[Swan] Are libreswan and openswan interoperable ?

[jchludzinski]

Are libreswan and openswan interoperable ?

Whereas openswan is in the Raspbian repo, libreswan is not.

Tried building libreswan (3.25) under Raspbian and finally succeeded. I 
installed it but am having trouble with:  "Pluto listening for IKE on 
udp 500  [FAILED]"

The other box I need to communicate with is running libreswan (3.25), 
hence my problem.