ssh config

what is ssh? 

SSH is a protocol to log-in remote server. it's the most common way to access remote server in linux system and linux commands is useful in linux system, in this articles, how to ssh config?

Syntax:

ssh remote_username@remote_host 

Note:

• remote_username: user of server you wish remote access.
• remote_host: ip address or domain name of remote access the server.

how does ssh work?

SSH works by a client program which it's connecting to an ssh server. Client-side as command above and server-side  service sshd server already running.

Basic of ssh config

SSH config the store in /etc/ssh/sshd_config file.

vi /etc/ssh/sshd_config

Disable or enable root log-in

PermitRootLogin yes

if you allow root access thought ssh use as command above, contrary.

Change port ssh

Default ssh port 22, you can change port non-standard.

Port 8888

Note: you check firewall in centos actually open . if firewall not open port 8888 you open port 8888 as command line bellow:

 firewall-cmd --zone=public --query-port=8888/tcp

Open the port 8888 in firewall using command line as bellow:

firewall-cmd --zone=public --add-port=8888/tcp --permanent

Restart ssh config:

systemctl reload sshd.service

you can via linux firewall to more detail:

Other configuration 

# Authentication:
LoginGraceTime 2m
StrictModes yes
MaxAuthTries 6
MaxSessions 10 

How to login ssh use keys

Log-in ssh use keys a better idea for secure to access remote server. Key-base authentication works by creating a pair of keys:

• Private key: the located on the client
• Public key: the located on server you wish access and for anyone.

How to create SSH keys

Enter the following into the command line and press enter by default:

ssh-keygen -t rsa

The command above create 2 file in hidden ~/.ssh folder :  ~/.ssh/id_rsa.pub and ~/.ssh/id_rsa.

Change to ssh directory use cd command as bellow:

cd ~/.ssh 

ls -l

How to transfer public key to the server

ssh-copy-id remote_host

I hope will this help you!
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