Re: IPIP Tunnelling.

Olaf Titz (
Tue, 05 Aug 1997 00:28:48 +0200

> Another thing I'd like to do is add IPIP compression to the tunnel
> driver. What's the best way to go about it? Is there an alternative
> protocol to IPPROTO_IPIP which indicates that the encapsulated
> packet is compressed, or should I just compress the original packet
> before packaging it and rely on the IPIP decapsulator to notice that
> it's not a valid IP packet, but is in fact compressed data? If I'm

IPIP (protocol 4) requires that the contents of the packet form a
valid IP header which satisfies certain properties wrt. the packet
header. Routers may look at the packet contents. See RFC 2003. You
should use another protocol number.

> doing such things, I suppose I ought to add hooks for encryption,

I have already done this for encryption, see
<URL:>. Adding hooks for
compression was a thing I thought about for future development. :-)
(Btw., I'm using UDP instead of an own IP protocol number, for various