Linux 服务器运维笔记1：RedHat/CentOS 系统安装与基础配置

# M=Mebibytes, G=Gibibytes
# dd if=/dev/zero of=/swapfile bs=1M cout=2048
fallocate -l 2G /swapfile

# 权限
chmod 600 /swapfile

# 格式化
mkswap /swapfile

# 启用
swapon /swapfile

# 开机启用
vim /etc/fstab
/swapfile none swap defaults 0 0

# 删除
swapoff -a
rm -rf /swapfile

# 状态
swapon -s
free -m

# 设备UUID
lsblk -no UUID /dev/xxx

ssh-keygen -t rsa -b 4096 -C "wangyan"
mkdir ~/.ssh; vi ~/.ssh/authorized_keys
chmod 700 -R ~/.ssh && chmod 600 ~/.ssh/authorized_keys

-rw-r--r-- 1 root root    0 Mar  7 22:19 authorized_keys
-rw------- 1 root root 3243 Mar  7 22:46 id_rsa
-rw-r--r-- 1 root root  733 Mar  7 22:46 id_rsa.pub

vi /etc/ssh/sshd_config

#PermitRootLogin no
#PasswordAuthentication no
#AuthorizedKeysFile      .ssh/authorized_keys
#systemctl restart sshd.socket

cp /etc/sysconfig/network-scripts/ifcfg-em1 /etc/sysconfig/network-scripts/ifcfg-em1.bak

cat >/etc/sysconfig/network-scripts/ifcfg-em1<<-EOF
TYPE=Ethernet
BOOTPROTO=static
DEFROUTE=yes
IPV4_FAILURE_FATAL=no
NAME=em1
UUID=9ba3101c-ded9-4726-a533-de584cc28ed5
DEVICE=em1
ONBOOT=yes
IPADDR=192.168.10.246
PREFIX=24
NETMASK=255.255.255.0
GATEWAY=192.168.10.1
PEERDNS=no
DNS1=114.114.114.114
EOF

sysctl -w net.ipv6.conf.all.disable_ipv6=1.
sysctl -w net.ipv6.conf.default.disable_ipv6=1.

vi /etc/sysctl.conf

net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1

sysctl -p

cat >/usr/lib/sysctl.d/50-default.conf<<-EOF

# Disable IPv6
net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
EOF

sysctl -p

mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup

cat >/etc/yum.repos.d/CentOS7-Base-163.repo<<'EOF'
[base]
name=CentOS-$releasever - Base - 163.com
baseurl=http://mirrors.163.com/centos/$releasever/os/$basearch/
gpgcheck=1
gpgkey=http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-7

[updates]
name=CentOS-$releasever - Updates - 163.com
baseurl=http://mirrors.163.com/centos/$releasever/updates/$basearch/
gpgcheck=1
gpgkey=http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-7

[extras]
name=CentOS-$releasever - Extras - 163.com
baseurl=http://mirrors.163.com/centos/$releasever/extras/$basearch/
gpgcheck=1
gpgkey=http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-7

[centosplus]
name=CentOS-$releasever - Plus - 163.com
baseurl=http://mirrors.163.com/centos/$releasever/centosplus/$basearch/
gpgcheck=1
enabled=0
gpgkey=http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-7
EOF

rpm -qa |grep yum

# args可以将输入内容（通常通过命令行管道传递），转成后续命令的参数
# -I '{}'表示将后面命令行的{}替换成前面解析出来的参数
rpm -aq|grep yum|xargs -t -I '{}' rpm -e {} --nodeps
rpm -qa |grep yum 

whereis yum
mv /etc/yum /etc/yum.rhel

rpm -ivh *
rpm -qa |grep yum 

touch /etc/yum/pluginconf.d/{product-id.conf,search-disabled-repos.conf,subscription-manager.conf}

cat >/etc/yum.repos.d/CentOS7-Base-163.repo<<'EOF'
[base]
name=CentOS-7 - Base - 163.com
baseurl=http://mirrors.163.com/centos/7/os/$basearch/
gpgcheck=1
gpgkey=http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-7

[updates]
name=CentOS-7 - Updates - 163.com
baseurl=http://mirrors.163.com/centos/7/updates/$basearch/
gpgcheck=1
gpgkey=http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-7

[extras]
name=CentOS-7 - Extras - 163.com
baseurl=http://mirrors.163.com/centos/7/extras/$basearch/
gpgcheck=1
gpgkey=http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-7

[centosplus]
name=CentOS-7 - Plus - 163.com
baseurl=http://mirrors.163.com/centos/7/centosplus/$basearch/
gpgcheck=1
enabled=0
gpgkey=http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-7
EOF

curl -o /etc/yum.repos.d/CentOS7-Base-163.repo http://mirrors.163.com/.help/CentOS7-Base-163.repo
sed -i "s|\$releasever|7|i" /etc/yum.repos.d/CentOS7-Base-163.repo

yum install -y epel-release

rpm -Uvh https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm

yum clean all && yum makecache

hostnamectl status
hostnamectl set-hostname s1

yum -y install vim curl wget net-tools kernel-headers

# 当前内核
# Linux 3.10.0-514.el7.x86_64
uname -rs

# 发行版
#CentOS Linux release 7.3.1611 (Core)
cat /etc/centos-release

# 排除内核和系统版本更新
vim /etc/yum.conf
exclude=kernel* centos-release* redhat-release* 

systemctl stop firewalld.service && \
systemctl disable firewalld.service

yum install ntp -y && \
timedatectl set-timezone Asia/Shanghai && \
timedatectl set-ntp yes && \
systemctl enable ntpd.service && \
systemctl start ntpd.service

vim /etc/selinux/config

SELINUX=disabled

# bash 级限制 
ulimit -n 1000000

# 用户级限制
* soft nofile 1000001
* hard nofile 1000002
root soft nofile 1000001
root hard nofile 1000002

# 系统级限制
cat /proc/sys/fs/file-max

netstat -tulpn # 查看
yum remove package_name # 删除

systemctl stop postfix.service  && \
systemctl disable postfix.service

yum -y update