CentOS7 系统基础优化

Posted 2020-10-22

1.网卡给成eth0
cd /etc/sysconfig/network-scripts/

vim ifcfg-eno16777729
TYPE=Ethernet
BOOTPROTO=static
IPADDR=192.168.1.201
NETMASK=255.255.255.0
GATEWAY=192.168.1.1
DEFROUTE=yes
PEERDNS=yes
PEERROUTES=yes
IPV4_FAILURE_FATAL=no
NAME=eth0
UUID=efd17b9a-a5ab-4c94-be62-d2c32eb48a7e
DEVICE=eth0
ONBOOT=yes
DNS1=202.106.0.20

mv ifcfg-eno16777729 ifcfg-eth0
vi /etc/sysconfig/grub
GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR="$(sed ‘s, release .*$,,g‘ /etc/system-release)"
GRUB_DEFAULT=saved
GRUB_DISABLE_SUBMENU=true
GRUB_TERMINAL_OUTPUT="console"
GRUB_CMDLINE_LINUX="net.ifnames=0 biosdevname=0 rhgb quiet" #添加 net.ifnames=0 biosdevname=0
GRUB_DISABLE_RECOVERY="true"

grub2-mkconfig -o /boot/grub2/grub.cfg #生成启动菜单
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-3.10.0-327.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-327.el7.x86_64.img
Found linux image: /boot/vmlinuz-0-rescue-e8675ae79abd41309dac42388f8d9116
Found initrd image: /boot/initramfs-0-rescue-e8675ae79abd41309dac42388f8d9116.img
reboot

ip addr 或者
yum install net-tools #默认centos7不支持ifconfig 需要看装net-tools包
ifconfig eth0 #在次查看网卡信息

2.更新系统： yum update -y
3.给 /etc/rc.d/rc.local 添加执行权限
[[email protected] ~]# ll /etc/rc.local
lrwxrwxrwx. 1 root root 13 Feb 6 07:28 /etc/rc.local -> rc.d/rc.local
[[email protected] ~]# ll /etc/rc.d/rc.local
-rw-r--r--. 1 root root 473 May 12 2016 /etc/rc.d/rc.local
[[email protected] ~]# chmod +x /etc/rc.d/rc.local\

4.添加用户
[[email protected] ~]# useradd hequan
[[email protected] ~]# echo 123456 | passwd --stdin hequan
Changing password for user hequan.
passwd: all authentication tokens updated successfully.
[[email protected] ~]# usermod -G wheel hequan
[[email protected] ~]# sed -i ‘6s/^#//g‘ /etc/pam.d/su
[[email protected] ~]# grep wheel /etc/pam.d/su #只有WHEEL组的可以su # Uncomment the following line to implicitly trust users in the "wheel" group.
#auth sufficient pam_wheel.so trust use_uid # Uncomment the following line to require a user to be in the "wheel" group.
auth required pam_wheel.so use_uid
扩展:为用户hequan添加sudo，除关机外的其他所有操作：

[[email protected] ~]# visudo
Cmnd_Alias SHUTDOWN = /sbin/halt, /sbin/shutdown, /sbin/poweroff, /sbin/reboot, /sbin/init
hequan ALL=(ALL) ALL,!SHUTDOWN
%wheel ALL=(ALL) ALL,!SHUTDOWN #修改
Defaults logfile=/var/log/sudo.log
5.禁用selinux
[[email protected] ~]# grep -i ^selinux /etc/selinux/config
SELINUX=enforcing
SELINUXTYPE=targeted
[[email protected] ~]# sed -i ‘/^SELINUX/s/enforcing/disabled/g‘ /etc/selinux/config
[[email protected] ~]# grep -i ^selinux /etc/selinux/config
SELINUX=disabled
SELINUXTYPE=targeted
[[email protected] ~]# getenforce
Enforcing
[[email protected] ~]# reboot
6.关闭防火墙
操作系统环境：CentOS Linux release 7.0.1406(Core) 64位
CentOS 7.0默认使用的是firewall作为防火墙，这里改为iptables防火墙步骤。

