Error: Permission denied (publickey)

原文地址：https://help.github.com/articles/error-permission-denied-publickey/

A "Permission denied" error means that the server rejected your connection. There could be several reasons why, and the most common examples are explained below.

Should the sudo command be used with Git?

You should not be using the sudo command with Git. If you have a very good reason you must usesudo, then ensure you are using it with every command (it's probably just better to use su to get a shell as root at that point). If you generate SSH keys without sudo and then try to use a command like sudo git push, you won't be using the same keys that you generated.

Check that you are connecting to the correct server

Typing is hard, we all know it. Pay attention to what you type; you won't be able to connect to "githib.com" or "guthub.com". In some cases, a corporate network may cause issues resolving the DNS record as well.

To make sure you are connecting to the right domain, you can enter the following command:

ssh -vT [email protected]
# OpenSSH_5.6p1, OpenSSL 0.9.8r 8 Feb 2011
# debug1: Reading configuration data /Users/you/.ssh/config
# debug1: Reading configuration data /etc/ssh_config
# debug1: Applying options for *
# debug1: Connecting to github.com [192.30.252.131] port 22.

Note the IP address (the numbers within the [ ] brackets). The connection should be made to a GitHub IP address, on port 22, unless you're overriding settings to use SSH over HTTPS.

Always use the "git" user

All connections must be made as the "git" user. If you try to connect with your GitHub username, it will fail:

ssh -T [email protected]
# Permission denied (publickey).

Instead, you should verify your connection by typing:

ssh -T [email protected]
# Hi username! You've successfully authenticated...

Make sure you have a key that is being used

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.

1. 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
   

2. Verify that you have a private key generated and loaded into SSH:

   ssh-add -l
   # 2048 a0:dd:42:3c:5a:9d:e4:2a:21:52:4e:78:07:6e:c8:4d /Users/you/.ssh/id_rsa (RSA)
   

The ssh-add command should print out a long string of numbers and letters. If it does not print anything, you will need to generate a new SSH key and associate it with GitHub.

Tip: On most systems the default private keys (~/.ssh/id_rsa, ~/.ssh/id_dsa and ~/.ssh/identity) are automatically added to the SSH authentication agent. You shouldn't need to run ssh-add path/to/key unless you override the file name when you generate a key.

Getting more details

You can also check that the key is being used by trying to connect to [email protected]:

ssh -vT [email protected]
# ...
# debug1: identity file /Users/you/.ssh/id_rsa type -1
# debug1: identity file /Users/you/.ssh/id_rsa-cert type -1
# debug1: identity file /Users/you/.ssh/id_dsa type -1
# debug1: identity file /Users/you/.ssh/id_dsa-cert type -1
# ...
# debug1: Authentications that can continue: publickey
# debug1: Next authentication method: publickey
# debug1: Trying private key: /Users/you/.ssh/id_rsa
# debug1: Trying private key: /Users/you/.ssh/id_dsa
# debug1: No more authentication methods to try.
# Permission denied (publickey).

In that example, we did not have any keys for SSH to use. The "-1" at the end of the "identity file" lines means SSH couldn't find a file to use. Later on, the "Trying private key" lines also indicate that no file was found. If a file existed, those lines would be "1" and "Offering public key", respectively:

ssh -vT [email protected]
# ...
# debug1: identity file /Users/you/.ssh/id_rsa type 1
# ...
# debug1: Authentications that can continue: publickey
# debug1: Next authentication method: publickey
# debug1: Offering RSA public key: /Users/you/.ssh/id_rsa

Verify the public key is attached to your account

You must provide your public key to GitHub to establish a secure connection.

1. Open the command line.

2. Start SSH agent in the background.

   ssh-agent -s
   # Agent pid 59566
   

3. Enter ssh-add -l and take note of the resulting fingerprint:

   ssh-add -l
   # 2048 a0:dd:42:3c:5a:9d:e4:2a:21:52:4e:78:07:6e:c8:4d /Users/USERNAME/.ssh/id_rsa (RSA)
   

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

5. In the user settings sidebar, click SSH keys.

6. Compare the list of SSH keys with the output from ssh-add -l.

If you don't see your public key in GitHub, you'll need to add your SSH key to GitHub to associate it with your computer.