n.b. over email Tobias, the developer of StrongSwan said to me:
"We have absolutely no intentions of ever adding support for L2TP (or IKEv1 for that matter) to our NM plugin. So I doubt there will be any traction on this issue (unless Canonical tracks back and readds the removed Openswan/Libreswan stuff).
You should perhaps consider using a more modern VPN protocol, for instance, IKEv2. <redacted> appliances (at least some of them) support that too."
However it is not possible to create "on demand"/random source IPSec VPNs using IKEv2 on the appliances that I'm using, so I'm back tot he beginning again.
n.b. over email Tobias, the developer of StrongSwan said to me:
"We have absolutely no intentions of ever adding support for L2TP (or IKEv1 for that matter) to our NM plugin. So I doubt there will be any traction on this issue (unless Canonical tracks back and readds the removed Openswan/Libreswan stuff).
You should perhaps consider using a more modern VPN protocol, for instance, IKEv2. <redacted> appliances (at least some of them) support that too."
However it is not possible to create "on demand"/random source IPSec VPNs using IKEv2 on the appliances that I'm using, so I'm back tot he beginning again.