Linux network settings

Linux network settings

1. View network interface information

1. View all active network interface information

ifconfig

2. View the information of the specified network interface

ifconfig 网络接口

Painted in red mtu1500, where mtu refers to the maximum transmission unit, its number of bytes is 1500 bytes,

Inappropriate local MTU value

1. When the local MTU value> the network MTU value————> unpacking is required, which will result in a decrease in efficiency

2. When the local MTU value <network MTU value————> does not exert the maximum transmission capacity

3. When the local MTU value = the network MTU value ---> this is the ideal local MTU value

Two, view the host name

1. View or temporarily set the current hostname

hostname [主机名]————这是临时的，重启或者下次开机之后就会失效

2. Permanently set the host name

hostnamectl set-hostname [主机名]

or

vim /etc/hostname————必须要设置在第一行才有效，并且设置完成后需重启系统才生效

Three, view routing table entries

route [-n]

Four, check the network connection netstat

1. View the system's network connection status, routing table, interface statistics and other information

netstat [选项]

Common options:

-a: Display all active network connection information in the host (including monitoring and non-monitoring service ports)
-n: Display the relevant host address, port and other information in the form of numbers.
-t: View information related to the TCP protocol.
-u: Display information related to UDP protocol.
-p: Display the process number and process name information associated with the network connection (this option requires root privileges)
-r: Display the routing table information.
-l: Display the network connection and port information in the monitoring state.

Five, get socket statistics information ss

View the network connection of the system and obtain socket statistics

ss [选项]

Common options:

-t、-u、-n、-l、-p、-a、-r

Six, test network connection ping

Test network connectivity

ping [options] target host

Seven, trace data packet traceroute

Test the network nodes that pass from the current host to the destination host

traceroute 目标主机地址

8. Domain name resolution nslookup

Test DNS domain name resolution

nslookup 目标主机地址 [DNS服务器地址]

Nine, the method of setting network parameters

1. Temporary configuration-use commands to adjust network parameters

• Simple, fast, can directly modify the network parameters in operation
• Generally only suitable for use in the process of debugging the network
• After the system restarts, the changes made will be invalid

2. Fixed settings-modify network parameters through configuration files

• Modify configuration files of various network parameters
• Suitable for use when setting fixed parameters for the server
• Need to reload the network service or restart to take effect

10. Set the network interface parameters ifconfig

1. Set the IP address and subnet mask of the network interface

ifconfig 网络接口 ip地址 [netmask 子网掩码]

ifconfig 网络接口 ip地址[/子网掩码长度]

2. Disable or reactivate the network card

ifconfig 网络接口 up

ifconfig 网络接口 down

3. Set up virtual network interface

inconfig 网络接口:序号 ip地址

11. Set the route record route

1. The route added to the specified network is recorded

toute add -net 网段地址 gw ip地址

2. Delete the routing record to the specified network segment

route del -net 网段地址

3. Add the default gateway record to the routing table

route add default gw ip地址

4. Delete the default gateway record in the routing table

route del default gw ip address

5. Permanently add a route-need to restart the network card service to take effect

method one,

vim /etc/sysconfig/static-routes

any net any gw 192.168.80.2

any net 192.168.3.0/24 gw 192.168.80.2

any host 192.168.100.100 gw 192.168.80.2

systemctl restart network

Method Two,

vim /etc/sysconfig/network-scripts/ifcfg-ens33 

default via 192.168.80.2 dev ens33——————默认路由的另一种格式 0.0.0.0/0   192.168.14.254 dev ens33

10.211.6.0/24 via 192.168.80.2 dev ens33

192.168.100.100 via 192.168.14.254 dev ens33

systemctl restart network

12. Network interface configuration file

1. The location of the configuration file

vim   /etc/sysconfig/network-scripts/ifcfg-ens33 

TYPE=Ethernet—————— Set the network card type
BOOTPROTO=static———— The way to obtain the IP address, "static" obtains the IP address statically, and "dhcp" obtains the IP address dynamically
IPADDR=192.168.241.3————IP Address
NETMASK=255.255.255.0————Subnet mask
GATEWAY=192.168.241.2————Gateway address
ONBOOT=yes————Automatically activate
DEVICE=ens33——————Network card name

Thirteen, enable and disable network interface configuration

1. Several ways to restart the network card

systemctl restart network

service network restart

/etc/init.d/network restart

2. Disable and enable designated network card

ifdown ens33————禁用ens33网络接口

ifup ens33————开启ens33网络接口

14. Domain name resolution configuration file

vim  /etc/resolv.conf  

Save the IP address of the DNS server that the machine needs to use

15. Local host mapping file

1. /etc/hosts file

• Save the mapping record of host name and ip address

2. Comparison of hosts file and DNS server

• By default, the system first searches for the analysis record from the hosts file
• The hosts file is only valid for the current host
• The hosts file can reduce the DNS query process, thereby speeding up access