SSH免密登陆

现在很多部署在Linux集群的软件系统都会涉及到ssh免密登陆，例如Oracle的Rac、Hadoop等，下面将简单介绍一下SSH的免密登陆

前期准备：VirtualBox软件，Ubuntu虚拟机2台（node,node1）

node:192.168.57.101

node1:192.168.57.103

现在想实现两个节点之间彼此的免密ssh登陆

生成rsa密钥

root@node:~# ssh-keygen -t rsa -P ‘’

参数P表示存在密码，可以在后面加自定义密码，我这里为了方便用的是-P ‘’空字符串表示密码为空，当然也可以不加P参数但是需要多回车两次，回车后就会在/root目录下生成ssh目录，如果你用的其他用户登陆如XX则会在/home/XX下生成.ssh目录，目录里有id_rsa和id_rsa.pub文件，这两个文件就是用来实现免密登陆的。

root@node:~# ssh-keygen -t rsa -P ''Generating public/private rsa key pair.Enter file in which to save the key (/root/.ssh/id_rsa): Created directory '/root/.ssh'.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:SHA256:jxfmhN3Oofu0DzIbGv3mGBw6VgcX5YBnkp1XemeiqfY root@nodeThe key's randomart image is:+---[RSA 2048]----+| +oo...|| + =+.. || .+..+ +|| o + o +.|| S B * || @ O . || * # = || . * %.o || . ++E.. |+----[SHA256]-----+

使用scp命令将生成的id_rsa.pub文件上传到node1指定目录

root@node:~# scp /root/.ssh/id_rsa.pub root@192.168.57.103:/root

由于目前没有实现免密登陆所以需要输入密码

The authenticity of host '192.168.57.103 (192.168.57.103)' can't be established.ECDSA key fingerprint is SHA256:+rYv2fdh3HngKOh1p/X1LTRHn66BW9jA8EPJO6vwiN8.Are you sure you want to continue connecting (yes/no)? yesWarning: Permanently added '192.168.57.103' (ECDSA) to the list of known hosts.root@192.168.57.103's password: id_rsa.pub 100% 391 0.4KB/s 00:00

下一步将在node1把从node复制过来的id_rsa.pub文件添加到.ssh/authorzied_keys文件中

在node1端

root@node1:~# cat id_rsa.pub >> .ssh/authorized_keys

然后再给authorized_keys添加600的权限

root@node1:~# chmod 600 .ssh/authorized_keys

至此完成了ssh免密登陆的配置，测试一下成功，同理从node1免密登陆也是一样的

root@node:~# ssh 192.168.57.103Welcome to Ubuntu 16.04.2 LTS (GNU/Linux 4.4.0-62-generic x86_64) * Documentation:  * Management:  * Support:  个可升级软件包。8 个安全更新。Last login: Thu Jul 6 15:32:09 2017 from 192.168.57.1