1. Network configuration under Linux

Posted by DJ Unique on Fri, 14 Jan 2022 07:11:05 +0100

Network configuration under Linux


Full name: internet protocol address

ipv4----------internet protocol version 4

ip is composed of 32 01s

11111110.11111110.11111110.11111110 =

Subnet mask

Used to divide the network area

The number on the ip corresponding to the non-0 bit of the subnet mask represents the network bit of this ip

The number corresponding to bit 0 of the subnet mask is the host bit of the ip

The network bit represents the network area

The host bit represents a host in the network area

ip communication decision

Can two IP S with the same network bit and inconsistent host bit communicate directly

For example: host 1: / 24 =

Host 2:

The two hosts can communicate directly

Network settings tool

ping										#Check whether the network is unobstructed
ping -c 1									#Ping once 	 c means count
ping -w 1									#Wait 1 second 	 w stands for wait
ping -c1 -w1 ip								#ping1 time, wait 1 second
ifconfig	#View or set network interface
ifconfig									#see
ifconfig device ip/24						#set up
ifconfig device down						#close
ifconfig device up							#open
ip addr		#Detect or this network interface
ip addr show								#testing
ip addr add ip/24 dev device				#set up
ip addr del dev ens160 ip/24				#delete

Graphic mode setting ip

  1. nm-connection-editor

    Make the setting effective after setting

    nmcli connection show
    nmcli connection reload
    nmcli connection down song
    nmcli connection up song

    It is not recommended to use systemctl to control the network, as follows:

    systemctl restart NetworkManager
  2. nmtui

Command mode setting network

nmcli		#The NetworkManager service must be turned on
nmcli device connect ens4					#Enable ens4 network card
nmcli device disconnect ens4				#Turn off the ens4 network card
nmcli device show ens4						#View network card information
nmcli device show ens4						#View network card service interface information
nmcli connection show						#View connections
nmcli connection down song					#Close connection
nmcli connection up song					#Open connection
nmcli connection delete song				#Delete connection
nmcli connection reload						#Restart connection

add connections

nmcli connetion add type ethernet ifname ens4 con-name song ipv4.method manual ipv4.addresses


nmcli connetion modify song ipv4.addresses

Manage network profiles

Network configuration file path: / etc / sysconfig / network scripts/

Configuration file naming format ifcfg-****

Profile configuration rules

vim ifcfg-****
DEVICE=*** 										#Equipment name
BOOTPROTO=dhcp|static|none 						#Equipment working mode
ONBOOT=yes 										#Automatically activate the network card when the network service is turned on
IPADDR= 										#IP address
PREFIX=24 										#Subnet mask
NETMASK= 							#Subnet mask
NAME= 											#Interface name
#If you want to configure mult ip le IPS on a network card, then:
IPADDR0= 										#IP address
NETMASK0= 							#Subnet mask
IPADDR1= 										#IP address
NETMASK1= 							#Subnet mask

Set dhcp

vim ifcfg-ens4
DEVICE=ens4 									#Equipment name
BOOTPROTO=dhcp									#Equipment working mode
ONBOOT=yes 										#Automatically activate the network card when the network service is turned on
systemctl restart network

lo loop interface

The loopback interface is equivalent to the human nerve and is used for internal signal transmission. The ip is, which is generally called localhost


There are two ways to set the gateway:

  1. Enable global gateway ---- it takes effect for all network cards without a gateway

    Edit the system configuration file / etc/sysconfig/network

    Add gateway GATEWAY= in the configuration file

  2. Modify the network configuration file / etc / sysconfig / network scripts / ifcfg-****

    vim /etc/sysconfig/network-scripts/ifcfg-****
    #Add gateway configuration information under the configuration file
    #If there are multiple IPS in the network card settings, specify which ip is effective

View gateway information

route -n										#View gateway information


DNS(Domain Name Server) = = domain name resolution service

Users are sensitive to characters and computers are sensitive to numbers. When the user enters the website Baidu COM, this web address is not an IP address that can communicate

Address, and need to put Baidu in the system Com becomes the ip address of Baidu server. This process is called address resolution

  1. Address resolution is directly provided in the local resolution file / etc/hosts, but it needs to be manually edited one by one, which is time-consuming and laborious

    vim /etc/hosts
    ************************************************************************		baidu.com
  2. DNS points to the file / etc / resolv Conf, which takes effect immediately without restarting the network

    echo nameserver=	>/etc/resolv.conf
  3. To configure DNS in the network configuration file, restart the network to take effect. When the network restarts, this parameter will modify / etc / resolv conf

    vim /etc/sysconfig/network-scripts/ifcfg-xxxx
    #Add DNS to profile

Note: when the network working mode is dhcp, the system will automatically obtain ip, gateway and dns, mostly in / etc / resolv Conf will be modified by the obtained dns information. If you do not need to obtain dns information, you need to add PEERDNS=no in the network card configuration file / etc / sysconfig / network scripts / ifcfg - * * * *

Set resolution priority

The system defaults to: / etc / hosts > / etc / resolv conf

Edit the configuration file / etc / nsswitch Conf modify priority

vim /etc/nsswitch.conf
59 hosts:      files dns myhostname 			#/etc/hosts priority
59 hosts:      dns files myhostname 			#/etc/resolv.conf priority

Build remote software warehouse

Install httpd

dnf install -y httpd  							#Download remote call

Turn on the httpd service and turn off the firewall

systemctl enable --now httpd
systemctl disable --now firewalld

Mount the image file to the network path:

mkdir /var/www/html/song
umount /songdir
mount /iso/rhel-8.2-x82_64-dvd.iso /var/www/html/song

Edit system files, set boot auto mount

vim /etc/rc.d/rc.local
#Add mount command
mount /iso/rhel-8.2-x82_64-dvd.iso /var/www/html/song

Configure software warehouse

vim /etc/yum.repos.d/song.repo


DHCP service configuration

Install DHCP

dnf install dhcp-server -y

Configure DHCP

cp /usr/share/doc/dhcp-server/dhcpd.conf.example /etc/dhcp/dhcpd.conf
vim /etc/dhcp/dhcpd.conf

Restart dhcpd service after configuration:

systemctl restart dhcpd

When another device obtains network information through this dhcp service, this opportunity is at / var / lib / dhcpd / dhcpd The leaves file records the information and device information obtained by other devices through local dhcp.

Construction of bridge

Edit network card configuration:

vim ifcfg-ens4

Tag bridge configuration:

vim ifcfg-br0 

Restart the network for the configuration to take effect

nmcli connection reload
nmcli connection up br0
nmcli connection up ens4

Check whether the bridge is successful

After the bridge is built, the virtual machine has no network solution

After the bridge is built, execute the following command to complete the address camouflage:

firewall-cmd --add-masquerade

After the camouflage, the virtual machine can use the network normally

Topics: Linux