What is SSH?
The acronym 'SSH' stands for 'Secure Shell', and a 'Shell' is simply another word to describe a command-line interface on a computer. So, getting an 'SSH' connection to your server is just a way to get access to your server's command-line interface.The Linux command-line interface is well-known for being extremely powerful and effecient. Once you have access to the command-line of your Linux server here at Vivio, you will be able to edit files, configure services, update settings, and other server-related tasks using the most direct and effecient methods possible.
This article will cover the basics of how to access your Linux server's command-line interface from your Windows desktop using freely available tools. All you need is your Windows desktop, an active Linux server here at Vivio, and an Internet connection.
Why would you use SSH?
Becoming comfortable with using SSH may seem daunting, but it's actually pretty simple once you get used to it. Using the command-line enables you to perform many large, complex tasks easier then you would be able to using a graphical interface. What's more, the Linux command-line interface takes far less resources on your server than a graphical interface does - this saves you money because you're using less resources for a graphical interface and more resources can go to your applications.
Introducing PUTTY
PUTTY is a freely available (free to download and use for any purpose) program that enables Windows users to access their Vivio Linux Servers over SSH. To download PUTTY, simply visit the following URL:
http://www.chiark.greenend.org.uk/~sgtatham/putty/download.html
You'll see a screen like the following:
Go ahead and download the Windows Installer link as indicated above. Once the file is downloaded, go ahead and run it to install PUTTY on your machine. The default options it gives you are perfectly fine for most purposes.
Once you've installed PUTTY, you should see a new icon on your desktop that looks like this:
When you signed up for your Vivio Hosting Account, you should have received a 'welcome' email which gave you access to your SSH login details. Be sure you have those login details ready at this point.
When you launch PUTTY, you'll be presented with the following screen:
Note the 'Host Name' and 'Port' values in the screen shot above (highlighted in red). You will need to retrieve those values from your SSH login details that Vivio gave you access to when you signed up for an account with us.
Enter in your server name and port number, and hit the 'Open' button at the bottom.
The first time you connect to your server, PUTTY will prompt you to see if you want to import a new 'Key'. This is normal and part of the process of securing your connection. The screen will look a little like this:
You will always get a prompt like this the first time you connect to a new machine. If you get this prompt when connecting to a machine that you talk to regularly, watch out! Be sure your trust the key before you accept it - otherwise your connection may not be safe. However, since this is our first time connecting to our Vivio Linux Server, you can go ahead and hit the "Yes" button to accept the key.
PUTTY will then prompt you for the username that you want to log in as. This should also be provided to you from the information from the 'welcome' email. The screen will look something like this:
After you've provided your username, PUTTY will then prompt you for your password:
Again, use the password that was provided to you by the Vivio 'welcome' email. You should then log in successfully and be givin the Linux command-line prompt.
Useful Commands
The Linux command-line is a powerful tool for system administrators. Here are a fw of Vivio's favorite commands to get you started on using the Linux command-line interface to manage your servers:
- top
'top' is a processes monitor and can show you want programs on your server are taking up the most server resources, how much memory is being used, and how your separate CPU cores are being utilized. It is extremely helpful for diagnosing what's going on inside your server.
Example: 'top -c' - shows the processes and the full command that launched them - free
Similar to 'top', but much more specific, 'free' simply shows how much memory is free and available on a system.
Example: 'free -h' - shows memory usage in human readable format - find
'find' is an extremely powerful search tool that can locate files based on name, last modified date, and a whole host of other options.
Example: 'find / -name myfile*' - searches for a file whos name beings with 'myfile' - df
'df' is useful for checking disk space usage.
Example: 'df -h' - shows partition usage in human readable format - shutdown
The 'shutdown' command can schedule a shutdown process, and when paired with the -r option, can be used to schedule a reboot.
Example: 'shutdown -r now' - reboots a server right now - exit
Typing 'exit' is the proper way to end a terminal session. Type this when you're done!