Does OpenVPN really use IPSec-over-UDP ?

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Does OpenVPN really use IPSec-over-UDP ?

Post by alexeypolo » Wed Jun 01, 2016 11:25 am

I am bringing up a VPN server node, which needs to support both IPSec and TLS/SSL vpns. The IPSec traffic is going to be accelerated with DPDK. Since DPDK works at L2/3, it cannot accelerate higher level traffic (at least not at protocol level). Until today I thought that OpenVPN has no relation to IPSec and a s a result, I will be only be able to accelerate OpenVPN crypto operations (if any).

However, I came across this "Why OpenVPN" documentation: ... envpn.html
It says that OpenVPN over UDP actually uses IPSec ESP tunnel !!!
Is this true or is it a typo?
I looked for ipsec in the source repo on github, but didn't find anything that would suggest that IPSec tunnel is actually used.

Appreciate your help!

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Re: Does OpenVPN really use IPSec-over-UDP ?

Post by FalconTent » Wed Jun 01, 2016 12:47 pm

alexeypolo wrote:It says that OpenVPN over UDP actually uses IPSec ESP tunnel !!!
It actually says:
OpenVPN's security model is based on using SSL/TLS for session authentication and the IPSec ESP protocol for secure tunnel transport over UDP
which I believe means .. the same Idea but not the same protocol.

OpenVPN protocol is not compatible with IPSec protocol .. nor vice-versa ..

Questions regarding IPSec come up from time to time possibly because some of the documentation has not been suitably revised .. due to time constraints of the developers.

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