WSL2 Ubuntu: How to start ssh-agent and add ssh key automatically on each terminal start up

Question

I'm using WSL2, on Terminal, with Ubuntu installed. I have added the following to my .bashrc:

# Start ssh-agent
# check if ssh-agent is already running
if [ -z "$SSH_AUTH_SOCK" ]; then
     #start ssh-agent
    eval "$(ssh-agent -s)"
fi


# Ask for ssh-add
read -p "Do you want to add your SSH public key? (y/n) " response

if [ "$response" = "y" ]; then
  ssh-add ~/id_rsa
  ssh-add -l
elif [ "$response" = "n" ]; then
  echo "No identity on terminal session"
else
  echo "Invalid response"
fi

With the idea that every time I open a new terminal, it will ask for a prompt if an identity is needed and proceed to start ssh-agent and add the key if yes. At first, it appears as if the script work and it'll show the agent's PID, along with a prompt for my ssh password and I'm able to see the ssh-agent when i do top. However, it did not actually initialize ssh-agent nor add the key, despite seeing the output of these commands. I even did ssh-add -l and it'll output: The agent has no identities.

How do I go about making this work? This has to be a WSL issue..

Answer 1

Hum... you try to load ~/id_rsa. Usually, keys are in the ~/.ssh folder. AFAIR ssh is also very picky with file and folder permissions. If a key is in a directory that ssh thinks not secured enough, it won't use it.

If your key is really in ~, move it (and the corresponding .pub file) into the ~/.ssh folder. Make sure you own the files and the ~/.ssh has 0700 mode, ~/.ssh/id_rsa should have 0600 mode. See chmod(1) if you don't know how to do that.

Also, there's no need to give a filename to ssh-add. As per the man-page:

ssh-add adds private key identities to the authentication agent, ssh-agent(1). When run without arguments, it adds the files ~/.ssh/id_rsa, ~/.ssh/id_ecdsa, ~/.ssh/id_ecdsa_sk, ~/.ssh/id_ed25519, ~/.ssh/id_ed25519_sk, and ~/.ssh/id_dsa. After loading a private key, ...

in short :

• make sure your key files are in ~/.ssh folder,
• in your .bashrc file just use ssh-add.

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A quick note: Having questions in .bashrc is not necessarily a good thing. There exist situations (but maybe not in WSL) when .bashrc is loaded in non-interactive situations. If you really want to ask questions, read answers, protect the whole thing with a test on PS1

if test "$PS1"; then
  if [ -z "$SSH_AUTH_SOCK" ]; then
    #start ssh-agent
    eval "$(ssh-agent -s)"
  fi

  # Ask for ssh-add
  read -p "Do you want to add your SSH public key? (y/n) " response

  # and so on...
fi

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EDIT NOTE:

I removed technical text that was not mine, but was added by someone else. Style, grammar, typos etc... corrections are always welcome. That someone adds his/her thoughts to my answer is not appreciated. thank you.