ssh-keygen -t rsa

[user@client]$ 

The authenticity of host 'server.domain.ru (36.84.75.18)' can't be established.

RSA key fingerprint is 59:dc:5b:ee:4b:92:35:82:77:a4:99:80:3e:8c:a0:23.

Are you sure you want to continue connecting (yes/no)? - Отвечаем yes

Warning: Permanently added 'server.domain.ru,

root@server.domain.ru's password: 

BackupPC_id_rsa.pub                                                                        100%  456     0.8KB/s   00:00

[root@server]# ssh-keygen -t rsa

Generating public/private rsa key pair.

Enter file in which to save the key (/root/.ssh/id_rsa):  - Жмем Enter

Enter passphrase (empty for no passphrase):  

- Жмем Enter

Enter same passphrase again:  

- Жмем Enter

Your identification has been saved in /root/.ssh/id_rsa.

Your public key has been saved in /root/.ssh/id_rsa.pub.

The key fingerprint is:

84:f6:05:8d:4e:ad:ff:d1:9e:04:51:36:da:97:ac:5b root@server.domain.ru

[root@server]# cat ~/.ssh/BackupPC_id_rsa.pub >> ~/.ssh/authorized_keys2

 В начале файла 

from="client.domain.ru"

Должно выглядеть так:

from="

The authenticity of host 'client.domain.ru (436.44.75.196)' can't be established.

RSA key fingerprint is 59:dc:5b:ee:5b:9c:32:82:f7:a4:9e:80:6e:8c:a0:23.

Are you sure you want to continue connecting (yes/no)? - Отвечаем yes

Warning: Permanently added 'client.domain.ru,

root@client.domain.ru's password: 

id_rsa.pub                                                                                                                                   100%  406     0.4KB/s   00:00    

[user@client]$