配置linux服务器之间ssh不用密码访问

如果想在 A 这太机器上可以不需要密码就 ssh 到 B 、 C 两台机器上,可以采用如下的方法:

( 1 ) 在 A 机器上: ssh-keygen -t rsa

Generating public/private rsa key pair.
Enter file in which to save the key (/nutch/home/.ssh/id_rsa): 不输入任何东西,直接回车
Enter passphrase (empty for no passphrase): 不输入任何东西,直接回车
Enter same passphrase again: 不输入任何东西,直接回车
Your identification has been saved in /nutch/home/.ssh/id_rsa.
Your public key has been saved in /nutch/home/.ssh/id_rsa.pub.
The key fingerprint is:
40:b8:e9:8f:0a:f6:ce:e0:73:a8:6a:7e:52:b4:45:ca nutch@linux1

这个命令将为 A 上的用户生成其密钥对,询问其保存路径时直接回车采用默认路径,当提示要为生成的密钥输入passphrase 的时候,直接回车,也就是将 其设定为空密码。生成的密钥对 id_rsa , id_rsa.pub ,默认存储在/home/username/.ssh 目录下。

(2) 在 A 机器上:将 id_rsa.pub 的内容复制到 A 、 B 、 C 三台机器 /home/username/.ssh/authorized_keys 文件中,如果机器上已经有 authorized_keys 这个文件了,就在文件末尾加上 id_rsa.pub 中的内容,如果没有authorized_keys 这个文件,直接 cp 或者 scp 就好了,下面的操作假设各个机器上都没有 authorized_keys 文件。(如果 B 、 C 机器上没有 ~/.ssh 目录可以手动自己创建 , 权限要设置成可以写,因为要 copyauthorized_keys)

对于 A : cp id_rsa.pub authorized_keys

对于 B 和 C : scp authorized_keys username@B:~/.ssh/ 此处的 username 是要访问的 B 机器上的用户名。

(3) chmod 644 authorized_keys
这一步非常关键,必须保证 authorized_keys 只对其所有者有读写权限,其他人不允许有写的权限,否则 SSH 是不会工作的

(4) 可以直接 ssh username@ 机器名了,同一台机器的不同用户直接也可以以这种方式来访问

 

如果经过上面的步骤还是提示需要密码,注意一下权限问题,主要有三个权限

(1) /home/username这目录的权限应该是700

(2) /home/username/.ssh 这个目录的权限也应该是700

(3) /home/username/.ssh/ authorized_keys这个文件的权限是644

如果还是不正确,那么tail /var/log/secure一下这个日志文件,就能发现问题。

 

 

————-其他的ssh问题——————————————–

刚装了ubuntu,ssh localhost如果提示ssh: connect to host lcoalhost port 22: Connection refused

那么有可能是openssh-server没有安装,可以通过命令ps -e|grep ssh 来查看ssh-server是否开启,如果ps -e|grep ssh只显示ssh-agent,并且/etc/init.d/目录下没有ssh,那说明系统并没有安装ssh-server,因此可以通过如下命令来安装ssh-server:

sudo apt-get install openssh-server

并可以通过/etc/init.d/ssh start命令开启(一般安装openssh-server后会自动开动的)

可以通过命令netstat -tlp来查看sshd是否运行
tcp6    0    0 *:ssh                *:*                   LISTEN     –
看到上面这一行输出说明ssh-server已经在运行了。

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