SSH免密码登录Linux服务器

服务器：Ubuntu 16.04 x64

本机：Ubuntu 16.04 x64

1、查看本机是否存在密钥对

username@ubuntu:~$ cd ~/.ssh
username@ubuntu:~/.ssh$ ls
id_rsa  id_rsa.pub

2、如果不存在，则首先生成密钥对

username@ubuntu:~$ ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/home/username/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/username/.ssh/id_rsa.
Your public key has been saved in /home/username/.ssh/id_rsa.pub.
The key fingerprint is:
SHA256:xxxxxxxxxxxxxxxxxxxx username@ubuntu

The key's randomart image is:
+---[RSA 2048]----+
|                 |
|                 |
|                 |
|        A        |
|    randomart    |
|      image      |
|                 |
|                 |
|                 |
+----[SHA256]-----+

3、将本机公钥上传到远程服务器

username@ubuntu:~$ scp ~/.ssh/id_rsa.pub root@romote_server_IP:/root/
The authenticity of host 'romote_server_IP (romote_server_IP)' can't be established.
ECDSA key fingerprint is SHA256:xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added 'romote_server_IP' (ECDSA) to the list of known hosts.
root@romote_server_IP's password: xxxxxxxxxx
id_rsa.pub                                    100%  390     0.4KB/s   00:00
username@ubuntu:~$

4、登录远程服务器，将本机公钥添加到远程服务器的authorized_keys中，如果服务器中用户目录下不存在.ssh文件夹和authorized_keys文件，则新建并修改权限

username@ubuntu:~$ ssh root@romote_server_IP
root@romote_server_IP's password:
Welcome to Ubuntu 16.04.x LTS (GNU/Linux x.x.x-xx-generic x86_64)

* Documentation:  https://help.ubuntu.com * Management:     https://landscape.canonical.com * Support:        https://ubuntu.com/advantage 
xx packages can be updated.
xx updates are security updates.

Last login: last_login_time from xxx.xx.xx.xxx
root@remote_server:~# ls -a
.   .bash_history  .cache    .viminfo    id_rsa.pub
..  .bashrc        .profile  .wget-hsts
root@remote_server:~# mkdir .ssh
root@remote_server:~# chmod 700 ~/.ssh
root@remote_server:~# touch ~/.ssh/authorized_keys
root@remote_server:~# chmod 600 ~/.ssh/authorized_keys
root@remote_server:~# cat ~/id_rsa.pub >> ~/.ssh/authorized_keys
root@remote_server:~#

5、本机配置远程服务器别名代替IP地址

username@ubuntu:~$ vim ~/.ssh/config
Host remote_server_alias
HostName xxx.xxx.xx.xx
Port 22
User remote_server_username
PreferredAuthentications publickey
IdentityFile ~/.ssh/id_rsa
~
~
:wq
username@ubuntu:~$ ssh remote_server_alias
Welcome to Ubuntu 16.04.x LTS (GNU/Linux x.x.x-xx-generic x86_64)

* Documentation:  https://help.ubuntu.com * Management:     https://landscape.canonical.com * Support:        https://ubuntu.com/advantage 
xx packages can be updated.
xx updates are security updates.

Last login: last_login_time from xxx.xx.xx.xxx
root@remote_server:~#