ssh configuration

You should be in your home directory. The cd command without any argument will bring you home. The pwd command will tell you the name of that directory. Here is how it looks for me.

$ cd
$ pwd
/home/bon
$

In that directory there should be a subdirectory called .ssh. You can check that it's there using the ls command but the ls command does not show files or directories that start with a dot by default so we will ask for it explicitly like this

$ ls -d .ssh
.ssh
$

The -d option means show me the directory, not its contents.

If it shows you nothing like this

$ ls -d .ssh
$

you will need to make the directory like this

$ mkdir .ssh
$

You should now edit a file called .ssh/config to contain the lines in the following code block. Perhaps the file is there already, in which case you should put these lines at the top of the file.

Host git.auc-computing.nl
  IdentityFile ~/.ssh/id_ed25519
  User forgejo
  AddKeysToAgent yes
  IdentitiesOnly yes
  ServerAliveCountMax 30
  ServerAliveInterval 5
  StrictHostKeyChecking accept-new
  ControlMaster auto
  ControlPersist yes
  ControlPath ~/.ssh/control/%r@%h:%p

The section for advprog is for our Linux server. Breanndán's group is using it but Lorenzo's is not. You can omit this section if you don't need it.

If you already have a .ssh/config file from a previous course that you no longer need, you can just rename the file to something else before makng a new one, as follows.

$ mv .ssh/config .ssh/config.1

If you already have a .ssh/config that you still need and you want to combine the configuration with that for the AdvProg course, you should probably ask Breanndán how to do that.

When you have saved the file, make sure it is indeed called config. Some editors on Windows make the name config.txt.

Here is how to check:

$ ls .ssh
config
$

This is good. (You may also see othe files there.)

$ ls .ssh
config.txt
$

If you see the above then rename it.

mv .ssh/config.txt .ssh/config

If you do not already have a key pair, you can generate it as follows

$ ssh-keygen -t ed25519

You should now see a private key ~/.ssh/id_ed25519 and a public key ~/.ssh/id_ed25519.pub

In order to allow your git to access the Forgejo server you need to visit it in your browser and put the contents of your public key there. You can check that you have done this successfully using the following command. You may be asked for the password for your private key before it gives you output. If you do get output such as this you are ready to use git with the Forgejo server to clone, push and pull.

$ ssh -T forgejo@git.auc-computing.nl
Hi there, bon! You've successfully authenticated with the key named forgejo, but Forgejo does not provide shell access.
If this is unexpected, please log in with password and setup Forgejo under another user.
$

(Note that my id is bon and my key is called forgejo.)

If you do not get output like this but your are asked for a password for forgejo@git.auc-computing.nl then something has gone wrong and you should check your configuration.