Linux network configuration and SSH and Shell basics

Linux network configuration and SSH and Shell basics

First, the Linux network configuration

The ifconfig command is used to configure and display network parameters for network interfaces in the Linux kernel. The NIC information configured with the Ifconfig command does not exist after the machine restarts after the network card restarts. In order to keep the above configuration information in the computer forever, it is necessary to modify the network card configuration file.

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Second, the role of the Hosts file and modify host name

Hosts:the static table lookup for host name (host-Name query-still tables)

Linux /etc/hosts is a file that configures the IP address and its corresponding hostname, where you can log the IP of the machine or other host and its corresponding host name. Different versions of Linux, this configuration file may also be different. For example CentOS7 the corresponding file is/etc/hostname.

In CentOS, there are three definitions of host names: static, transient (transient), and flexible (pretty). The "Static" hostname, also known as the kernel hostname, is the host name that the system automatically initializes from/etc/hostname at startup. A "transient" hostname is a host name that is temporarily assigned when the system is running, for example, through DHCP or MDNs server assignment. The static hostname and transient host name comply with the same character restriction rules as the Internet domain name.

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Third, the configuration of SSH

SSH is a secure transport protocol based on the transport layer and application layer. SSH is now more reliable, and is designed for remote logins and other network-provided security protocols.

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Note: SSH default port 22 can be normally logged in without SELinux, but if you change the default port number to 8888, you must turn off SELinux and clean up the iptables rules, otherwise the connection will be error!

Four, Bash command collation

Command execution Priority:

Alias "command" function built-in command "hash path cache" $PATH "command not Found

The following is a reprint of the Bash Command collation Daquan:

https://my.oschina.net/sanpeterguo/blog/207335

Command Tools

Alias Create/Display aliases

Type position command: Displays the path name or alias of the command

Unalias Deleting aliases

Whence location command: Displays the path name or alias of the command

Which location command: Displays the path name or alias of the command

Compare files

CMP Comparison of two files

Comm Comparison of two ordered files, showing the difference

Diff compares two files, showing the difference

Sdiff compare two files, show difference

Directory

CD Change Working directory

chmod changing file permissions for a file or directory

Dirs Show/clear content in the directory stack

Du displays the amount of disk space used by the file

Types of file parsing files

LS displays various types of information for the file

mkdir Creating a Directory

MV Move or rename files or directories

POPD changing the working directory to eject the name from the directory stack

PUSHD changing the working directory, pressing the name into the directory stack

PWD Displays the path name of the working directory

RM Delete a file or directory

RmDir Delete Empty Directory

Tree displays a chart of the directory Trees

Show data

Cat combo file, copy standard input to standard output

Echo writes parameters to standard output

Head selects rows from the beginning of the data

Hexdump displaying binary (non-text) files

Less pager: Display data one screen at a time

More Distribution program: Display data one screen at a time

OD displays binary (non-text) files

Print writes parameters to standard output

Tail select rows at the end of the data

Document Information

Apropos display command names based on keyboard search

Info displays files from the Info reference system

Man Displays the UNIX online reference manual page

Whatis displays a single row of summary information for the specified command

Xman GUI-based page showing the online reference manual

Edit

Sed non-interactive text editing

VI VI text Editor

View launches VI text Editor in read-only mode

Vim Vim Text Editor

File

chmod changing file permissions for a file or directory

CP copy file; copy directory

Du displays the amount of disk space used by the file

Find searches the directory tree for files, processing the results

LN creates a new link to the file

Locate searching for files

LS displays various types of information for the file

Mkfifo Creating Named Pipes

MV Move or rename files or directories

RM Delete a file or directory

Shred Safely Delete files

Stat Display I-node information

Access/modification time of the touch update file;

Umask Setting the file mode mask during file creation

Whence location command: Displays the path name or alias of the command

Whereis viewing files associated with a command

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Linux network configuration and SSH and Shell basics