SSH and Linux, macOS, or Unix: Set up the public and private keys for Git and CodeCommit To set up the public and private keys for Git and CodeCommit From the terminal on your local machine, run the ssh-keygen command, and follow the directions to save the file to the.ssh directory for your profile. Mac OS X includes a command-line SSH client as part of the operating system. To use it, goto Finder, and selext Go - Utilities from the top menu. Then look for Terminal. Terminal can be used to get a local terminal window, and also supports SSH connections to remote servers.
Introduction
Setting up SSH based security to access your server is a much more effective way than the use of a manual root password. Cracking the security system of a node depending on SSH keys is nearly impossible since it secures your node in a more sophisticated way by the use of encoded keys.
Why is a password-based authentication vulnerable?
A server can authenticate & grant access to the users with different access methods. The most basic of these is a password-based authentication, which is easy to use but isn’t the most secure.
Modern processing power combined with automated scripts make brute forcing a password-protected account very possible since passwords generally are not complex. SSH keys prove to be a reliable and secure alternative.
What are SSH Keys?
SSH key pairs are two cryptographically secure keys that can be used to authenticate a client to an SSH server. Each key pair consists of a public key and a private key.
The private key is retained by the client on his local machine and should be kept absolutely secret. Any compromise of the private key will allow the attacker to log into servers that are configured with the associated public key without additional authentication. As an additional precaution, the key can be encrypted on disk with a passphrase.
The public key is uploaded onto the remote server that you want to be able to log into with SSH.
When a client attempts to authenticate using SSH keys, the server can test the client on whether they are in possession of the private key. If the key-pair matches then a shell session is spawned or the requested command is executed.
How do SSH keys work
- A key pair will be generated on your local PC.
- Generating a key pair provides you with two long string of characters: a public and a private key.
- The public key will be added to your node.
- The corresponding private key pair will be saved on your local PC.
- Every time you access your node, the SSH system will look up for the private key pair of the public key added to it. The system will unlock only when the two keys match.
- You can also disable the root password after the SSH keys are set up.
Make sure that you add the public key to the servers and the private key is saved in a secure location on your PC.
Setup SSH keys – macOS
The following outlines the process of setting up key-based SSH login on Mac OS X and Mac OS X Server. To set up key-based SSH, you must generate the keys the two computers will use to establish and validate the identity of each other.
This doesn’t authorize all users of the computer to have SSH access. Keys must be generated for each user account.
Step 1 – Verification of .ssh directory
Verify that an .ssh folder exists in your home folder by entering the command-
If .ssh is listed in the output, move to next step.
If .ssh is not listed in the output, run
mkdir ~/.ssh
Change directories in the shell to the hidden .ssh directory by entering the following command:
Step 2 – Create the RSA Key Pair
Generate the public and private keys by entering the following command:
ssh-keygen -b 1024 -t rsa -f id_rsa
(The -b flag sets the length of the keys to 1,024-bits, -t indicates to use the RSA hashing algorithm, -f sets the file name as id_rsa.)
The above command will follow up with some confirmation messages
[root@e2e ~]# ssh-keygen -b 1024 -t rsa -f id_rsa
Generating public/private rsa key pair.
Enter passphrase (empty for no passphrase):
press Enter to set the passprase to null
Two files will be generated after this step.
- id_rsa (Private Key)
- id_rsa.pub (public key)
Note: Keys are equivalent to passwords so you should keep them private and protected.DO NOT SHARE YOUR PRIVATE KEY (id_rsa)
Prior to scp/ssh we have to add the identity to the user for whom we generated the key, by running
Step 3 – Copy the Public Key to your node
Now you can copy and add your public key id_rsa.pub file, to set up SSH on your node under MyAccount.
You can usually get this key by copying the results of:
Paste the results generated from id_rsa.pub to the SSH section under MyAccount.
You may add multiple SSH keys & can provide a label to each SSH key for easy identification & management purpose.
Copy the public key directly to a server (Alternate Approach)
The commandssh-copy-id
can be used to install an authorized key on the server.
Ssh On Macos Catalina
If you don’t have SSH access to the server then it will require a root password which is shared with you in the email.
Once the key has been authorized for SSH, it grants access to the server without a password.
Use a command like the following to copy SSH key:
Enter the following command to copy your public key to your Node:
This will copy your public key to the authorized_keys file on your server.
Make sure to replace xxx.xx.xx.xx with your actual Ip address and replace user with your actual username in the above command.
Once you enter the ssh-copy-id command, you will see information similar to this:
Only the public key is copied to the server. The private key should never be copied to a machine.
Modifying permissions
For an additional layer of security, modify the file permissions.
Directory .ssh should have 700 permissions and authorized_keys file should have 400 or 600 permissions. To change the permissions, use the following commands:
Now log into the remote server using ssh or scp/sftp: