There are many options of running the SSH on Macs, however we recommend running this from the terminal command line as this is the easiest. To get started, you need to open the Terminal application which is found in Applications Utilities Directory, but you can also launch this by hitting cmd+spacebar and typing “Terminal” into the search box and then return. If these files exist, then you have already created SSH keys. You can overwrite the keys with the following commands, or skip this step and go to configuring SSH keys to reuse these keys. Create your SSH keys with the ssh-keygen command from the bash prompt. This command will create a 2048-bit RSA key for use with SSH. For more background and examples, see Detailed steps to create SSH key pairs. For additional ways to generate and use SSH keys on a Windows computer, see How to use SSH keys with Windows on Azure. Supported SSH key formats. Azure currently supports SSH protocol 2 (SSH-2) RSA public-private key pairs with a minimum length of 2048 bits. When you generate your keys, you will use ssh-keygen to store the keys in a safe location so you can bypass the login prompt when connecting to your server. To generate SSH keys in Mac OS X, follow these steps: Enter the following command in the Terminal window. Ssh-keygen -t rsa This starts the key generation process. How to use PuTTY SSH keys with the built-in OpenSSH. If you have a PuTTY.ppk format private key and want to use it with the built-in OpenSSH on Mac on the command line or in scripts, you can use the following commands. First, install PuTTY for Mac using brew install putty or port install putty (see below).
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.
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):
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 command
ssh-copy-id
can be used to install an authorized key on the server.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:
Mac Ssh Public Key
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:
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Related Articles
First cool thing that everybody knows already: Mac OSX is based on Unix so you get ssh out of the box.
Second cool thing you may not know: OS X 10.5 actually also comes with an ssh key agent (ssh-agent). That means that, without any additional software (like PuTTY Agent on Windows...), Mac OSX can actually load an encrypted private key into memory and remember it for all subsequent connections...
Third cool thing that almost seems too good to be true: ssh-agent can store the passwords of the encrypted keys into your keychain. Than means that you have to tell it once to remember the decryption password for your key(s) like this:
ssh-add -K .ssh/id_whatever_your_rivate_key_is
And next time you log into your mac and try to ssh somewhere, your private key will be loaded automagically (as long as your keychain is unlocked of course).
Very groovy!!
Ssh Add Key Mac
This entry was posted on Dec 21 2008 at 02:34 by admin and is filed under Linux stuff, Mac stuff. Tags: howto, mac os x, ssh, terminal