Deployment and optimization services security Openssh

A, Openssh function

• OpenSSH: is free and open source software SSH (Secure SHell) protocol.
• Software installation Name: Openssh-server
• Configuration file: / etc / ssh / sshd_conf
• The default port: 22
• Client command: ssh

Two, ssh command

ssh 	remoteUSER@remoteIP
		-l 		指定登录用户
		-i 		指定密钥
		-x 		开启图形
		-p 		指定端口
		-f 		后台运行
		-o 		指定连接参数
		-t 		指定连接跳板

(1) ssh login

(2) -l login user specified

(3) -x opening pattern


(4) -p specified port

(5) -f background

(6) -o connection parameters specified

(7) -t specified connection springboard

Three, key certification services Openssh

1, Openssh authentication method

(1) password authentication
• at least six characters
• contain numbers, letters, underscores the special symbols
• leakiness
• can be brute
• Passwords are easily lost
(2) Key Authentication
• New authentication methods, divided into public and private keys
• Upload the public key server
• private key pair authentication is not misappropriated
• attackers generally can not log in through key server

2、Openssh KEY

Openssh KEY: support rsa and dsa encryption
encryption methods:

生成密钥 	ssh-keygen
上传密钥 	ssh-copy-id 	–i 	keyfile 	remoteUSER@remoteIP

(1) generating a secret key-keygen SSH


(2) uploading the key ssh-copy-id -i keyfile remoteUSER @ remoteIP

3, the document on Openssh

file	Features
~/.ssh/authorized_keys	To save the user's public key file
~/.ssh/known_hosts	Unique hash code to identify the server
~/.ssh/id_dsa	User's private key file
~/.ssh/id_rsa.pub	User's public key file

Fourth, the security services to optimize Openssh

Common service sshd configuration parameters:
the configuration file:
• / etc / SSH / sshd_config
configuration parameters:

parameter	meaning
Port 22	Listening port
Protocol 2	Specify a protocol version
ListenAddress	Binding IP
HostKey	Key Path set HostKey
PermitRootLogin	Whether to set a super user can log
PubkeyAuthentication	Public key authentication switch
PasswordAuthentication	Password authentication switch
AllowUsers	User white list
DenyUsers	Users blacklist