I have a small VPN set-up. The client in question is a Raspberry Pi running
xl2tpd to run as IPsec/L2TP. I made a configuration mistake on the client where I set
pfs=yes (for perfect forward security) even though the server has it set to
no. I fixed that, and now all is well, but the symptoms were curious and I wonder if someone can explain what I saw:
Namely, with the wrong configuration, the client was establishing a valid IPsec/L2TP connection, which could be verified on the server and worked on the client, BUT the connection consistently dropped at 2.1 minutes. I get that the configuration was broken and it should drop, but I'm wondering if there's a good explanation for why the connection could be established in the first place? It seems like this should have never connected rather than connecting for a while and then dropping.