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(待翻译)github入门之遇到SSH Permission Denied问题的原因和解决

2015-08-25 21:35 477 查看
         安装好Github之后,要在一台电脑上使用github从服务器上clone一个项目,则必须确保该机器的SSH指纹加入了你的Github账号设置中。如果没有设置的话,则会显示:严重错误,权限拒绝等提示。

         将机器指纹加入设置的过程,其实相当于认证账号,实现免密码登录的过程。生成一个机器的公有密钥提供给Github记住,一旦机器以对应的私有密钥身份访问Github时,就会与公钥进行配对解码,进而获得认证。

         密钥的生成过程如下:(来自Github官网,待翻译)


Generating SSH key

SSH keys are a way to identify trusted computers, without involving passwords. The steps below will walk you through generating an SSH key and adding the public key to your GitHub account.

We recommend that you regularly review
your SSH keys list and revoke any that haven't been used in a while.

Tip: If you have GitHub
for Windows installed, you can use it to clone repositories and not deal with SSH keys. It also comes with the Git Bash tool, which is the preferred way of running 
git
 commands on Windows.


Step
1: Check for SSH keys

First, we need to check for existing SSH keys on your computer. Open Git
Bash and enter:
ls -al ~/.ssh
# Lists the files in your .ssh directory, if they exist


Check the directory listing to see if you already have a public SSH key. By default, the filenames of the public keys are one of the following:

id_dsa.pub

id_ecdsa.pub

id_ed25519.pub

id_rsa.pub

If you see an existing public and private key pair listed (for example id_rsa.pub and id_rsa)
that you would like to use to connect to GitHub, you can skip Step 2 and
go straight to Step 3.

Tip: If you receive an error that ~/.ssh doesn't
exist, don't worry! We'll create it in Step 2.


Step
2: Generate a new SSH key

With Git Bash still
open, copy and paste the text below. Make sure you substitute in your GitHub email address.
ssh-keygen -t rsa -b 4096 -C "your_email@example.com"
# Creates a new ssh key, using the provided email as a label
# Generating public/private rsa key pair.


We strongly suggest keeping the default settings as they are, so when you're prompted to "Enter a file in which to save the key", just press Enter to
continue.
# Enter file in which to save the key (/Users/you/.ssh/id_rsa): [Press enter]


You'll be asked to enter a passphrase.
# Enter passphrase (empty for no passphrase): [Type a passphrase]
# Enter same passphrase again: [Type passphrase again]


Tip: We strongly recommend a very good, secure passphrase. For more information,
see "Working
with SSH key passphrases".

After you enter a passphrase, you'll be given the fingerprint, or id,
of your SSH key. It will look something like this:
# Your identification has been saved in /Users/you/.ssh/id_rsa.
# Your public key has been saved in /Users/you/.ssh/id_rsa.pub.
# The key fingerprint is:
# 01:0f:f4:3b:ca:85:d6:17:a1:7d:f0:68:9d:f0:a2:db your_email@example.com



Step
3: Add your key to the ssh-agent

To configure the ssh-agent program
to use your SSH key:

If you have GitHub
for Windows installed, you can use it to clone repositories and not deal with SSH keys. It also comes with the Git Bash tool, which is the preferred way of running 
git
 commands on Windows.

Ensure ssh-agent is enabled:

If you are using Git Bash, turn on ssh-agent:
# start the ssh-agent in the background
ssh-agent -s
# Agent pid 59566


If you are using another terminal prompt, such as msysgit,
turn on ssh-agent:
# start the ssh-agent in the background
eval $(ssh-agent -s)
# Agent pid 59566


Add your SSH key to the ssh-agent:
ssh-add ~/.ssh/id_rsa


Tip: If you didn't generate a new SSH key in Step
2, and used an existing SSH key instead, you will need to replaceid_rsa in
the above command with the name of your existing private key file.


Step
4: Add your SSH key to your account

To configure your GitHub account to use your SSH key:

Copy the SSH key to your clipboard. If your key is named 
id_dsa.pub
id_ecdsa.pub
 or
id_ed25519.pub
, then change the filename below from id_rsa.pub to
the one that matches your key:
clip < ~/.ssh/id_rsa.pub
# Copies the contents of the id_rsa.pub file to your clipboard


Warning: It's important to copy the key exactly without adding newlines
or whitespace.

Add the copied key to GitHub:


In
the top right corner of any page, click your profile photo, then click Settings.


In
the user settings sidebar, click SSH keys.


Click Add
SSH key.

In the Title field, add a descriptive label for the new key. For example, if you're using a personal Mac, you might call this key "Personal MacBook Air".


Paste
your key into the "Key" field.


Click Add
key.

Confirm the action by entering your GitHub password.


Step
5: Test the connection

To make sure everything is working, you'll now try to SSH into GitHub. When you do this, you will be asked to authenticate this action using your password, which is the SSH key passphrase you created earlier.

Open Git Bash and
enter:
ssh -T git@github.com
# Attempts to ssh to GitHub


You may see this warning:
# The authenticity of host 'github.com (207.97.227.239)' can't be established.
# RSA key fingerprint is 16:27:ac:a5:76:28:2d:36:63:1b:56:4d:eb:df:a6:48.
# Are you sure you want to continue connecting (yes/no)?


Verify the fingerprint in the message you see matches the following message, then type 
yes
:
# Hi username! You've successfully authenticated, but GitHub does not
# provide shell access.


If the username in the message is yours, you've successfully set up your SSH key!

If you receive a message about "access denied," you can read
these instructions for diagnosing the issue.

If you're switching from HTTPS to SSH, you'll now need to update your remote repository URLs. For more information, see Changing
a remote's URL.
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