Currently, in Ubuntu, there is only a NetworkManager-plugin for strongSwan only in combination with IKEv2. There exists an alternative plugin, which supports the management of IPsec-connections which require IKEv1. This plugin did not make it into the official Ubuntu-repository yet – a feature-request for including the network-manager-libreswan-plugin as an installable package is pending.

The following steps will guide you to get the recent version of the plugin to work in Ubuntu, in this case, 17.10:

apt-get install intltool libnl-3-dev libgtk-3-dev libnma-dev libsecret-1-dev libnm-gtk-dev libnm-glib-vpn-dev git 

git clone -b 1.2.6 https://git.gnome.org/browse/network-manager-libreswan

cd network-manager-libreswan

./autogen.sh

make && make install 

mv /usr/local/etc/NetworkManager/VPN/nm-libreswan-service.name /etc/NetworkManager/VPN/

If this information is not up-to-date anymore or not working in your specific case, please just leave me a comment.