通过cygwin安装openSSH

openSSH的安装是学习hadoop必不可少的一步，如果ssh装不好，hadoop的安装会进行不下去。本人初学hadoop时发现以前安装ssh走了一些弯路，现在又有了一些认识，所以重写了这篇日志，供其他需要的朋友参考。 
本文安装的版本是OpenSSH_6.7p1, OpenSSL 1.0.1j 15 Oct 2014，已经试验成功。

1. 通过cygwin安装openSSH 
cygwin怎么装就不说了，不懂的可以见另一篇博客cygwin安装

如下图添加openssh,openssl组件即可安装。 

2. 配置SSH服务

2.1.[以管理员身份运行]桌面上的Cygwin，必须的，不然没权限创建sshd服务。这点以后运行Cygwin时请作为一个常识铭记在心，后面不再赘述。

2.2 查看ssh版本号

$ ssh -V
OpenSSH_6.7p1, OpenSSL 1.0.1j 15 Oct 2014

2.3 输入

ssh-host-config

然后按照提示一步一步来

*** Info: Generating missing SSH host keys 
ssh-keygen: generating new host keys: RSA1 RSA DSA ECDSA ED25519 
*** Info: Creating default /etc/ssh_config file 
*** Info: Creating default /etc/sshd_config file

*** Info: StrictModes is set to 'yes' by default. 
*** Info: This is the recommended setting, but it requires that the POSIX 
*** Info: permissions of the user's home directory, the user's .ssh 
*** Info: directory, and the user's ssh key files are tight so that 
*** Info: only the user has write permissions. 
*** Info: On the other hand, StrictModes don't work well with default 
*** Info: Windows permissions of a home directory mounted with the 
*** Info: 'noacl' option, and they don't work at all if the home 
*** Info: directory is on a FAT or FAT32 partition. 
*** Query: Should StrictModes be used? (yes/no) no

*** Info: Privilege separation is set to 'sandbox' by default since 
*** Info: OpenSSH 6.1.  This is unsupported by Cygwin and has to be set 
*** Info: to 'yes' or 'no'. 
*** Info: However, using privilege separation requires a non-privileged account 
*** Info: called 'sshd'. 
*** Info: For more info on privilege separation read /usr/share/doc/openssh/README.privsep. 
*** Query: Should privilege separation be used? (yes/no) no 
*** Info: Updating /etc/sshd_config file

*** Query: Do you want to install sshd as a service? 
*** Query: (Say "no" if it is already installed as a service) (yes/no) yes 
*** Query: Enter the value of CYGWIN for the daemon: [] 
*** Info: On Windows Server 2003, Windows Vista, and above, the 
*** Info: SYSTEM account cannot setuid to other users -- a capability 
*** Info: sshd requires.  You need to have or to create a privileged 
*** Info: account.  This script will help you do so.

*** Info: You appear to be running Windows XP 64bit, Windows 2003 Server, 
*** Info: or later.  On these systems, it's not possible to use the LocalSystem 
*** Info: account for services that can change the user id without an 
*** Info: explicit password (such as passwordless logins [e.g. public key 
*** Info: authentication] via sshd).

*** Info: If you want to enable that functionality, it's required to create 
*** Info: a new account with special privileges (unless a similar account 
*** Info: already exists). This account is then used to run these special 
*** Info: servers.

*** Info: Note that creating a new user requires that the current account 
*** Info: have Administrator privileges itself.

*** Info: No privileged account could be found.

*** Info: This script plans to use 'cyg_server'. 
*** Info: 'cyg_server' will only be used by registered services. 
*** Query: Do you want to use a different name? (yes/no) no 
*** Query: Create new privileged user account 'cyg_server'? (yes/no) yes 
*** Info: Please enter a password for new user cyg_server.  Please be sure 
*** Info: that this password matches the password rules given on your system. 
*** Info: Entering no password will exit the configuration. 
*** Query: Please enter the password: 
*** Query: Reenter:

*** Info: User 'cyg_server' has been created with password 'cyg_server'. 
*** Info: If you change the password, please remember also to change the 
*** Info: password for the installed services which use (or will soon use) 
*** Info: the 'cyg_server' account.

*** Info: Also keep in mind that the user 'cyg_server' needs read permissions 
*** Info: on all users' relevant files for the services running as 'cyg_server'. 
*** Info: In particular, for the sshd server all users' .ssh/authorized_keys 
*** Info: files must have appropriate permissions to allow public key 
*** Info: authentication. (Re-)running ssh-user-config for each user will set 
*** Info: these permissions correctly. [Similar restrictions apply, for 
*** Info: instance, for .rhosts files if the rshd server is running, etc].

*** Info: The sshd service has been installed under the 'cyg_server' 
*** Info: account.  To start the service now, call `net start sshd' or 
*** Info: `cygrunsrv -S sshd'.  Otherwise, it will start automatically 
*** Info: after the next reboot.

