Linux Basic network Management

1. Connect a Linux host to the network and need to configure network-related settings

Generally includes:

Host Name

Ip/netmask

Routing: Default gateway

DNS Server

Primary DNS Server

Secondary DNS server

Second time DNS server

2. Static designation:

Ifcfg:ifconfig,route,netstat

Ip:object{link,addr,route},ss,tc

System-config-network-tui (Setup)

Configuration file

Centos 7: Network Configuration Tool

Nmcli,nmtui,nm-connection-editor

Dynamic allocation:

Dhcp:dynamic Host Configuration Protocol

Ifconfig

Ifconfig-a

Ifconfig eth0 (Up|down)

Ifconfig eth0 Ip/netmask [Up|down]

#立即生效

Route command:

View routes: Route-n

Add route: Route add

Route add [-net|-host] target [netmask Nm] [GW Gw][[dev] If]

Target: 10.1.249.112 Gateway: 10.1.0.1

[Email protected]]# Route add-host 10.1.249.112 GW 10.1.0.1 Dev eth0

Target: 10.1.249.0 Gateway: 10.1.0.1

[Email protected]]# Route add-net 10.1.249.0 netmask 255.255.0.0 gw 10.1.0.1 Dev eth0

[Email protected]]# Route add-net 10.1.249.0/16 GW 10.1.0.1 Dev eth0

Default Route Gateway 10.1.0.1

[Email protected]]# Route add-net 0.0.0.0 netmask 0.0.0.0 GW 10.1.0.1

[[email protected]]# route add default GW 10.1.0.1

Delete target: 10.1.249.112 Gateway: 10.1.0.1

[Email protected]]# Route del host 10.1.249.112

Delete target: 10.1.249.0 Gateway: 10.1.0.1

[Email protected]]# Route del-net 10.1.249.0 netmask 255.255.0.0

Netstat command:

Netstat-print network connections,routing tables,interface statistics,masquerade Connections,and Multicast Memberships

Show Network Connections:

netstat [--tcp|-t] [--udp|-u] [--raw|-w] [--listening|-l] [--all|-a] [--NUMERIC|-N][--EXTEND|-E] [--program|-p]

-T:TCP protocol Related

-U:UCP protocol Related

-w:raw Socket Related

-L: In listening state

-A: all States

-N: Digital display of IP and ports

-E: Extended format

-P: Show related processes and PID

Netstat common groups and:

-tan TCP protocol related, all States, with digital display IP and port

-uan UCP Protocol related, all States, to digitally display IP and ports

-TNL TCP protocol related to digital display IP and port, in listening state

-UNL UCP protocol related, digital display IP and port, in listening state

Display Interface Statistics:

Netstat-i displaying all interface data

Netstat-i=eth0 Display Eth0 Interface data

Ifconfig-s eth0 display Eth0 interface data

To set the IP command:

Ifup eth0 Open eth0 Port

Ifdown eth0 Close Eth0 Port

Set Temporary IP:

IP addr Add 10.1.249.111/16 dev eth0 label eth0:0

To delete a temporary IP:

IP addr del 10.1.249.111/16 dev eth0 label eth0:0

IP addr Flush Dev eth0 label eth0:0

SS Command:

Netstat to get socket information by traversing proc, SS uses NetLink to communicate with kernel Tcp_diag module to get socket information

Options:

-T TCP protocol related

-U UDP Protocol Related

-W Bare Socket related

-X UNIX Sock related

-L Listen Status link

-A All

-N Number format

-P related programs and PID

-E Extended Information

-M memory usage

-O Timer Information

Common combinations:

-tan TCP protocol related, all, number formats

-TANL TCP protocol related, all, number formats, listen status links

-TANLP TCP protocol related, all, number formats, listen status links related programs and PID

-uan UCP protocol related, all, numeric format

Common usage:

Ss-l Show all ports that are open locally

SS-PL Show each process specific open socket

Ss-t-A displays all TCP sockets

Ss-u-a show all UCP sockets

SS-S List Current Socket details

Ss-o State established ' (Dport =: ssh or sport =: SSH) ' Show all established SSH links

Ss-o State established ' (Dport =: http or sport =: http) ' Displays all established HTTP links

TCP Common Status:

TCP Finite state machine:

LISTEN: Monitoring

Established: Established links

Fin_wait_1: Waiting for a remote TCP link interrupt request, or confirmation of a previous link interrupt request

Fin_wait_2: Waiting for link interrupt request from remote TCP

Close-wait: Waiting for a link to be sent from a local user to interrupt the request

CLOSING: Waiting for remote TCP to confirm the link interruption

Last-ack: Wait for the original send to remote TCP link Interrupt Request Confirmation

Time-wait: Wait enough time to ensure that the remote TCP receives a link interrupt request acknowledgement

Syn-sent: Client syn_sent status

SYN-RECV: After the server has been passively opened, the client's SYN is received and the ACK state is sent.

Syn-received: Server-side status SYN_RCVD if you find that there are many SYN_RCVD states, your machine may be attacked by a SYN flood DOS (Denial of service attack)

CLOSEDSS: No connection status

3. Network configuration file

Onboot: Whether this device is activated at system boot time

Type: interface types; common Ethernet, Bridge.

UUID: Unique identification of the device

IPADDR: Specify IP Address

NETMASK: Subnet Mask

Gateway: Default Gateways

DNS1: The first DNS server points to a

DNS2: The second DNS server points to a

Userctl: Whether a normal user can control this device

Peerdns: If the value of Bootproto is "DHCP", does it allow

DHCP server-assigned DNS servers point to information that is directly overwritten in the/etc/resolv.conf file

Nic configuration file/etc/sysconfig/network-scripts

The parser performs forward and reverse queries:

/etc/hosts

Image of the local host name database and IP address

Useful for small standalone networks

Typically, before using DNS check, Getent hosts view/etc/hosts content

4. Network Card related commands:

Network interface identifies and names the associated udev configuration file

/etc/udev/rules.d/70-persistent-net.rules

To view the network card:

DMESG |grep–i ETH

Ethtool-i eth0

To uninstall the NIC driver:

Modprobe-r e1000

Rmmod e1000

Load NIC driver:

Modprobe e1000

5. Use traditional naming methods:

(1) Edit/etc/default/grub configuration file grub_cmdline_linux= "RHGB quiet net.ifnames=0" or: Modify/boot/grub2/grub.cfg

(2) generate its configuration file for Grub2 grub2-mkconfig-o/etc/grub2.cfg

(3) Rebooting the system

This article is from the "Linux Learning path" blog, so be sure to keep this source http://luyubo.blog.51cto.com/7634254/1847180

Linux Basic network Management