Skip to content

SSH.md

Latest commit

 

History

History
155 lines (111 loc) · 4.76 KB

SSH.md

File metadata and controls

155 lines (111 loc) · 4.76 KB
Raw

Setting up SSH keys

The following are few instructions to setup your SSH keys mainly for GNU/Linux OS but should also work for windows. Remember to use your $USERNAME and email credentials when necessary.

1. GNU/Linux

To create your SSH keys you can do either with ed25519 or RSA 4096

1.1 Using ed25519

Open a terminal in your GNU/Linux OS and follow this instructions: NB. ed25519 is from a branch of cryptography called "elliptic curve cryptography (ECC).

  1. generate key using ed25519
MACHINE=$(hostnamectl | awk -F': ' '/Static hostname/ {print $2}')
ssh-keygen -o -a 100 -t ed25519 -f ~/.ssh/id_ed25519_${MACHINE}

#PRESS ENTER FOR THIS LINES
Enter passphrase (empty for no passphrase): 
Enter same passphrase again:
  1. Adding your SSH key to the ssh-agent
eval "$(ssh-agent -s)"
ssh-add ~/.ssh/id_ed25519_${MACHINE}
  1. Adding a new SSH key to your GitHub account
sudo apt-get install xclip
xclip -sel clip < ~/.ssh/id_ed25519_${MACHINE}.pub

  1. Add your New SSH Use a name, (e.g. ed25519_machine_OSversion), select authentification key and add it in https://github.com/settings/keys

  2. Testing your SSH connection

ssh -T git@github.com
#The authenticity of host 'github.com (140.....)' can't be established.
#ECDSA key fingerprint is SHA256:.....
#Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
#Warning: Permanently added 'github.com,140.....' (ECDSA) to the list of known hosts.
Hi mxochicale! You've successfully authenticated, but GitHub does not provide shell access.
  1. Set Up Git user name and email
git config --global user.name "mxochicale"
git config --global user.email "mxochicale@users.noreply.github.com"

1.1.1 Extra: adding a DEPLOY KEY

Create a new secret variable called DEPLOY_KEY in https://github.com/REPOSITORY_USER/REPOSITORY_NAME/settings/secrets where the value looks like the below lines and is taken from id_rsa with

xclip -selection clipboard < ~/.ssh/id_rsa

-----BEGIN RSA PRIVATE KEY-----
...
-----END RSA PRIVATE KEY-----

1.2 Using RSA 4096

Open a terminal in your GNU/Linux OS and follow this instructions:

  1. generate key using RSA
ssh-keygen -m PEM -t rsa -b 4096 -C "your-email@domain.com"

Press only enter twice until you see a graphical code

  1. Adding your SSH key to the ssh-agent
eval "$(ssh-agent -s)"
ssh-add ~/.ssh/id_rsa
  1. Adding a new SSH key to your GitHub account
sudo apt-get install xclip
xclip -selection clipboard < ~/.ssh/id_rsa.pub
#in_windows clip id_rsa.pub

Add a new SSH key by going to https://github.com/settings/keys and pasting the key with a descriptive new title:

Title: New Key

Key type (Authentication Key or Siging Key):
ssh-rsa A............................== your-email@domain.com
  1. Testing your SSH connection

When copying and pasting ssh -T git@github.com type yes to authorise the connection:

ssh -T git@github.com
The authenticity of host 'github.com (000.00.000.0)' can't be established.
RSA key fingerprint is ....:.....
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
Warning: Permanently added 'github.com,000.00.000.0' (RSA) to the list of known hosts.
Hi mxochicale! You've successfully authenticated, but GitHub does not provide shell access.

2. Windows

Open a terminal which is based on Gitbash

GitBash!

Also in windows use cat instead of xclip for copying keys

cat ~/.ssh/id_rsa.pub

3. Warnings

To solve "Warning: the ECDSA host key for 'github.com' differs from the key for the IP address", you need to remove old keys for GitHub from your know_host file

ssh-keygen -R github.com

If you are still getting the warning you need to delete the records from the IP, as the following example

ssh-keygen -R 140.82.114.3

4. Reasons to chose ed over RSA

Security: people tend to like ECC over RSA because the keys are smaller and the computations are faster for the same security level. Below is a table showing the security level comparison of RSA (labeled as Integer Factorization, or IF) vs ECC [source]. You can see that ECC keys really do get the same job done with a smaller key.

refererences