Centos Foundation and Installation

Centos Foundation and Installation

Centos installation

1. Linux version derivation

|- AT&T Unix: AT&T was originally developed, and later set up Bell Laboratory with Western Electric Company to continue to develop Unix from UNIX to UNICS (UNiplexed Information and Computing Service), while unics Brian Kernighan is a tease to Multiplexed Information and Computing Service.
  |- Unix: Closed Source, R&D developer Bell Laboratory, acquired by Nokia in April 2015, is now the R&D Department of Nokia.  
    |- Berkeley Software Distribution (BSD) Open Source: unix Version released by the University of California, Berkeley
      |- Jolix | 386BSD: William Jolitz, Lynne Jolitz, University of California, Berkeley
        |-NetBSD:        The NetBSD Foundation
          |- OpenBSD: The OpenBSD Project, developed from NetBSD Forked, contributes mainly to OpenSSH
      |- FreeBSD: The FreeBSD Project, based on the 1992 release version of BSD, was redeveloped due to disapproval of the future research and development plan for 386BSD.
        |- Darwin: Apple Inc's Open Source Operating System
          |- MacOS: Apple Inc's closed-source operating system, Macintosh, originated from an Apple called McIntosh, and I don't know if it was Jobs who intentionally or unintentionally misspelled it.
    |- Linux, Open Source Implementation of Unix (GPL), but not based on Unix code
      |- Debian (a combination of the names of Ian Murdock, the founder of Debian, and his wife Debra)
        |- Red Hat Linux(RHL) Open Source
          |- Red Hat Enterprise Linux(RHEL) Closed Source           
          |- CentOS (Community Enterprise Operating System) Centos does not have its own kernel and uses the redhat kernel
          |- Oracle Linux (Oracle means oracle, because CIA wants this software system to guide them like oracle, quickly find the information they need, Oracle first developed information management software for CIA)
        |- Ubuntu: Canonical Ltd., Ubuntu community (named "ubuntu" from Zulu or Hausa in southern Africa, which means "human nature" and "my existence is due to the existence of all", is a traditional African value, similar to the "benevolence" thought of Chinese society. )
      |- SUSE Linux (meaning "Software-und System-Entwicklung" is a German sentence, English is "Software and system development")
      |-Linux Router Project 
        |-LEAF (Linux Embedded Appliance Framework Project)
          |-Alpine Linux 
      |- linksys GPL (estimated based on the linux kernel)
        |- OpenWrt (Open Wireless Router), originally named for Linksys WRT54G Wi-Fi routers, is currently merged with (LED E) Linux Embedded Development Environment
        |- DD-WRT (Open Wireless Router), 
      |- The Android kernel uses GPL linux and BSD libc for authorization segmentation
      |- PhotonOS (Vmware Lightweight Operating System for Container Development)

Bell Labs AT&T Bell Laboratories | Bell Telephone Laboratories | Bell Labs | Nokia Bell Labs

1925 year Western Electric Research Laboratories and American Telephone & Telegraph company Some of the engineering departments have assembled Bell Laboratories, and the two companies share ownership equally.

SSH Available Pre-Configuration

  1. Modify the network card name and disable ipv6
    Modify the / etc/sysconfig/network-scripts/ifcfg-e***file

Rename the file / etc/sysconfig/network-scripts/ifcfg-e*** to ifcfg-eth0
Modify the GRUBCMDLINELINUX variable in the / etc/default/grub file

net.ifnames=0 biosdevname=0 ipv6.disable=1

Run command

grub2-mkconfig -o /boot/grub2/grub.cfg

Close the firewall (later to develop 22 ports and icmp protocol)

systemctl stop firewalld
systemctl disable firewalld
  1. Setting static IP
    Modify the / etc/sysconfig/network-scripts/ifcfg-eth0 file
#DNS1(DNS can be configured globally)

Password login SSH configuration other options

  1. Setting DNS/etc/resolv.conf
  1. Install wget (Docker container recommended curl instead)
yum install wget
  • yum source configuration
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
yum makecache

Non-Ali Cloud Intranet Host
Modify the / etc/yum.repos.d/CentOS-Base.repo file
Delete all links with aliyuncs.com

  1. Upgrade the latest system
    yum update
  2. Editor VIM Installation
    yum -y install vim-enhanced telnet
  3. Close and disable firewalls
    (Temporary solution, firewall filtering rules should be set)
    systemctl stop firewalld
    systemctl disable firewalld
  4. System Language Configuration
    Function to prevent Chinese scrambling on various platforms
    View the current system code

View System Installed Codes

locale -a

Language Coding Switching
Compile / etc/profile file and add code at the end of the file

export LANG=en_US.UTF-8
  1. Time Server Configuration
    Inspection of installation
rpm -q ntp


yum -y install ntp
systemctl enable ntpd
systemctl start ntpd

Manual Time Synchronization

ntpdate -u ntp1.aliyun.com
clock -w(Write hardware CMOS Otherwise, restart will be restored)
  • time zone
  • Time zone view
    date -R
    TZ='Asia/Shanghai'; export TZ added to / etc/profile
    Timedatectl set timezone Asia / Shanghai
    Aliyun NTP Server

Another method, chrony(centos7)
chronyc sourcestats && systemctl is-enabled ntpd && systemctl is-enabled chronyd

  1. SSH login key generation and configuration
    Key generation
ssh-keygen -t rsa

Copy the pubkey of the authorized logged-in user to the authorzied_keys file of the server


Ensure authorized_keys file permissions are 600 (otherwise connections will be rejected and logs are unrecorded)
User login welcome word configuration modification/etc/motd file
Fault troubleshooting method/usr/sbin/sshd-d debugging mode start-up log
Local virtual machine Welcome to SherryBlue.Org Virtual Host!
Cloud server Welcome to SherryBlue.Org @ Aliyun Elastic Compute Service!

