SSH 2

•   generate keys by command ssh-keygen -t rsa

    And then follow the default configuration


it will generates 2 files in ~/.ssh (id_rsa and id_rsa.pub)
id_rsa : it's a private key ,should be protected.
id_rsa.pub : it's a public key .

• installing public key

you can use command ssh-copy-id  to copy public key to another computer , or you can also use scp to copy public key.

• server trust client

if server trust client to access to SSH server without password (password-less log-in)  .

1-server copy client's public key to ~/.ssh/ (ssh-copy-id or scp).
2-change public key name into authorized_keys.
3- change it's permission into 600 (chmod 600 authorized_keys).

• x11 session forwarding

To allow to run some X window programs such as (Firefox) on a remote computer.



edit sshd_config : nano /etc/ssh/sshd_config 
and check these option :

Then connect to remote computer by command:

• don't allow root log-in 

• ByTCP Wrapper

for example
to deny host 192.168.0.132 to connect to SSH server