[strongSwan] On what feature does ESN depend?

[Martin Willi]

Noel,

> I just tried to use esn (extended sequence numbers), but the responder got that error:
> 
> parsed CREATE_CHILD_SA request 2 [ N(IPCOMP_SUP) SA No KE TSi TSr ]
> received netlink error: No such file or directory (2)
> unable to add SAD entry with SPI cb1c9923

Can you confirm that this error is related to the use of ESN, and not
the use of IPComp? Have you tried to disable IPcomp? If it works
without, you are probably lacking IPComp support or the used compression
algorithm.

> On what kernel feature does esn depend? Is there an extra module for it?

ESN support was introduced with Linux 2.6.39, so unless your kernel has
a regression it should support it. ESN support at least on my kernel is
no option or module, and is always included in XFRM.

Regards
Martin