  1. Setting Host Name
hostnamectl set-hostname docker1

Automatic Configuration Script

#1.DNS configuration
echo "nameserver" >> /etc/resolv.conf
echo "nameserver" >> /etc/resolv.conf
#2.yum source configuration
yum -y install wget
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
sed -i '/aliyuncs.com/d' /etc/yum.repos.d/CentOS-Base.repo 
yum clean metadata
yum makecache
yum -y update
# Install epel Ali Cloud Source
wget -P /etc/yum.repos.d/ http://mirrors.aliyun.com/repo/epel-7.repo
yum clean all
yum makecache
#3. Environmental variable settings
echo "export LANG=en_US.UTF-8" >> /etc/profile #Code
echo "export TZ='Asia/Shanghai'" >> /etc/profile #time zone
echo "MYDOCKER_HOME=/data;export MYDOCKER_HOME" >> /etc/profile #Docker
echo "export PATH=\$PATH:\$MYDOCKER_HOME/docker-file/bin" >> /etc/profile
echo "DOCKER_REGISTRY=registry-vpc.cn-hangzhou.aliyuncs.com/lineto; export DOCKER_REGISTRY" >> /etc/profile
source /etc/profile
#4. Time zone and clock
timedatectl set-timezone Asia/Shanghai
yum -y install ntpdate
ntpdate ntp1.aliyun.com
clock -w
#5.SSH key login configuration
sed -i 's/#UseDNS yes/UseDNS no/g' /etc/ssh/sshd_config
sed -i 's/#PubkeyAuthentication/PubkeyAuthentication/g' /etc/ssh/sshd_config
sed -i 's/PasswordAuthentication yes/PasswordAuthentication no/g' /etc/ssh/sshd_config
mkdir -p /root/.ssh/
echo "ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQCjDQ6Ss/R65zPsdzGndM2qroAWHFuJ2LvxD3oLj9VIpGLqj1SfKTvLmUvDnG2kqD4P8lWjn9UiyYgYj3tLzxCRT1/QYW/R1a5NrpM2aAiZ6lVueeQ4anj2FRWqczEnxp+pidGh6vXF4dnE68am9A+/SDbsnu8UIZb2rxEfNp2W0t8WJQ5bTZtFHBmsa8/HCwX+DS8VABMgYJjWFExrO+qVejjUj8pz6QtOriQE7YT3s3pHXC4lt4usVcwB1SYTNrpgf1wrhDr7vSvOB7YPJAPQ1pCFXu+V3GfRkFoRJwZGqg4hSBheV9y66megsTriFMWYEjZR2tBT+dcmTtyFRwBd blue@blue.sherryblue.org" >> /root/.ssh/authorized_keys
service sshd restart
#6. Turn off SELinux (in some cases, SELinux can cause permission problems such as file reading failure)
setenforce 0 
sed -i 's/SELINUX=enforcing/SELINUX=disabled/g' /etc/selinux/config
#7. Installation of firewall services (many times we need address mapping, this command is very convenient)
yum -y install iptables-services
#8. Close the postfix service (port 25)
systemctl stop postfix #Need to open again by mail
systemctl disable postfix
#09. Memory and SWAP optimization
sysctl vm.swappiness=0 #Priority for using physical RAM as detailed in the Performance Test Memory section
echo "vm.swappiness = 0" >> /etc/sysctl.conf
#10. Host name configuration
hostnamectl set-hostname mesos-master

crontab -e

  • */1 * * * /usr/sbin/ntpdate ntp.d.com

Other common debugging tools

yum install lsof # Total download size: 331 k Installed size: 927 k
yum install iotop (process-level hard disk and network io read-write monitoring)
yum install sysstat (system monitoring tools, iostat, etc.)
yum install traceroute
yum install hdparm

iperf rpm Packet Installed size: 181 k (Bandwidth Check)

Kernel parameters (to be tested)

hung_task_timeout_secs error in some cases

Sep 24 08:44:54 docker75 kernel: INFO: task nfsd:413 blocked for more than 120 seconds.
Sep 24 08:44:54 docker75 kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.

Centos Kernel Upgrade

Tsinghua Mirror https://mirrors.tuna.tsinghua.edu.cn/elrepo/

#Installing Kernel Sources
rpm -Uvh https://mirrors.tuna.tsinghua.edu.cn/elrepo/kernel/el7/x86_64/RPMS/elrepo-release-7.0-2.el7.elrepo.noarch.rpm
#View the supported mainline version
yum --enablerepo=elrepo-kernel list  kernel-ml-devel kernel-ml --showduplicates
#Install the latest mainline version of the kernel
yum --enablerepo=elrepo-kernel install kernel-ml-devel kernel-ml -y
#Install the latest longtern version of the kernel
yum --enablerepo=elrepo-kernel list  kernel-lt-devel kernel-lt --showduplicates

Initialization Process of Virtual Machine on H3C CAS Platform

Setting CD-ROM Priority Start
 Install centos operating system
 Install CATools
 Close and disable firewalls
systemctl stop firewalld.service
systemctl disable firewalld.service
 Install Blue Whale Client
 Server Initialization Configuration Using Blue Whale
 Install System Monitoring Client

Keywords: yum CentOS ssh Linux

Added by tc1 on Wed, 25 Sep 2019 15:18:46 +0300