SSH (the Secure SHell) is a protocol for allowing people to access a computer over the Internet and run programs on it as if they were physically present.
| If you are running | Then you should use |
|---|---|
| Linux | open a terminal and use the built-in ssh command |
| MacOS | open the Terminal app, then use the built-in ssh command |
| Windows 10 | enable it once; then open the PowerShell app and use the ssh command |
| Haiku | open a terminal and use the built-in ssh command |
| FreeBSD | open a terminal and use the built-in ssh command |
| OpenBSD | open a terminal and use the built-in ssh command |
| Irix | open a terminal and use the built-in ssh command |
Typing passwords is both less secure (key-sniffers, typos, typing wrong passwords, etc) and more tedious than using a private key.
You’ll place a file on your computer and a file on the remote computer. They are matched, and each provides half of the work needed to do a job. When you log in, the remote computer will do half the work with its file, then send that to your computer to do the other half, then send it back, thus allowing both computers to be confident the other computer is who it says it is1.
The following commands should work on any system with SSH installed, with appropriate changes to username@the.server.edu;2
When prompted for a passphrase by ssh-keygen, just press enter without typing anything.
ssh-copy-id -i ~/.ssh/id_rsa.pub username@the.server.eduWhen prompted for a passphrase by ssh-copy-id, use your UVA CS account password.
You’ll need to do the ssh-keygen once per client machine you use (e.g., you laptop)
The following copies files to the CS SSH portal, then compiles and runs them on the server and displays the output on your laptop.
Open with ssh username@the.server.edu
Close with exit or Ctrl+D
ssh mst3k@portal.cs.virginia.edu
ssh username@the.server.edu command arg1 arg2 ...
–or–
ssh username@the.server.edu "commands to execute"
ssh mst3k@portal.cs.virginia.edu ls -l
ssh mst3k@portal.cs.virginia.edu "cd /tmp; ls"
scp file file2 file3 ... user@the.server.edu:path/to/destination/
scp testfile.c mst3k@portal.cs.virginia.edu:code/demo1/
Note that scp will not create directories, but ssh can:
ssh mst3k@portal.cs.virginia.edu mkdir -p code/demo1/
scp user@the.server.edu:path/to/source/filename path/to/destination/
(use ./ for put it where I am
)
scp mst3k@portal.cs.virginia.edu:code/demo1/testfile.c ./
This is a gross over-simplification, but gets the core idea across. We’ll see what’s really going on when we discuss digital certificates in CSO2↩︎
If on Windows, you also may need to use \ instead of / (whether you do or not depends on which command line tool you use).
There is a slight chance that ~/.ssh will not already exist. In that case ssh-keygen will fail; if you see such a failure you can fix it by running
and then re-run the above commands↩︎