1、关闭firewall：
systemctl stop firewalld.service #停止firewall
systemctl disable firewalld.service #禁止firewall开机启动
firewall-cmd --state #查看默认防火墙状态（关闭后显示notrunning，开启后显示running）

2、iptables防火墙（这里iptables已经安装，下面进行配置，如果没安装：yum -y install iptables-services）
vi/etc/sysconfig/iptables #编辑防火墙配置文件 # sampleconfiguration for iptables service # you can edit thismanually or use system-config-firewall # please do not askus to add additional ports/services to this default configuration
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT[0:0]
:OUTPUT ACCEPT[0:0]
-A INPUT -m state--state RELATED,ESTABLISHED -j ACCEPT
-A INPUT -p icmp -jACCEPT
-A INPUT -i lo -jACCEPT
-A INPUT -p tcp -mstate --state NEW -m tcp --dport 22 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 80 -jACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 8080-j ACCEPT
-A INPUT -j REJECT--reject-with icmp-host-prohibited
-A FORWARD -jREJECT --reject-with icmp-host-prohibited
COMMIT
:wq! #保存退出

备注：这里使用80和8080端口为例。***部分一般添加到“-A INPUT -p tcp -m state --state NEW -m tcp--dport 22 -j ACCEPT”行的上面或者下面，切记不要添加到最后一行，否则防火墙重启后不生效。
systemctlrestart iptables.service #最后重启防火墙使配置生效
systemctlenable iptables.service #设置防火墙开机启动

7.修改主机名：
[[email protected] ~]# hostnamectl set-hostname hequan.com
[[email protected] ~]# hostname
hequan.com

8.查看并管理服务
[[email protected] ~]# systemctl -t service
[[email protected] ~]# systemctl list-unit-files -t service

9 设置字符集

[[email protected] ~]# echo $LANG
zh_CN.UTF-8
[[email protected] ~]# vi /etc/locale.conf
LANG="en_US.UTF-8"
[[email protected] ~]# source /etc/locale.conf

10.配置在线yum (同6一样)
11.配置ssh
sed -i -e ‘49s/^#//g‘ /etc/ssh/sshd_config ##启用49行配置
sed -i -e ‘49s/yes/no/g‘ /etc/ssh/sshd_config ##禁止root使用ssh登录
sed -i -e ‘129s/#/ /g‘ /etc/ssh/sshd_config ##禁止UseDNS
sed -i -e ‘129s/yes$/no/g‘ /etc/ssh/sshd_config
sed -i ‘/^GSS/s/yes/no/g‘ /etc/ssh/sshd_config ##禁用GSSAPI认证加快登录速度
systemctl restart sshd ##重新启动服务
systemctl enable sshd ##设置为开机启动
systemctl status sshd ##查看状态
● sshd.service - OpenSSH server daemon
Loaded: loaded (/usr/lib/systemd/system/sshd.service; enabled; vendor preset: enabled)
Active: active (running) since 一 2016-06-06 00:16:26 CST; 1min 3s ago

12 .加大文件描述符数量

ulimit -SHn 1024000
echo "ulimit -SHn 1024000" >> /etc/rc.d/rc.local
source /etc/rc.d/rc.local

总结：
a.所有进程打开的文件描述符数不能超过/proc/sys/fs/file-max
b.单个进程打开的文件描述符数不能超过user limit中nofile的soft limit(/etc/security/limits.conf)
c.nofile的soft limit不能超过其hard limit
d.nofile的hard limit不能超过/proc/sys/fs/nr_open

