Thinking about UDP and tunneling

Randall Stewart rrs at
Wed Nov 19 07:00:30 PST 2008

Dear All:

I have been contemplating UDP and tunneling. One of the
things that is a nice feature in MacOS is the ability of
a kernel module/extension to open a kernel level socket
and have the mbuf chain that arrives for that port be passed
in via a function.

We use this in our MacOS version of the SCTP stack to do the
UDP de-tunneling of SCTP packets. This is becoming a more and
more common thing i.e. having transport protocols like SCTP and DCCP
be tunneled over UDP to get by NAT's.... this actually sucks that
this is necessary .. but it is what it is....

So, I am contemplating adding a similar sort of feature... basically
provide an interface in UDP that a consumer (such as SCTP or DCCP) could
use to "bind" a port and get UDP packets directly.

What do you all think of the idea?

That also reminds me.. who owns the ipfw code.. we actually
have SCTP nat support that Jason But has done that we need to
get in...

I would be more than glad to shepherd this in if the owner
of the code does not have the time...

Randall Stewart
803-317-4952 (cell)

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