0 总结
Get to the points first. The article comes from LawsonAbs!
  • updata on 20200505：修改相关格式
1.环境简介
  • windows 10【物理机】 + centos 6.5【虚拟机】
  • hadoop 2.6.4
2.为什么需要ssh? 3.ssh协议原理

[待完善]

4.ssh免密搭建
  • step 01.查看当前目录下的.ssh文件
[root@littlelawson ~]# ls -a
...
.bash_profile    .gconfd            .m2                    region_split_info_two.txt  
.bashrc          .gnome2            Main$$anonfun$1.class  region_split_info.txt      
bigdata          .gnome2_private    Main.class             .scala_history             
.cache           .gvfs              metastore_db           StatsWithMissing.scala     
.config          hadoop_temp        .mozilla               .ssh
create           HelloLinux.txt     MyKafka.csv            temp.csv
.cshrc           .idea-build        .mysql_history         TestConstructor.class
.dbus            .IdeaIC2018.1      myvalue                TestConstructor.scala
  • step 02.使用rsa算法生成ssh密码
    执行命令ssh-keygen -t rsa，如下所示：
[root@littlelawson ~]# ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa): #这就是保存key的路径
Created directory '/root/.ssh'.#因为不存在/root/.ssh文件，所以创建一个新的文件
Enter passphrase (empty for no passphrase): #不用输入
Enter same passphrase again: 
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:
c5:04:34:16:71:86:78:e8:3e:66:16:3a:e7:33:42:fc root@littlelawson
The key's randomart image is:
+--[ RSA 2048]----+
|       +B=+      |
|      o.o*       |
|     . .  o      |
|      o  .       |
|   . o .S        |
|    = B          |
|   . O .         |
|    . E          |
|     . o         |
+-----------------+
  • step 03查看.ssh文件夹下的内容，并验证是否成功生成密钥对
[root@littlelawson .ssh]# ll
total 8
-rw-------. 1 root root 1675 Jun 17 23:00 id_rsa
-rw-r--r--. 1 root root  399 Jun 17 23:00 id_rsa.pub  #需要发送到服务器的公钥
  • step 04.将公钥发送到（需要登录到的那台）服务器【在这里，因为我需要登录本机，即root@littlelawson这台机器】【注：这里的littleawson是我机器的主机名】
[root@littlelawson .ssh]# ssh-copy-id root@littlelawson
The authenticity of host 'littlelawson (192.168.211.3)' can't be established.
RSA key fingerprint is 93:5e:0a:d0:7c:6d:46:be:94:ad:9a:f0:67:12:d9:07.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added 'littlelawson,192.168.211.3' (RSA) to the list of known hosts.
root@littlelawson's password: 
Now try logging into the machine, with "ssh 'root@littlelawson'", and check in:

  .ssh/authorized_keys

to make sure we haven't added extra keys that you weren't expecting.
  • step 05.检验公钥是否传递成功【当前客户端生成的公钥会传递到（需连接到的那台）服务器的.ssh/authorized_keys文件下】
[root@littlelawson .ssh]# cat id_rsa.pub 
ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEA0mOqjW1LlPZwdKIhp7MW4rNqHzi58MrKeRx1Af5QQWcJBveM5jg6lAlrJSrpERqmobUtoOzAA1cGw+58ba5HCwh/T6IXe4kIPJQA78JAo/8FnOAJfRpOW80CNGbk/XP+E89wGImBN4dKR6a2tL56ZggTJfYvqhQ30Ij5XyQQwEnf9663xn96SePqCvLaSGtuFkrOgmHZSxZQ/XlNFghbkwzDSprKe92FDrTSTbrjaP3/9yKnsNR7lxPMbmHSCqoOPlEaKXjucuFNf+hDE3DJyqY1jOs2pym4Ad+zn4kGMQm5BeZ1fpCS9+M9iuAPjR2QdszYkg8Mt4RM63o9SXX4Tw== root@littlelawson

[root@littlelawson .ssh]# cat authorized_keys 
ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEA0mOqjW1LlPZwdKIhp7MW4rNqHzi58MrKeRx1Af5QQWcJBveM5jg6lAlrJSrpERqmobUtoOzAA1cGw+58ba5HCwh/T6IXe4kIPJQA78JAo/8FnOAJfRpOW80CNGbk/XP+E89wGImBN4dKR6a2tL56ZggTJfYvqhQ30Ij5XyQQwEnf9663xn96SePqCvLaSGtuFkrOgmHZSxZQ/XlNFghbkwzDSprKe92FDrTSTbrjaP3/9yKnsNR7lxPMbmHSCqoOPlEaKXjucuFNf+hDE3DJyqY1jOs2pym4Ad+zn4kGMQm5BeZ1fpCS9+M9iuAPjR2QdszYkg8Mt4RM63o9SXX4Tw== root@littlelawson
5.验证

如下开启hadoop环境，如果没有配置ssh免密登录，每次启动新节点都需要输入密码。

[root@littlelawson sbin]# ./start-all.sh
This script is Deprecated. Instead use start-dfs.sh and start-yarn.sh
Starting namenodes on [littlelawson]
littlelawson: starting namenode, logging to /usr/local/hadoop-2.6.4/logs/hadoop-root-namenode-littlelawson.out
littlelawson: starting datanode, logging to /usr/local/hadoop-2.6.4/logs/hadoop-root-datanode-littlelawson.out
Starting secondary namenodes [0.0.0.0]
The authenticity of host '0.0.0.0 (0.0.0.0)' can't be established.
RSA key fingerprint is 93:5e:0a:d0:7c:6d:46:be:94:ad:9a:f0:67:12:d9:07.
Are you sure you want to continue connecting (yes/no)? yes
0.0.0.0: Warning: Permanently added '0.0.0.0' (RSA) to the list of known hosts.
0.0.0.0: starting secondarynamenode, logging to /usr/local/hadoop-2.6.4/logs/hadoop-root-secondarynamenode-littlelawson.out
starting yarn daemons
starting resourcemanager, logging to /usr/local/hadoop-2.6.4/logs/yarn-root-resourcemanager-littlelawson.out
littlelawson: starting nodemanager, logging to /usr/local/hadoop-2.6.4/logs/yarn-root-nodemanager-littlelawson.out

查看是否完全启动：

[root@littlelawson sbin]# jps
3552 Jps
2900 DataNode
3239 ResourceManager
3335 NodeManager
2809 NameNode
3085 SecondaryNameNode
6.注
  • ssh-copy-id -p [port] 可以指定ssh服务的端口号
  • 配置免密登录时，不仅要设置到别的机器的登录，也要设置到本地的免密登录。切记！