Generate RSA keys with SSH by using PuTTYgen
- Ssh-2 Rsa Key Generator
- Generate Ssh-2 Rsa Key Linux
- Generate Ssh 2 Rsa Key For Windows 7
- Generate Ssh-2 Rsa Key Mac
One effective way of securing SSH access to your cloud server is to usea public-private key pair. This means that a public key is placed onthe server and a private key is placed on your local workstation.Using a key pair makes it impossible for someone to log in by using justa password, as long as you set up SSH to deny password-basedauthentication.
This article provides steps for generating RSA keys by using PuTTYgen onWindows for secure SSH authentication with OpenSSH.
Generate keys
In Windows, use PuTTYgen to generate your public and private keys.
- If needed, download PuTTYgen from the PuTTY download page.(PuTTYgen might have been installed previously with PuTTY or WinSCP.)
- Launch the program, and then click the Generate button.The program generates the keys for you.
- Enter a unique key passphrase in the Key passphrase andConfirm passphrase fields.For additional information about using passphrases,see Log in with a SSH Private Key on Windows.
- Save the public and private keys by clicking the Save public keyand Save private key buttons.
- From the Public key for pasting into OpenSSH authorized_keys filefield at the top of the window, copy all the text (starting with ssh-rsa)to your clipboard by pressing Ctrl-C.You need this key available on your clipboard to paste eitherinto the public key tool in the Control Panel or directly into theauthorized keys on your cloud server.
How I create RSA key and enable SSH access in Cisco VG202, in a Cisco router I use the next commands(but in a VG not exists): conf t crypto key generate rsa modulus 1024 ip domain-name domain-name ip ssh version 2 ip ssh time-out 120 ip ssh authentication-retries 3 line vty 0 4 transport input telne. One way to create the SSH version 2 RSA2 User Identity Key is by using our User Identity Key create wizard through IBM Sterling B2B Integrator dashboard as below instructions shows: 1. Login as an admin user 2. Click Trading Partner SSH User Identity Key Create, Go! Enter Key Name 4. Select SSH-RSA as the Key Type 5. Select 2048 as the Key Length 6. Ensure that the Enable check box is checked. Oct 05, 2007 Generating public keys for authentication is the basic and most often used feature of ssh-keygen. Ssh-keygen can generate both RSA and DSA keys. RSA keys have a minimum key length of 768 bits and the default length is 2048. Aug 19, 2019 1. To manually add the public SSH key to the remote machine, you first need to open the content from the /.ssh/idrsa.pub file: cat /.ssh/idrsa.pub. As in the image below, the key starts with ssh-rsa and ends with the username of the local computer and hostname of the remote machine.
Use the key pair
You can use the RSA key pair in the following ways.
Specify your SSH key when creating a new cloud server
When you create a cloud server, you can assign a public key from the list of keys.If your key is not already in the list, you may add it, and then assign it.
Add a new public key to the list
Generating key pairs for SSH 2.0 requires generating an RSA key pair and a DSA key pair. About this task If you use SSH 2.0 clients other than OpenSSH, you might have to edit the public key. Jun 22, 2012 SSH keys provide a more secure way of logging into a virtual private server with SSH than using a password alone. With SSH keys, users can log into a server without a password. This tutorial explains how to generate, use, and upload an SSH Key Pair.
- Under Advanced Options on the Create Server page, click Manage SSHKeys.
- Select public key for the cloud server from the SSH Keys listand click Add Public Key.
- Enter the key name, select the region, and paste the entire publickey into the Public Key field. Then click Add Public Key.
- Go back to the Create Server page, and confirm that your key is listedin the SSH Key list.
Assign a public key
- Under Advanced Options on the Create Server page, select the publickey you want to use from the SSH key drop-down menu.
- When you are done specifying the all the other details for the server,click Create Server.
Assign your SSH Key to an existing cloud server
To make use of your newly generated RSA key pair, you must tell PuTTY touse it when connecting to your cloud server.
- To edit the file (or create it), run the following command on the cloud server:
- Paste the text onto its own line in the file.You must have the key available in your clipboard to paste it. The key and itsassociated text (the ssh-rsa identified at the start and the comment at the end)must be on one line in the file. If the text is word-wrapped onto multiple linesan error might occur when connecting.
