SSH证书登录
使用任意工具生成密钥对，可用工具如puttygen或你所使用的SSH登录工具， 也可以是linxu系统中的ssh-keygen
Puttygen示例:
puttygen 生成时加密方式选择： SSH-2 RSA
保存公钥/私钥，在服务器上执行以下命令：
mkdir ~/.ssh
touch ~/.ssh/authorized_keys
#权限设置(RHEL/CENTOS系统必需)
chmod 700 ~/.ssh
chmod 600 ~/.ssh/authorized_keys
将公钥中的内容复制到authorized_keys文件
将私钥导入你自已的登录工具，如：putty 即可免密码登录
ssh-keygen示例:
$ ssh-keygen -t rsa -b 2048
一直回车完成生成id_rsa与id_rsa.pub
mkdir ~/.ssh
touch ~/.ssh/authorized_keys
#权限设置(RHEL/CENTOS系统必需)
chmod 700 ~/.ssh
chmod 600 ~/.ssh/authorized_keys
将id_rsa.pub中的内容复制到authorized_keys文件
将id_rsa下载/导入你自已的登录工具，若使用putty需先使用puttygen导入密钥后存储为ppk格式
LINUX相互免密码互通：
使用ssky-keygen和ssh-copy-id设置而无需输入密码就能登录远程Linux主机。
1、ssh-keygen 创建公钥和密钥。
2、ssh-copy-id 把本地主机的公钥复制到远程主机的authorized_keys文件上。
注：ssh-copy-id 也会给远程主机的用户主目录（home）和~/.ssh, 和~/.ssh/authorized_keys设置合适的权限 。
本地拷贝远程：
步骤1: 用 ssh-key-gen 在本地主机上创建公钥和密钥
ligh@local-host$ ssh-keygen -t rsa
Enter file in which to save the key (/home/jsmith/.ssh/id_rsa):[Enter key]
Enter passphrase (empty for no passphrase): [Press enter key]
Enter same passphrase again: [Pess enter key]
Your identification has been saved in /home/jsmith/.ssh/id_rsa.
Your public key has been saved in /home/jsmith/.ssh/id_rsa.pub.
The key fingerprint is: 33:b3:fe:af:95:95:18:11:31:d5:de:96:2f:f2:35:f9
ligh@local-host
步骤2: 用 ssh-copy-id 把公钥复制到远程主机上
ligh@local-host$ ssh-copy-id -i ~/.ssh/id_rsa.pub root@192.168.0.3
ligh@remote-host‘s password:
Now try logging into the machine, with ―ssh ?remote-host‘‖, and check in:
.ssh/authorized_keys to make sure we haven‘t added extra keys that you weren‘t expecting.
[注: ssh-copy-id 把密钥追加到远程主机的 .ssh/authorized_key 上.]
步骤3: 示例，直接登录远程主机
ligh@local-host$ ssh 192.168.0.3使用下例中ssky-keygen和ssh-copy-id，仅需通过3个步骤的简单设置而无需输入密码就能登录远程Linux主机。
ssh-keygen 创建公钥和密钥。
ssh-copy-id 把本地主机的公钥复制到远程主机的authorized_keys文件上。
ssh-copy-id 也会给远程主机的用户主目录（home）和~/.ssh, 和~/.ssh/authorized_keys设置合适的权限 。
步骤1: 用 ssh-key-gen 在本地主机上创建公钥和密钥
ligh@local-host$ ssh-keygen -t rsa
Enter file in which to save the key (/home/jsmith/.ssh/id_rsa):[Enter key]
Enter passphrase (empty for no passphrase): [Press enter key]
Enter same passphrase again: [Pess enter key]
Your identification has been saved in /home/jsmith/.ssh/id_rsa.
Your public key has been saved in /home/jsmith/.ssh/id_rsa.pub.
The key fingerprint is: 33:b3:fe:af:95:95:18:11:31:d5:de:96:2f:f2:35:f9
ligh@local-host
步骤2: 用 ssh-copy-id 把公钥复制到远程主机上
ligh@local-host$ ssh-copy-id -i ~/.ssh/id_rsa.pub root@192.168.0.3
ligh@remote-host‘s password:
Now try logging into the machine, with ―ssh ?remote-host‘‖, and check in:
.ssh/authorized_keys to make sure we haven‘t added extra keys that you weren‘t expecting.
[注: ssh-copy-id 把密钥追加到远程主机的 .ssh/authorized_key 上.]
步骤3: 直接登录远程主机
ligh@local-host$ ssh 192.168.0.3
Last login: Sun Nov 16 17:22:33 2008 from 192.168.1.2
[注: SSH 不会询问密码.]
ligh@remote-host$
[注: 你现在已经登录到了远程主机上]
Last login: Sun Nov 16 17:22:33 2008 from 192.168.1.2
[注: SSH 不会询问密码.]
ligh@remote-host$
[注: 你现在已经登录到了远程主机上]