Thinking about UDP and tunneling

Max Laier max at
Wed Nov 19 07:45:29 PST 2008

On Wednesday 19 November 2008 16:00:27 Randall Stewart wrote:
> 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?

What is wrong with the existing socket(9) API?

> 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...

"Depends ..." ... for ipfw2 core you might be looking for luigi@, for the 
libalias stuff: piso@ did the kernel inclusion more or less recently ... other 
than that:

svn log -qr HEAD:\{2006-01-01\} | grep ^r | cut -d"|" -f2 | sort | \
   uniq -c | sort

in sys/netinet/libalias gives a list of people who touched that code recently 
(for some definition of recently).

I'd be happy to take a look, too ... though I might need some time for a 
proper review.

In general, you touch it you bought it!

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