在尝试安装hadoop离线版的时候，在安装cygwin64，并对其sshd服务进行免密化的时候出现了问题，老是提示需要输入密码。
就在这里记录一下解决操作。
文章写得有点小白，而且很详细，佬看了可能有点上火，还请各位大佬见谅。
问题发生环境：已经安装了cygwin，安装了ssh相关的服务，即openssh组件等，并且进行了cygwin环境变量的配置，下面就对免密的具体操作进行介绍
PS：如果你是已经安装了ssh的相关服务，并且在配置免密的过程中出现免密失败的问题，我建议你参考下面这篇文章，去把sshd服务卸了重新配。
（执行到第三个命令即可。如果你已经全部执行才看到这句话，抱歉，我的锅，再次重新卸了配吧。）
https://blog.csdn.net/swazer_z/article/details/22154203
如果你在重新配的过程中，执行cygrunsrv -R sshd指令出现1060错误码的时候,请手动进入服务，找到CYGWIN服务，启动它即可.
$ cygrunsrv -R sshd cygrunsrv: Error starting a service: OpenSCManager: Win32 error 1060: #1060错误码
如果在安装过程中，出现了这个错误，请用管理员身份重新启动cygwin64进行操作。
cygrunsrv: Error removing a service: OpenSCManager: Win32 error 5:
#ssh的免密操作
执行指令顺序：（注意，要是实在不会弄，就看我下面一步步来，如果没把把握解决就别直接粘贴指令完事）
ssh-host-config ssh-keygen cd ~/.ssh cat id_rsa.pub >> authorized_keys ssh localhost #如果你在这里启动，发现遇到了 # WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED！ #那么就看我下面的解决方式，你遇到这个情况的原因就是你之前装了ssh的服务，识别ip出错了。
第一步：
"""此处如果你是之前配过，那么前面几个叫你overwrite，你填yes就是了。""" """然后最关键的一点就是Should privilege separation be used? (yes/no) 选择：no，具体的原因我会把大佬的文章放下面。"""
$ ssh-host-config *** Info: Generating missing SSH host keys *** Query: Overwrite existing /etc/ssh_config file? (yes/no) yes *** Info: Creating default /etc/ssh_config file *** Query: Overwrite existing /etc/sshd_config file? (yes/no) yes *** 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) yes *** 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/READ ME.privsep. *** Query: Should privilege separation be used? (yes/no) no *** Info: Updating /etc/sshd_config file *** Info: Sshd service is already installed. *** Info: Host configuration finished. Have fun!
如果这个地方，你执行ssh-host-config出现了下面这个错误的话，你就进到服务里面，找到CYGWIN，把这个服务给关了，在重新执行这个指令就行。
第二步，我是之前装过的，所以说overwrite我就直接选y了
$ ssh-keygen Generating public/private rsa key pair. Enter file in which to save the key (/home/Neroism/.ssh/id_rsa): /home/Neroism/.ssh/id_rsa already exists. Overwrite (y/n)? y Enter passphrase (empty for no passphrase): Enter same passphrase again: Your identification has been saved in /home/Neroism/.ssh/id_rsa Your public key has been saved in /home/Neroism/.ssh/id_rsa.pub The key fingerprint is: SHA256:DtLaosz1JHxmprtmABoAopLaY4zCDbVocpVp6gS6Cmc Neroism@DESKTOP-9SRJK1N The key's randomart image is: +---[RSA 3072]----+ |+ ..o | |=.o.= | |B=.+ | |X== . | |=B=.. o S | |=.Eo + o | |oo .* B . | |.o oo@ | | +o+o. | +----[SHA256]-----+
第三步，进ssh目录
$ cd ~/.ssh #没什么讲的，就是进到ssh目录里面
$ ls -l #这里我看了下目录里面文件的情况，不一定都是这样 #但是id_rsa和id_rsa.pub文件是一定有的，authorized_keys我们后面会生成 #kown_hosts可以不管，一般情况下你没尝试配过都是没有的。 total 7 -rw-r--r-- 1 Neroism None 577 Nov 9 20:00 authorized_keys -rw------- 1 Neroism None 2610 Nov 10 18:53 id_rsa -rw-r--r-- 1 Neroism None 577 Nov 10 18:53 id_rsa.pub -rw-r--r-- 1 Neroism None 91 Nov 9 20:01 known_hosts
第四步，将id_rsa.pub内的内容写到authorized_keys里面，没有这个文件会生成。
$ cat id_rsa.pub >> authorized_keys
第五步，最关键的一步，这个地方可能会出现两种情况，你执行ssh localhost，一种是你成功启动了，问你要不要启动，填yes即可，下面也会对这个情况进行介绍；另外一种情况就是，启动不成果，报出下面情况。
$ ssh localhost @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY! Someone could be eavesdropping on you right now (man-in-the-middle attack)! It is also possible that a host key has just been changed. The fingerprint for the ED25519 key sent by the remote host is SHA256:OqSKpJS0opF4pEEKWJaj19UQPKar/ZJczE7IfDcgJV0. Please contact your system administrator. Add correct host key in /home/Neroism/.ssh/known_hosts to get rid of this message. Offending ED25519 key in /home/Neroism/.ssh/known_hosts:1 Host key for localhost has changed and you have requested strict checking. Host key verification failed.
这个时候怎么解决呢，就执行vi ~/.ssh/known_hosts，把这个文件打开，然后将文件内，包含ip的所有部分删掉，这里我用的是离线安装方式，所以说删掉的就是localhost部分。
下面这图是一个大佬的图，可以看到他是一个ip接了很多你不知道的乱码，这个码就是你的密钥，你需要把整个一块全部删掉。
这个图是我的，已经配置好了，只是给你们看一下，大概内容是这个样子的。在删掉后，别急着退出，打出”：“然后输入wq，保存就行。
然后你再启动ssh localhost，就可以了(上面没出现我说的这个问题的，直接跳这里来。)
$ ssh localhost #如果没出现上面情况，跳到这个地方 The authenticity of host 'localhost (::1)' can't be established. ED25519 key fingerprint is SHA256:OqSKpJS0opF4pEEKWJaj19UQPKar/ZJczE7IfDcgJV0. This key is not known by any other names Are you sure you want to continue connecting (yes/no/[fingerprint])? yes Warning: Permanently added 'localhost' (ED25519) to the list of known hosts. $ ssh localhost Last login: Wed Nov 10 18:56:22 2021 from ::1
下面是我参考的几位大佬的文章：
从头配置：
https://blog.csdn.net/diogy/article/details/50865908
问题指令cygrunsrv -R sshd：
https://blog.csdn.net/swazer_z/article/details/22154203
问题WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!：
https://blog.csdn.net/xlgen157387/article/details/52669709
https://blog.csdn.net/wd2014610/article/details/79945424
欢迎大家不啬赐教~~
