1、ssh-keygen -t rsa -P ‘‘ -f ~/.ssh/id_rsa　　// 在自己主机生成私钥和公钥

2、scp id_rsa.pub [email protected]:/home/centos/.ssh/authorized_keys 　　// 分发公钥

// 安装　scp

yum -y install openssh-clients

第二种：

ssh免密登陆

ssh-keygen // 生成密匙

ssh-copy-id 192.168.80.11 // 拷贝公钥到远程服务器上

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杂记：

安装 时间同步软件

yum install -y ntpdate

2、查看本机是否安装了ntpdate服务

3、同步时间

ntpdate time.nist.gov // 同步时间

如果同步不了

ntpdate time.nuri.net // 校验时间 系统时间

把系统时间写入硬件时间

hwclock -w // 写入时间

SSH免密登陆

1.每台都要设置

mkdir ~/.ssh
chmod 700 ~/.ssh
vi /etc/ssh/sshd_config

内容：

RSAAuthentication yes # 启用 RSA 认证
PubkeyAuthentication yes # 启用公钥私钥配对认证方式
AuthorizedKeysFile .ssh/authorized_keys # 公钥文件路径（和下面生成的文件同）

2.master上生产密钥

ssh-keygen -t rsa -P ''
cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
chmod 700 ~/.ssh
chmod 600 ~/.ssh/authorized_keys

service sshd restart
scp ~/.ssh/id_rsa.pub root@slave1.hadoop:~/.ssh
scp ~/.ssh/id_rsa.pub root@slave2.hadoop:~/.ssh

3.每台slave上执行

cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
chmod 600 ~/.ssh/authorized_keys
rm -r ~/.ssh/id_rsa.pub

4.master上测试

ssh slave1.hadoop
exit
ssh slave2.hadoop
exit

 1 [root@localhost ~]# ssh-copy-id -i root@worker1
 2 /usr/bin/ssh-copy-id: INFO: Source of key(s) to be installed: "/root/.ssh/id_rsa.pub"
 3 /usr/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed
 4 /usr/bin/ssh-copy-id: INFO: 1 key(s) remain to be installed -- if you are prompted now it is to install the new keys
 5 root@worker1''s password:
 6 
 7 Number of key(s) added: 1
 8 
 9 Now try logging into the machine, with:   "ssh ''root@worker1''"
10 and check to make sure that only the key(s) you wanted were added.

1 [root@test .ssh]# scp -p ~/.ssh/id_rsa.pub root@192.168.91.135:/root/.ssh/authorized_keys
2 root@192.168.91.135''s password: 
3 id_rsa.pub 100% 408 0.4KB/s 00:00 
4 [root@test .ssh]# 
5 [root@test .ssh]# 
6 [root@test .ssh]# 
7 [root@test .ssh]# ssh root@192.168.91.135
8 Last login: Mon Oct 10 01:27:02 2016 from 192.168.91.133
9 [root@localhost ~]#

$ scp ~/.ssh/id_rsa.pub root@<remote_ip>:pub_key //将文件拷贝至远程服务器
$ cat ~/pub_key >>~/.ssh/authorized_keys //将内容追加到authorized_keys文件中， 不过要登录远程服务器来执行这条命令

[Avoid close]
192.168.91.132
192.168.91.133
192.168.91.134
//执行命令进行免密操作
ansible <groupname> -m authorized_key -a "user=root key=''{{ lookup(''file'',''/root/.ssh/id_rsa.pub'') }}''" -k

示例：
[root@test sshpass-1.05]# ansible test -m authorized_key -a "user=root key=''{{ lookup(''file'',''/root/.ssh/id_rsa.pub'') }}''" -k
　　SSH password: ----->输入密码
　　192.168.91.135 | success >> {
　　"changed": true, 
　　"key": "ssh-rsa 　　 AAAAB3NzaC1yc2EAAAABIwAAAQEArZI4kxlYuw7j1nt5ueIpTPWfGBJoZ8Mb02OJHR8yGW7A3izwT3/uhkK7RkaGavBbAlprp5bxp3i0TyNxa/apBQG5NiqhYO8YCuiGYGsQAGwZCBlNLF3gq1/18B6FV5moE/8yTbFA4dBQahdtVP PejLlSAbb5ZoGK8AtLlcRq49IENoXB99tnFVn3gMM0aX24ido1ZF9RfRWzfYF7bVsLsrIiMPmVNe5KaGL9kZ0svzoZ708yjWQQCEYWp0m+sODbtGPC34HMGAHjFlsC/SJffLuT/ug/hhCJUYeExHIkJF8OyvfC6DeF7ArI6zdKER7D8M0SM　　WQmpKUltj2nltuv3w== root@localhost.localdomain", 
　　"key_options": null, 
　　"keyfile": "/root/.ssh/authorized_keys", 
　　"manage_dir": true, 
　　"path": null, 
　　"state": "present", 
　　"unique": false, 
　　"user": "root"
　　}

root# chmod 700 .ssh 文件夹权限
root# chmod 600 .ssh/authorized_keys  文件权限

root# service sshd stop  # 停止服务
root# /usr/sbin/sshd  #用这个方式启动试试