*BSD News Article 93393


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From: nsayer@quack.kfu.com (Nick Sayer)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: IPDIVERT and fragmentation
Date: 7 Apr 1997 19:02:22 GMT
Organization: The Duck Pond public unix - http://www.kfu.com/
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I am thinking about implementing a virtual private network
scheme for FreeBSD using ipfw and a divert channel.

VPNs mean that you encrypt the traffic going between LAN A and
LAN B as it passes over the Internet.

My implementation is going to use UDP encapsulation, so the
packets will get a tiny bit bigger as they travel over the
Internet. The question is this:

What happens if I had a packet that is too large for the MTU of
the underlying medium to the 'out' side of a divert socket?
Will the IP layer _after_ divert fragment the packet?

On the opposite side of the coin, what happens if a fragmented packet
comes in from a network interface and is destined for a divert
socket? Can I expect that the fragments have been collected
and the packet reassembled before being given to me or must I assemble
them myself?

advTHANKSance

-- 
Nick Sayer <nsayer@quack.kfu.com>  | "The judgement of history
N6QQQ @ N0ARY.#NORCAL.CA.USA.NOAM  | depends on who writes it."
+1 408 249 9630, log in as 'guest' |      -- Richard M. Nixon
URL: http://www.kfu.com/~nsayer/   | 	(1913-1994 R.I.P.)