server1 ~]# > /etc/issue.net [root@server1 ~]# cat /etc/issue.net [root@server1 ~]# cat /etc/issue
14、锁定关键系统文件,防止被提权篡改
chattr +i /etc/passwd /etc/shadow /etc/group /etc/gshadow /etc/inittab使用lsattr 进行查看,chattr -i进行解锁
15、为grub菜单加密
先利用/sbin/grub-md5-crypt 产生一个MD5密钥串,命令如下: [root@m01 ~]# /sbin/grub-md5-crypt Password: Retype password: $1$SQxvZ/$AXRHUbkNy9EkDHtmoEoQS0 修改grub.conf文件,命令如下: [root@m01 ~]# vim /etc/grub.conf # grub.conf generated by anaconda # # Note that you do not have to rerun grub after making changes to this file # NOTICE: You have a /boot partition. This means that # all kernel and initrd paths are relative to /boot/, eg. # root (hd0,0) # kernel /vmlinuz-version ro root=/dev/sda3 # initrd /initrd-[generic-]version.img #boot=/dev/sda default=0 timeout=5 splashimage=(hd0,0)/grub/splash.xpm.gz hiddenmenu passwd --md5 $1$SQxvZ/$AXRHUbkNy9EkDHtmoEoQS0 #注意:password要加在splashimage和title之间,否则无法生效 title CentOS 6 (2.6.32-696.el6.x86_64) root (hd0,0) kernel /vmlinuz-2.6.32-696.el6.x86_64 ro root=UUID=33ec961c-16e1-4234-bdbf-644bfdabf1eb rd_NO_LUKS KEYBOARDTYPE=pc KEYTABLE=us rd_NO_MD crashkernel=auto LANG=zh_CN.UTF-8 rd_NO_LV
16、禁止linux系统被ping(选配)
echo "net.ipv4.icmp_echo_ignore_all=1" >> /etc/sysctl.conf sysctl -p拓展:设置特定ip可以pingiptables -t filter -I INPUT -p icmp --icmp-type 8 -i eth0 -s 10.0.0.0/24 -j ACCEPT
17、升级具有典型漏洞
查看相关软件的版本号,命令如下: [root@m01 ~]# rpm -qa openssl openssh bash openssl-1.0.1e-57.el6.x86_64 bash-4.1.2-48.el6.x86_64 openssh-5.3p1-122.el6.x86_64 升级已知漏洞的软件版本到最新,命令如下: yum install openssl openssh bash -y
18、更改ssh服务端远程登录的配置
1 修改默认文件路径 2 vim /etc/ssh/sshd_config 3 4 修改的参数 5 port #端口 6 PermitEmptyPasswords #是否允许密码为空的用户远程登录 7 PermitRootLogin #是否允许root登录 8 UseDNS #指定sshd是否应该对远程主机名进行反向解析,以检查主机名是否与其IP地址真实对应。默认yes.建议改成no ,否则可能会导致SSH连接很慢。 9 GSSAPIAuthentication no #解决linux之间使用SSH远程连接慢的问题 10 ListenAddress #监听指定的IP地址 11 12 批量操作: 13 sed -ir '13 iPort 55666\nPermitRootLogin no\nPermitEmptyPasswords no\nUseDNS no\nGSSAPIAuthentication no' /etc/ssh/sshd_config