This article provides steps for connecting to a cloud server froma computer running Linux® or MacOS® X by using Secure Shell (SSH).It also discusses generating an SSH key and adding a public key tothe server.
SSH keys are created using a key generation tool. The SSH command line tool suite includes a keygen tool. Most git hosting providers offer guides on how to create an SSH Key. Generate an SSH Key on Mac and Linux. Both OsX and Linux operating systems have comprehensive modern terminal applications that ship with the SSH suite installed.
SSH is a protocol through which you can access your cloud server and runshell commands. You can use SSH keys to identify trusted computers withoutthe need for passwords and to interact with your servers.
SSH is encrypted with Secure Sockets Layer (SSL), which makes it difficultfor these communications to be intercepted and read.
Note: Many of the commands in this article must be run on your localcomputer. The default commands listed are for the Linux command line orMacOS X Terminal. To make SSH connections from Windows®, you can use a clientsimilar to the free program, PuTTY.To generate keys, you can use a related program, PuTTYGen.
Using the Internet Protocol (IP) address and password for your cloud server, log in byrunning the following ssh
command with username@ipaddress
as the argument:
The system prompts you to enter the password for the account to which you’reconnecting.
If you rebuilt your cloud server, you might get the following message:
One of the security features of SSH is that when you log in to a cloudserver, the remote host has its own key that identifies it. When you tryto connect, your SSH client checks the server’s key against any keysthat it has saved from previous connections to that IP address. After yourebuild a cloud server, that remote host key changes, so your computerwarns you of possibly suspicious activity.
To ensure the security of your server, you canuse the web console in the Cloud Control Panel to verify your server’s new key.If you’re confident that you aren’t being spoofed, you can skip thatstep and delete the record of the old SSH host key as follows:
On your local computer, edit the SSH known_hosts
file and remove anylines that start with your cloud server’s IP address.
Note: Use the editor of your choice, such as nano
on Debian or theUbuntu operating systemor vi
on RPM or CENTOS servers. For simplicity, this article just uses nano
. If you prefer to use vi
,substitute vi
for nano
in the edit commands.For more on using nano
, seehttps://support.rackspace.com/how-to/modify-your-hosts-file/.
If you are not using Linux or MacOS X on your local computer, thelocation of the known_hosts file might differ. Refer to your OS forinformation about the file location. PuTTY on Windows gives you theoption to replace the saved host key.
You can secure SSH access to your cloud server against brute forcepassword attacks by using a public-private key pair. A public key is placed onthe server and a matching private key is placed on your local computer. If youconfigure SSH on your server to accept only connections using keys,then no one can log in by using just a password. Connecting clientsare required to use a private key that has a public key registered onthe server. For more on security, reviewLinux server security best practices.
Use the following steps to generate an SSH key pair:
Run the following command using your email address as a label.Substitute your email address for [email protected]
inthe command.
A message indicates that your public-private RSA key pair isbeing generated.
At the prompt, press Enter to use the default location or entera file in which to save the key and press Enter.
If you want the additional security of a password for the key pair,enter a passphraseand press Enter. If you don’t want to use a passwordwith the key pair, press Enter to continue without setting one.
Your key pair is generated, and the output looks similar to the following example:
Optionally, add your new key to the local ssh-agent file to enableSSH to find your key without the need to specify its location everytime that you connect:
You can use an SSH configuration shortcut instead of the ssh-agent fileby following the instructions in the Shortcut configuration sectionlater in this article.
To make it easy to add your key to new cloud servers that you create,upload the public key to your cloud account by following these steps:
Paste the contents of the id_rsa.pub file that you created intothe Public Key field. You can get the file contents by eitheropening the file in a text editor or by running the followingcommand:
If you want to add the key manually, instead of by using the Control Panel, reviewLinux server security best practicesand use the following command:
When you create a new cloud server, you can add a stored key to the newserver.
On the Create Server page, expand the Advanced Options section.
