ubuntu1604系统初始化

1.初始化网络配置

1.1.创建工作目录

• 生产环境下必须有个固定的目录存放一些安装软件和调试工具，
• 否则每个管理员都随意存放软件工具，服务器的环境可以想而知

mkdir -p /opt/{tools,scripts}
mkdir -p /data/backup
cd /opt/tools/

• 安装常用软件工具

apt-get update
apt-get install lrzsz vim wget curl lsof telnet net-tools ntpdate tree screen iotop iftop 

1.2.设置主机名和hosts解析

• 修改服务器主机名

hostname demosrv-01
vi /etc/hostname 
--------------------------------
demosrv-01
-------------------------------

• 设置hosts域名解析

vi /etc/hosts
--------------------------------
192.168.1.200    demosrv-01
--------------------------------

1.3.设置固定IP地址和DNS域名解析

1.3.1.修改主机IP

• 1）为网卡配置静态IP地址

sudo vim /etc/network/interfaces
--------------------------------------------
auto eth0
iface eth0 inet static
address 192.168.1.200
netmask 255.255.255.0
gateway 192.168.1.1
dns-nameservers 223.5.5.5
dns-nameservers 8.8.8.8
--------------------------------------------
# 重启网卡
sudo /etc/init.d/networking restart

• 2）设定第二个IP地址(虚拟IP地址)

sudo vim /etc/network/interfaces
--------------------------------------------
auto eth0:1
iface eth0:1 inet static
address 192.168.1.201
netmask 255.255.255.0
gateway x.x.x.x
network x.x.x.x
broadcast x.x.x.x
--------------------------------------------
# 重启网卡：
sudo /etc/init.d/networking restart

1.3.2.设置DNS解析

vi /etc/resolv.conf 
--------------------------------
nameserver 202.106.0.20
nameserver 8.8.8.8
--------------------------------
ip add
ping www.baidu.com

1.4.配置 apt 源（阿里云）

1.4.1.备份原始 apt 源配置文件

cp /etc/apt/sources.list /etc/apt/sources.list.ori

1.4.2.修改 apt 源配置文件（更换 apt 源）

vim /etc/apt/sources.list
----------------------------------
# aliyun
deb http://mirrors.aliyun.com/ubuntu/ xenial main
deb-src http://mirrors.aliyun.com/ubuntu/ xenial main

deb http://mirrors.aliyun.com/ubuntu/ xenial-updates main
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-updates main

deb http://mirrors.aliyun.com/ubuntu/ xenial universe
deb-src http://mirrors.aliyun.com/ubuntu/ xenial universe
deb http://mirrors.aliyun.com/ubuntu/ xenial-updates universe
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-updates universe

deb http://mirrors.aliyun.com/ubuntu/ xenial-security main
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-security main
deb http://mirrors.aliyun.com/ubuntu/ xenial-security universe
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-security universe
----------------------------------

1.4.3.更新源和软件版本

apt-get update
apt-get upgrade

1.4.4.复损坏的软件包

# 尝试卸载出错的包，重新安装正确版本的
sudo apt-get -f install

2.配置系统环境变量

2.1.修改记录的历史命令数量

echo "HISTSIZE=10000" >> /etc/profile
tail -1 /etc/profile

2.2.设置超时自动注销登陆

# 8h=28800s
echo " " >> /etc/profile
echo "# Auto-Logout for 4 hours by zhaoshuai on $(date +%F)." >> /etc/profile
echo "export TMOUT=28800" >> /etc/profile
tail -3 /etc/profile
source /etc/profile
echo $TMOUT

3.配置系统安全选项

3.1.修改 ssh 服务配置

• 只监听IPv4端口，关闭GSSAPI秘钥认证，关闭DNS解析加速ssh连接

• 手动修改配置文件

vim /etc/ssh/sshd_config
-----------------------------
ListenAddress 0.0.0.0
PasswordAuthentication no
GSSAPIAuthentication no
UseDNS no
-----------------------------

• 命令行修改

echo "ListenAddress 0.0.0.0" >> /etc/ssh/sshd_config
echo "GSSAPIAuthentication no" >> /etc/ssh/sshd_config
echo "UseDNS no" >> /etc/ssh/sshd_config

grep ListenAddress /etc/ssh/sshd_config
grep GSSAPIAuthentication /etc/ssh/sshd_config
grep UseDNS /etc/ssh/sshd_config

• 重启sshd服务

/bin/systemctl restart  sshd.service
/bin/systemctl status  sshd.service

3.2.关闭 selinux

• 不需要

3.3.关闭防火墙

• 内网一般不需要使用防火墙

systemctl stop firewalld
systemctl disable firewalld
systemctl status  firewalld

3.4.关闭其他不用的服务

• 邮箱服务，CentOS7默认安装postfix，而不是sendmail

systemctl stop  postfix
systemctl disable  postfix
systemctl status  postfix
netstat -anptl

4.修改内核参数

4.1.修改文件句柄数

vim /etc/security/limits.conf 
-----------------------------------
# 系统最大连接数
*    soft    nofile    65535
*    hard   nofile    65535
*    soft    nproc    65535
*    hard   nproc    65535
-----------------------------------

4.2.配置 TIME_WAIT 参数

• 清理 TIME_WAIT 状态的连接

netstat -anptl|grep TIME_WAIT|wc -l
echo " " >> /etc/sysctl.conf
echo "# made by zhaoshuai for kill time_wait on $(date +%F)." >> /etc/sysctl.conf
echo "net.ipv4.tcp_syncookies = 1" >> /etc/sysctl.conf
echo "net.ipv4.tcp_tw_reuse = 1" >> /etc/sysctl.conf
echo "net.ipv4.tcp_tw_recycle = 1" >> /etc/sysctl.conf
echo "net.ipv4.tcp_fin_timeout = 30" >> /etc/sysctl.conf
echo "net.ipv4.tcp_orphan_retries = 2" >> /etc/sysctl.conf
echo "net.ipv4.ip_local_port_range = 1024 65000" >> /etc/sysctl.conf
tail -8 /etc/sysctl.conf
sysctl -p 
netstat -anptl|grep TIME_WAIT|wc -l

4.3.让系统自动回收缓存 cache

echo " ">>/etc/sysctl.conf
echo "# Automatic recovery memory on $(date +%F)">>/etc/sysctl.conf
echo "vm.extra_free_kbytes=209196">>/etc/sysctl.conf
sysctl -p

5.配置时间同步

• 安装ntp服务并配置开机自启动

yum -y install ntp
systemctl enable ntpd
systemctl start ntpd
systemctl status ntpd

• 手动进行时间同步

date
/usr/sbin/ntpdate ntp1.aliyun.com

• 配置自动同步时间

echo "# made by zhaoshuai for sync time on $(date +%F)" >> /var/spool/cron/crontabs/root
echo '*/5 * * * * /usr/sbin/ntpdate ntp1.aliyun.com > /dev/null 2>&1' >> /var/spool/cron/crontabs/root
crontab -l

• 注意：

时区应该为CST为中部时区，如果是EST则为东部时区
安装CentOS系统时要去掉夏令时的选项，否则在夏令时的那一天会有时间的自动变换，
如果某个服务在时间上有要求就会导致该服务承载的业务出现问题，所以要关闭夏令时

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