Start ssh-agent on login

Old question, but I did come across a similar situation. Don't think the above answer fully achieves what is needed. The missing piece is keychain; install it if it isn't already.

sudo apt-get install keychain

Then add the following line to your ~/.bashrc

eval $(keychain --eval id_rsa)

This will start the ssh-agent if it isn't running, connect to it if it is, load the ssh-agent environment variables into your shell, and load your ssh key.

Change id_rsa to whichever private key in ~/.ssh you want to load.

Some useful options for keychain:

• -q Quiet mode
• --noask Don't ask for the password upon start, but on demand when ssh key is actually used.

Reference

https://unix.stackexchange.com/questions/90853/how-can-i-run-ssh-add-automatically-without-password-prompt

On Arch Linux, the following works really great (should work on all systemd-based distros):

Create a systemd user service, by putting the following to ~/.config/systemd/user/ssh-agent.service:

[Unit]
Description=SSH key agent

[Service]
Type=simple
Environment=SSH_AUTH_SOCK=%t/ssh-agent.socket
ExecStart=/usr/bin/ssh-agent -D -a $SSH_AUTH_SOCK

[Install]
WantedBy=default.target

Setup shell to have an environment variable for the socket (.bash_profile, .zshrc, ...):

export SSH_AUTH_SOCK="$XDG_RUNTIME_DIR/ssh-agent.socket"

Enable the service, so it'll be started automatically on login, and start it:

systemctl --user enable ssh-agent
systemctl --user start ssh-agent

Add the following configuration setting to your local ssh config file ~/.ssh/config (this works since SSH 7.2):

AddKeysToAgent  yes

This will instruct the ssh client to always add the key to a running agent, so there's no need to ssh-add it beforehand.

Please go through this article. You may find this very useful:

https://web.archive.org/web/20210506080335/https://mah.everybody.org/docs/ssh

Just in case the above link vanishes some day, I am capturing the main piece of the solution below:

This solution from Joseph M. Reagle by way of Daniel Starin:

Add this following to your .bash_profile

SSH_ENV="$HOME/.ssh/agent-environment"

function start_agent {
    echo "Initialising new SSH agent..."
    /usr/bin/ssh-agent | sed 's/^echo/#echo/' > "${SSH_ENV}"
    echo succeeded
    chmod 600 "${SSH_ENV}"
    . "${SSH_ENV}" > /dev/null
    /usr/bin/ssh-add;
}

# Source SSH settings, if applicable

if [ -f "${SSH_ENV}" ]; then
    . "${SSH_ENV}" > /dev/null
    #ps ${SSH_AGENT_PID} doesn't work under cywgin
    ps -ef | grep ${SSH_AGENT_PID} | grep ssh-agent$ > /dev/null || {
        start_agent;
    }
else
    start_agent;
fi

This version is especially nice since it will see if you've already started ssh-agent and, if it can't find it, will start it up and store the settings so that they'll be usable the next time you start up a shell.

Add this to your ~/.bashrc, then logout and back in to take effect.

if [ ! -S ~/.ssh/ssh_auth_sock ]; then
  eval `ssh-agent`
  ln -sf "$SSH_AUTH_SOCK" ~/.ssh/ssh_auth_sock
fi
export SSH_AUTH_SOCK=~/.ssh/ssh_auth_sock
ssh-add -l > /dev/null || ssh-add

This should only prompt for a password the first time you login after each reboot. It will keep reusing the same ssh-agent as long as it stays running.