- If you created the authorized_keys file, change its permissionsafter you’re done editing it by running the following command:
- Open PuTTY, and go to the SSH > Auth section.
- Browse to the location of the key file, and load the private key.
- Go to the Session page, and save the session. This saves the configurationso that PuTTY uses the key every time that you connect to your cloudserver.
After you save your session, your key is loaded automatically when youconnect to your server.
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Contents
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Parent page: Internet and Networking >> SSH
Public key authentication is more secure than password authentication. This is particularly important if the computer is visible on the internet. If you don't think it's important, try logging the login attempts you get for the next week. My computer - a perfectly ordinary desktop PC - had over 4,000 attempts to guess my password and almost 2,500 break-in attempts in the last week alone.
With public key authentication, the authenticating entity has a public key and a private key. Each key is a large number with special mathematical properties. The private key is kept on the computer you log in from, while the public key is stored on the .ssh/authorized_keys file on all the computers you want to log in to. When you log in to a computer, the SSH server uses the public key to 'lock' messages in a way that can only be 'unlocked' by your private key - this means that even the most resourceful attacker can't snoop on, or interfere with, your session. As an extra security measure, most SSH programs store the private key in a passphrase-protected format, so that if your computer is stolen or broken in to, you should have enough time to disable your old public key before they break the passphrase and start using your key. Wikipedia has a more detailed explanation of how keys work.
Public key authentication is a much better solution than passwords for most people. In fact, if you don't mind leaving a private key unprotected on your hard disk, you can even use keys to do secure automatic log-ins - as part of a network backup, for example. Different SSH programs generate public keys in different ways, but they all generate public keys in a similar format:
Key-based authentication is the most secure of several modes of authentication usable with OpenSSH, such as plain password and Kerberos tickets. Key-based authentication has several advantages over password authentication, for example the key values are significantly more difficult to brute-force, or guess than plain passwords, provided an ample key length. Other authentication methods are only used in very specific situations.
SSH can use either 'RSA' (Rivest-Shamir-Adleman) or 'DSA' ('Digital Signature Algorithm') keys. Both of these were considered state-of-the-art algorithms when SSH was invented, but DSA has come to be seen as less secure in recent years. RSA is the only recommended choice for new keys, so this guide uses 'RSA key' and 'SSH key' interchangeably.
Key-based authentication uses two keys, one 'public' key that anyone is allowed to see, and another 'private' key that only the owner is allowed to see. To securely communicate using key-based authentication, one needs to create a key pair, securely store the private key on the computer one wants to log in from, and store the public key on the computer one wants to log in to.
Using key based logins with ssh is generally considered more secure than using plain password logins. This section of the guide will explain the process of generating a set of public/private RSA keys, and using them for logging into your Ubuntu computer(s) via OpenSSH.
The first step involves creating a set of RSA keys for use in authentication.
This should be done on the client.
To create your public and private SSH keys on the command-line:
You will be prompted for a location to save the keys, and a passphrase for the keys. This passphrase will protect your private key while it's stored on the hard drive:
Your public key is now available as .ssh/id_rsa.pub in your home folder.
Congratulations! You now have a set of keys. Now it's time to make your systems allow you to login with them
Choosing a good passphrase
You need to change all your locks if your RSA key is stolen. Otherwise the thief could impersonate you wherever you authenticate with that key.
An SSH key passphrase is a secondary form of security that gives you a little time when your keys are stolen. If your RSA key has a strong passphrase, it might take your attacker a few hours to guess by brute force. That extra time should be enough to log in to any computers you have an account on, delete your old key from the .ssh/authorized_keys file, and add a new key.
Your SSH key passphrase is only used to protect your private key from thieves. It's never transmitted over the Internet, and the strength of your key has nothing to do with the strength of your passphrase.
The decision to protect your key with a passphrase involves convenience x security. Note that if you protect your key with a passphrase, then when you type the passphrase to unlock it, your local computer will generally leave the key unlocked for a time. So if you use the key multiple times without logging out of your local account in the meantime, you will probably only have to type the passphrase once.
