Linux installation ssh and SSH usage with password-free login

First, configure Yum

Second, what is SSH

• The administrator can manage the multiple hosts scattered across the network by remote login.
• Administrators can do the following for remote hosts:
  • Remote Login
  • remote command execution
  • Remote File transfer
• The sad thing is: these operations are unsafe!
• Use plaintext passwords and send them in clear text
  • Information may be intercepted and passwords may be retrieved
  • Unauthorized personnel using the intercepted password to log on to the system, causing damage to the system

SSH 's Goal

• Provide secure network services on unsecured networks.

Third, installation command

　　

Yum install-y openssh-server openssh-clients

To start SSH:

Service sshd start or/etc/init.d/sshd start

To configure boot boot:

Chkconfig--level 2345 sshd on

Four, ssh password-free login

Ssh-keygen's command manual, through the "Man Ssh-keygen" command:

1. Generate Secret Keys

SSH-KEYGEN-T RSA

　　

A ". SSH" folder will be generated at the user's root directory after the build

　　

Entering ". SSH" will generate the following files

　　

Authorized_keys: The public key that stores the remote password-free login, which records the public key of multiple machines mainly through this file.

ID_RSA: Generated private key file

Id_rsa.pub: Generated Public key file

Know_hosts: List of known host public keys

If you want the SSH public key to take effect, at least two of the following conditions will be met:

1). The SSH directory must have permissions of 700

2). The. ssh/authorized_keys file permission must be 600

2. Password-Free login method

2.1 By way of Ssh-copy-id

Command: Ssh-copy-id-i ~/.ssh/id_rsa.put [ip/hosts]

　　　　

　　　　

2.2 Writing content to each other's files via SCP

Command: scp-p ~/.ssh/id_rsa.pub [Email Protected]<remote_ip>:/root/.ssh/authorized_keys

　　　　

V. Usage of SSH

1.SSH Login to another Linux

SSH [ip/hosts]

　　

Sign Out:

Exit

2. Copying files

Grammar:

SCP the file name (relative or absolute path) to be copied to the ip:/path of the machine to be copied to

3. Copying folders

Grammar:

Scp–r folder [email protected]/hosts:/path

　　

　　

Linux installation ssh and SSH usage with password-free login