[strongSwan] Strongswan: centos 3.9 kernel version 2.4.21.47

[Martin Willi]

> kernel version 2.4.21.47

Linux 2.4 is very old, and in vanilla it does not even have an IPsec
stack. There have been patches for both a backport of the 2.6
Netkey/XFRM stack and the 2.4 KLIPS stack, not sure though if you can
find them these days?

While it might be possible to get things running on such a kernel, I
highly recommend to switch to a newer OS. We certainly can't help you
much with any issues.

Regards
Martin