*** Info: Host configuration finished. Have fun!

上面会提示创建一个用户cyg_server,并提示你输入该用户的密码，我们这里输入和用户名一样的密码cyg_server，后面会用到。 
请注意cyg_server用户的创建是强制的，没有这个用户即使sshd装好也不行的，后面使用的时候会出现Connection closed的错误，本人就在这里栽了跟头，浪费了好多时间。

2.3 好了到服务里看一下，会多出来一个CYGWIN sshd，可以把它设置成手动启动，然后我们启动它。 
 
注意下图，sshd必须要用cyg_server用户登陆的，换成“本地系统账户”是不行的。本人在这里栽了跟头，浪费了好多时间。 

2.4 系统会在Cygwin的home目录下生成一个和你windows用户名同名的目录，此处假设用户名为Administrator 
如果home目录下没有和你windows用户名同名的目录的话，尝试删除环境变量HOME再试。

3．启动OpenSSH服务的方法

A．在command控制台上启动 
net start sshd 
net stop sshd

B．在Cygwin控制台上启动 
cygwin --start sshd 
cygwin --stop sshd

4. 配置用户密码（废弃，不建议使用）

输入 
ssh-user-config

*** Query: Shall I create a SSH2 DSA identity file for you? (yes/no) yes 
** Query: Shall I create a SSH2 ECDSA identity file for you? (yes/no) yes 
以上2个问题选yes，还有一个ssh1的就不要创建了。 
注意密码必须4位以上，不然会创建失败。 
我们输入密码'password'，后面会用到。

成功的话在cygwin\home\Administrator\.ssh目录下会有如图所示的这些文件。 

5.测试（废弃，不建议使用） 
在command控制台上用 
ssh Administrator@127.0.0.1 
输入密码如果没报错，进去以后再执行ls都没问题的话，说明OpenSSH安装配置成功。

注意这里有2种输密码的方法，一种是Enter passphrase for key 'id_dsa',  'id_ecdsa',输入之前的password可以进去 
还有一种这2个密码直接敲回车，表示不输，然后会提示 
Administrator@127.0.0.1's password: 
这里注意要输入之前cyg_server用户的密码，即cyg_server也可以进去 
不行的话通过passwd Administrator命令自己改密码吧

如果还进不去，可以试试防火墙设置里面将22号端口放开，SSH服务默认使用的是22号端口。

6.秘钥方式登陆 
这种方式无需输入密码，可以直接登陆。

参考资料 
http://blog.chinaunix.net/uid-311680-id-2439725.html

6.1首先生成公钥和私钥

Administrator@PC-201308290023 ~ 
$ pwd 
/home/Administrator

Administrator@PC-201308290023 ~ 
$ ssh-keygen -t rsa 
Generating public/private rsa key pair. 
Enter file in which to save the key (/home/Administrator/.ssh/id_rsa): 
Created directory '/home/Administrator/.ssh'. 
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /home/Administrator/.ssh/id_rsa. 
Your public key has been saved in /home/Administrator/.ssh/id_rsa.pub. 
The key fingerprint is: 
0f:95:15:a7:4a:2b:f2:72:d4:e1:bd:f3:9b:c2:79:38 Administrator@PC-201308290023 
The key's randomart image is: 
+---[RSA 2048]----+ 
|            o..  | 
|           o o   | 
|          = .    | 
|         = =     | 
|      . S = .    | 
|       + +   .   | 
|      . o ..oo   | 
|       o    Eo.. | 
|             ++. | 
+-----------------+

6.2 拷贝公钥到服务器 
我们用之前的要输入密码的方式用scp命令将文件传到服务器上

C:\Users\Administrator>scp id_rsa.pub Administrator@localhost:~/.ssh 
Enter passphrase for key '/home/Administrator/.ssh/id_dsa': 
setsockopt IPV6_TCLASS 8: Protocol not available: 
id_rsa.pub                                    100%  411     0.4KB/s   00:00

6.3 将公钥的文本信息附加到服务器authorized_keys文件的末尾（用cat命令）

C:\Users\Administrator>ssh Administrator@localhost 
Enter passphrase for key '/home/Administrator/.ssh/id_dsa': 
setsockopt IPV6_TCLASS 16: Protocol not available: 
Last login: Mon May  5 21:56:42 2014 from 127.0.0.1

Administrator@PC-201308290023 ~ 
$ cd .ssh

Administrator@PC-201308290023 ~/.ssh 
$ cat id_rsa.pub >> authorized_keys

Administrator@PC-201308290023 ~/.ssh 
$ logout 
Connection to localhost closed.

如果都是在localhost一台机器做实验的话，6.2,6.3也可以简化为 
Administrator@PC-201308290023 ~ 
$ cd .ssh

Administrator@PC-201308290023 ~/.ssh 
$ cat id_rsa.pub >> authorized_keys

6.4 可以使用密钥登陆服务器了，这样就无需输入密码了。

关闭重新登录cygwin，第一次会提示

Administrator@PC-201308290023 ~ 
$ ssh localhost 
The authenticity of host 'localhost (::1)' can't be established. 
ECDSA key fingerprint is 2b:91:c2:13:ea:5c:d0:5c:9c:2f:81:b6:62:c2:fc:ee. 
Are you sure you want to continue connecting (yes/no)? yes 
Warning: Permanently added 'localhost' (ECDSA) to the list of known hosts.

再次关闭重新登录cygwin，以后就不会提示了。

Administrator@PC-201308290023 ~ 
$ ssh localhost 
Last login: Tue Nov 11 22:35:18 2014 from ::1

输入who和who am i确认一下是否成功。

Administrator@PC-201308290023 ~ 
$ who 
Administrator pty1         2014-11-11 22:35 (::1)

Administrator@PC-201308290023 ~ 
$ who am i 
Administrator pty1         2014-11-11 22:35 (::1)

7.常见错误 
Connection closed by ::1 
Error installing a service: CreateService: Win32 error 1057

这些错误是我碰到过的，碰到这些错，表示你前面安装步骤有误，比如cyg_server用户没创建，或者是你曾经输入过cygrunsrv -R sshd命令删除过sshd。 
如果是这样，那就没辙了，卸载cygwin重来吧，至少我还没找到一个好方法，但是卸载重装cygwin是有效的。

卸载方法：删除cygwin目录下的所有东东就可以了，当然，你可以保留之前download下来的安装包，节省重新下载的时间。

补充：可能将这个文件C:\cygwin64\etc\passwd里面cyg_server这个用户删掉可以解决。本文没试过，大家如果出这个错可以作为最后一根救命稻草试一下。