LINUX 6--installation SSH remote access control

LINUX 6--installation SSH remote access control

-

-----------------------------------Overview-----------------------------------

SSH (secure Shell) is a secure channel protocol, which is mainly used for remote login, remote replication and other functions of character interface. The SSH protocol encrypts the data transmitted by both parties, including the user password entered when the user logs in. The SSH protocol provides better security than other applications such as the early Telnet, rsh (remote Shell, remotely execute command), RCP (remote file copy).

Asymmetric key: Public key RSA format, characterized by slow encryption, can not deduce each other.

-

Comparison of-----------------------------------features------------------------------

SSH Service : sshd allows remote login access to the service (ciphertext transfer) corresponding port number TCP 22 port
Action scenario: WAN connection or LAN connection

telnet : Remote login access (clear text transfer) corresponding port number 23
Action Scenario: only works on the local area network because it is transmitted in plaintext

---------------------------------System Environment---------------------------------

1. system Environment: CentOS6.5 "SSH server" CentOS 6.5 "Client"

2. VM virtual Machines

3. OpenSSH server is provided by packages such as Openssh,openssh-server (installed by default)
Query Software Installation command: RPM–QA | grep OpenSSH

---------------------------------Configuring the OpenSSH service-side------------------------

1. SSH services and configuration files

Modifying a configuration file

Add user Zhangsan, login with user key

Modify complete, restart service

2 at the client, create a normal user, generate public and private keys by ordinary users--key pair

Go to the server to verify the view under the public key file

-

--------------------------Client Login to the SSH server-------------------------------

LINUX 6--installation SSH remote access control