charon-cmd is a simple IKE client (IPsec VPN client). It is available in most linux distributions and is very simple to install and configure.

# Install `charon-cmd` and `libcharon-extra-plugins`

If you are using debian, run:

    $ sudo apt-get install charon-cmd libcharon-extra-plugins


# Download the certificate for the CA from the server (the ca.crt file)

# Type:

    $ sudo charon-cmd --cert /path/to/the/cert/ca.crt --host example.com --identity username


You must replace `/path/to/the/cert/ca.crt` with the path to the ca.crt file, `example.com` with the actual hostname, and `username` with the actual username.

When asked, type in your user's password and press <Enter>.

To disconnect from the server, press <Ctrl-c>.