3. Remote connection and SSH

First, configure the virtual machine network , And then through ip addr The command can get IP Address .
ssh agreement ：
SSH Express Secure SHell Abbreviation . Means safe Shell.shell It's English “ shell ” It means . adopt SSH agreement , The information transmitted between the two machines will be encrypted , This ensures the security of transmission information .

Symmetric and asymmetric encryption SSH agreement

Symmetric encryption ： Symmetric encryption uses a key to encrypt and decrypt . The drawback is that the key must be passed carefully
Asymmetric encryption ： Encrypt with one key and decrypt with another key . One is the public key , Is used to encrypt ; One is the private key used for decryption . The most famous belongs to RSA Algorithm .
SSH Combine asymmetric encryption and symmetric encryption to build a secure access pipeline ：

• First use asymmetric encryption , Secure transmission of symmetric encrypted keys
• Since then, symmetric encryption has been used as a means of encryption and decryption
  Because asymmetric encryption consumes too much resources , Therefore, asymmetric encryption is first used between the two computers Exchange symmetric encryption keys , Then we can use symmetric encryption to communicate faster . Because the key of symmetric encryption is transmitted using asymmetric encryption , It has never appeared in clear text on the network , Therefore, the security of the key is guaranteed .

SSH actual combat

OpenSSH
OpenSHH yes SSH Free and open source implementation of the protocol , It is divided into server and client . If you need to be a server , Then you need to install openssh-server, If it is a client, it is openssh-client.
Server installation SSH service
install SSH service
yum install openssh-server
start-up SSH
systemctl start( or restart) sshd
Set the power on to run SSH
systemctl enable sshd
SSH client :
Linux System :openssh-clint , Connection command ssh Server user name @ Server address for example [email protected]
Window System :xshell etc.