[CentOS] How to create a tun-device with CentOS packages only?

Hello List,

I've got a somewhat weird question. Let me tell you what my intent is first: We're running a set of Dell boxes with CentOS 4. Some of them use OpenVPN. As we need to monitor the system status of these boxes, we use the Dell supplied OMSA package. As it turns out, OMSA totally breaks if you've got one or more tun devices configured. AFAICT Dell denies support with that issue, because OpenVPN is a third-party add-on. Now instead of discussing with Dell for hours, I'd like to reproduce the issue without OpenVPN which brings me to my question:

How can I create a tun device without using any add on packages using only software contained in CentOS?

Regards, Andreas