13.优化内核
cat /etc/sysctl.conf
#CTCDN系统优化参数
#关闭ipv6
net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
#决定检查过期多久邻居条目
net.ipv4.neigh.default.gc_stale_time=120
#使用arp_announce / arp_ignore解决ARP映射问题
net.ipv4.conf.default.arp_announce = 2
net.ipv4.conf.all.arp_announce=2
net.ipv4.conf.lo.arp_announce=2 # 避免放大攻击
net.ipv4.icmp_echo_ignore_broadcasts = 1 # 开启恶意icmp错误消息保护
net.ipv4.icmp_ignore_bogus_error_responses = 1
#关闭路由转发
net.ipv4.ip_forward = 0
net.ipv4.conf.all.send_redirects = 0
net.ipv4.conf.default.send_redirects = 0
#开启反向路径过滤
net.ipv4.conf.all.rp_filter = 1
net.ipv4.conf.default.rp_filter = 1
#处理无源路由的包
net.ipv4.conf.all.accept_source_route = 0
net.ipv4.conf.default.accept_source_route = 0
#关闭sysrq功能
kernel.sysrq = 0
#core文件名中添加pid作为扩展名
kernel.core_uses_pid = 1 # 开启SYN洪水攻击保护
net.ipv4.tcp_syncookies = 1
#修改消息队列长度
kernel.msgmnb = 65536
kernel.msgmax = 65536
#设置最大内存共享段大小bytes
kernel.shmmax = 68719476736
kernel.shmall = 4294967296
#timewait的数量，默认180000
net.ipv4.tcp_max_tw_buckets = 6000
net.ipv4.tcp_sack = 1
net.ipv4.tcp_window_scaling = 1
net.ipv4.tcp_rmem = 4096 87380 4194304
net.ipv4.tcp_wmem = 4096 16384 4194304
net.core.wmem_default = 8388608
net.core.rmem_default = 8388608
net.core.rmem_max = 16777216
net.core.wmem_max = 16777216
#每个网络接口接收数据包的速率比内核处理这些包的速率快时，允许送到队列的数据包的最大数目
net.core.netdev_max_backlog = 262144
#限制仅仅是为了防止简单的DoS 攻击
net.ipv4.tcp_max_orphans = 3276800
#未收到客户端确认信息的连接请求的最大值
net.ipv4.tcp_max_syn_backlog = 262144
net.ipv4.tcp_timestamps = 0
#内核放弃建立连接之前发送SYNACK 包的数量
net.ipv4.tcp_synack_retries = 1
#内核放弃建立连接之前发送SYN 包的数量
net.ipv4.tcp_syn_retries = 1
#启用timewait 快速回收
net.ipv4.tcp_tw_recycle = 1
#开启重用。允许将TIME-WAIT sockets 重新用于新的TCP 连接
net.ipv4.tcp_tw_reuse = 1
net.ipv4.tcp_mem = 94500000 915000000 927000000
net.ipv4.tcp_fin_timeout = 1
#当keepalive 起用的时候，TCP 发送keepalive 消息的频度。缺省是2 小时
net.ipv4.tcp_keepalive_time = 1800
net.ipv4.tcp_keepalive_probes = 3
net.ipv4.tcp_keepalive_intvl = 15
#允许系统打开的端口范围
net.ipv4.ip_local_port_range = 1024 65000
#修改防火墙表大小，默认65536
net.netfilter.nf_conntrack_max=655350
net.netfilter.nf_conntrack_tcp_timeout_established=1200 # 确保无人能修改路由表
net.ipv4.conf.all.accept_redirects = 0
net.ipv4.conf.default.accept_redirects = 0
net.ipv4.conf.all.secure_redirects = 0
net.ipv4.conf.default.secure_redirects = 0
本文出自 “兰芷” 博客，请务必保留此出处http://7826443.blog.51cto.com/7816443/1775248
sysctl -p #生效

14.时间设置
yum install chrony
vi /etc/chrony.conf
1 server 0.centos.pool.ntp.org
2 server 3.europe.pool.ntp.org
systemctl enable chronyd.service
systemctl start chronyd.service
timedatectl set-timezone Asia/Shanghai
timedatectl set-time "2015-01-21 11:50:00"（可以只修改其中一个）修改日期时间
timedatectl 查看时间状态
chronyc sources -v 查看时间同步源
chronyc sourcestats -v