Creating SSH shortcuts - CMU-18240/240-How-to GitHub Wiki

If you've already gone through the tutorials on Canvas, I'm sure you're already sick of typing out the entire SSH command. This page will help you stop doing that.

About SSH shortcuts

Inside of ~/.ssh/config (if you already have the file), we can define SSH "shortcuts" so instead of typing, say:

ssh -Y [email protected]

you can simply do

ssh cmu

Cool, right? Let's see how we can set that up.

Creating a .ssh folder

If you do not have a .ssh folder, then you'll have to make one:

mkdir ~/.ssh

If you need to check if you have said folder, then run

ls ~/.ssh

Modifying your SSH config

We will be adding the following block of text to our ~/.ssh/config. DO NOT SIMPLY COPY AND PASTE THIS BLOCK. See the notes below, as you have to customize it with favorite machine and your own Andrew ID.

Host cmu
Hostname unix.andrew.cmu.edu

Host ece
Hostname ece0XX.ece.local.cmu.edu

Host cmu ece
ForwardX11 yes
ForwardX11Trusted yes
User $ANDREWID

Where the XX in ece0XX... is a number between 00 and 31, inclusive. These are the available ECE machines you can SSH into, and $ANDREWID is just your Andrew ID. Note that you should not include the leading $.

So let's make these edits.

  1. Open your config by typing in your Unix terminal: vim ~/.ssh/config.
  2. At the top of your file, copy the previous textbox's contents and paste. You may have trouble pasting into Vim, so if it comes down to it you should probably just type it in manually. Don't whine, the effort here will save you countless seconds typing in an SSH hostname.
  3. In the previous step, don't forget to replace XX with a number between 00 and 31, and also $ANDREWID with your own!
  4. Save and quit.

You should now be able to use your SSH shortcuts. Note that these shortcuts already have X11 forwarding enabled, so no need to use the -Y flag.

Checking if it works

ssh cmu

Will allow you to SSH into the Unix machines. Note that these are not the same as the ECE machines! They do not have the tools you need to compile, simulate, and synthesize your code in 240!

ssh ece

Will actually SSH into the ECE machines. Note that these machines are only available on the CMU domain, so if you are off campus, you must VPN in.

Also note that the ECE machines are shared machines, so you may want to create aliases to a few of the machines if one us busy.

Resolving permission errors on .ssh/config

You may run into a problem where trying to SSH gives an error like

Bad owner or permissions on...

To solve this, you can try taking ownership of the file:

sudo chown $USER ~/.ssh/config

(where $USER is your username in your terminal)

Or, you can give yourself read/write permissions:

chmod 600 ~/.ssh/config

Reference: https://serverfault.com/questions/253313/ssh-returns-bad-owner-or-permissions-on-ssh-config

Next step

Finally, the last step for setting up your environment is resolving your paths on the ECE machines.

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