From the SSH Key menu, select your key from the list.
If you don’t see a stored key in the list, you can perform one of the following actions:
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You can’t use the Cloud Control Panel to add a public key to anexisting server. Follow these steps to add the key manually:
On your cloud server, create a directory named .ssh in the homefolder of the user that you connect to by using SSH.
Create or edit the authorized_keys file and add your public key tothe list of authorized keys by using the following command:
A key is all on one line, so ensure that the key isn’t broken byline breaks. You can have multiple keys in the authorized_keysfile, with one key per line.
Set the correct permissions on the key by using the following commands:
If you have any issues and need to fix permissions issues, run the following comand:
After you have added the public key to the authorized_keys, you can make an SSHconnection by using your key pair instead of the account password.
Use the following instructions to set up a connection shortcut by creating a~/.ssh/config file on your local computer and adding your server and keydetails to it.
Using a text editor, add the following text to the ~/.ssh/config file, changing thevalues to match your server information:
Each of the following entries describes a feature of the server:
After you set up the config file, connect to the server by usingthe following command with your shortcut name:
If you have trouble making a new connection after you restart theserver, use the following steps to help you resolve the issue:
The best way to troubleshoot SSH or SFTP login issues is to attempt tologin through SSH while logged into the Emergency Console and to watch the log,which typically includes the reason for a failure. If no reason is given,it could be a firewall issue. For RPM servers, run the following command to watch the log:
For Debian servers, run the following command to watch the log:
connection timeout
error, check the IP address thatyou used to ensure that it’s correct. You might also check theserver’s iptables to ensure that it isn’t blocking the port used by SSH.connection refused
error, you might be trying to useSSH with the wrong port. If you changed your server to listen to aport other than 22, use the -p
option with SSH to specifythe port.sshd
configuration to allow passwordconnections by setting PasswordAuthentication
to yes
. Restartthe server and try again. If you connect after these changes, thenthe issue is with the key and you must verify that the key is in theright place on the server.If all else fails, review your changes and restart the SSH daemon onthe server by running the following command:
If you get a message that the SSH service is unknown, run thecommand with sshd
as the service name instead.
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You generate an SSH key through macOS by using the Terminal application. Once you upload a valid public SSH key, the Triton Compute Service uses SmartLogin to copy the public key to any new SmartMachine you provision.
Joyent recommends RSA keys because the node-manta CLI programs work with RSA keys both locally and with the ssh agent. DSA keys will work only if the private key is on the same system as the CLI, and not password-protected.
Terminal is the terminal emulator which provides a text-based command line interface to the Unix shell of macOS.
To open the macOS Terminal, follow these steps:
The Terminal window opens with the commandline prompt displaying the name of your machine and your username.
An SSH key consists of a pair of files. One is the private key, which should never be shared with anyone. The other is the public key. The other file is a public key which allows you to log into the containers and VMs you provision. When you generate the 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 instances.
To generate SSH keys in macOS, follow these steps:
Enter the following command in the Terminal window.
This starts the key generation process. When you execute this command, the ssh-keygen
utility prompts you to indicate where to store the key.
Press the ENTER key to accept the default location. The ssh-keygen
utility prompts you for a passphrase.
You will need to enter the passphrase a second time to continue.
After you confirm the passphrase, the system generates the key pair.
Your private key is saved to the id_rsa
file in the .ssh
directory and is used to verify the public key you use belongs to the same Triton Compute Service account.
Never share your private key with anyone! |
---|
Your public key is saved to the id_rsa.pub
;file and is the key you upload to your Triton Compute Service account. You can save this key to the clipboard by running this:
Now you must import the copied SSH key to the portal.
You may see a password prompt like this:
This is because:
id_rsa
) does not match the public key stored with your Triton Compute Service account.Right in the portal, you can easily create Docker containers, infrastructure containers, and hardware virtual machines.
In order to use the Terminal to create instances, set up triton
and CloudAPI as well as the triton-docker
commandline tool.