If you do adopt a passphrase, pick a strong one and store it securely in a password manager. You may also write it down on a piece of paper and keep it in a secure place. If you choose not to protect the key with a passphrase, then just press the return when ssh-keygen asks.
Key Encryption Level
Note: The default is a 2048 bit key. You can increase this to 4096 bits with the -b flag (Increasing the bits makes it harder to crack the key by brute force methods).
Password Authentication
The main problem with public key authentication is that you need a secure way of getting the public key onto a computer before you can log in with it. If you will only ever use an SSH key to log in to your own computer from a few other computers (such as logging in to your PC from your laptop), you should copy your SSH keys over on a memory stick, and disable password authentication altogether. If you would like to log in from other computers from time to time (such as a friend's PC), make sure you have a strong password.
The key you need to transfer to the host is the public one. If you can log in to a computer over SSH using a password, you can transfer your RSA key by doing the following from your own computer:
Where <username> and <host> should be replaced by your username and the name of the computer you're transferring your key to.
Due to this bug, you cannot specify a port other than the standard port 22. You can work around this by issuing the command like this: ssh-copy-id '<username>@<host> -p <port_nr>'. If you are using the standard port 22, you can ignore this tip.
Another alternative is to copy the public key file to the server and concatenate it onto the authorized_keys file manually. It is wise to back that up first:
You can make sure this worked by doing:
You should be prompted for the passphrase for your key:
Enter passphrase for key '/home/<user>/.ssh/id_rsa': |
Enter your passphrase, and provided host is configured to allow key-based logins, you should then be logged in as usual.
Encrypted Home Directory
If you have an encrypted home directory, SSH cannot access your authorized_keys file because it is inside your encrypted home directory and won't be available until after you are authenticated. Therefore, SSH will default to password authentication.
To solve this, create a folder outside your home named /etc/ssh/<username> (replace '<username>' with your actual username). This directory should have 755 permissions and be owned by the user. Move the authorized_keys file into it. The authorized_keys file should have 644 permissions and be owned by the user.
Then edit your /etc/ssh/sshd_config and add:
Finally, restart ssh with:
The next time you connect with SSH you should not have to enter your password.
username@host's password:
If you are not prompted for the passphrase, and instead get just the
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prompt as usual with password logins, then read on. There are a few things which could prevent this from working as easily as demonstrated above. On default Ubuntu installs however, the above examples should work. If not, then check the following condition, as it is the most frequent cause:
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On the host computer, ensure that the /etc/ssh/sshd_config contains the following lines, and that they are uncommented;
If not, add them, or uncomment them, restart OpenSSH, and try logging in again. If you get the passphrase prompt now, then congratulations, you're logging in with a key!
Permission denied (publickey)
If you're sure you've correctly configured sshd_config, copied your ID, and have your private key in the .ssh directory, and still getting this error:
Permission denied (publickey). |
Chances are, your /home/<user> or ~/.ssh/authorized_keys permissions are too open by OpenSSH standards. You can get rid of this problem by issuing the following commands:
Error: Agent admitted failure to sign using the key.
This error occurs when the ssh-agent on the client is not yet managing the key. Issue the following commands to fix:
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This command should be entered after you have copied your public key to the host computer.
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Debugging and sorting out further problems
The permissions of files and folders is crucial to this working. You can get debugging information from both the client and server.
if you think you have set it up correctly , yet still get asked for the password, try starting the server with debugging output to the terminal.
To connect and send information to the client terminal
No matter how your public key was generated, you can add it to your Ubuntu system by opening the file .ssh/authorized_keys in your favourite text editor and adding the key to the bottom of the file. You can also limit the SSH features that the key can use, such as disallowing port-forwarding or only allowing a specific command to be run. This is done by adding 'options' before the SSH key, on the same line in the authorized_keys file. For example, if you maintain a CVS repository, you could add a line like this:
When the user with the specified key logged in, the server would automatically run /usr/bin/cvs server, ignoring any requests from the client to run another command such as a shell. For more information, see the sshd man page. /755