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Date:      Sun, 1 Feb 1998 22:01:27 -0500 (EST)
From:      Thomas David Rivers <rivers@dignus.com>
To:        freebsd-hackers@freefall.FreeBSD.org
Subject:   natd "strangness"..
Message-ID:  <199802020301.WAA02139@lakes.dignus.com>

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Ok -

 I just want to mention a natd issue I seem to have tripped over; 
perhaps it's corrected in a newer version.

 First - this is a 2.2.5-RELEASE setup - everything's just straight
2.2.5-RELEASE>

 Here's the situation:
                                                                 _________
	+----------+                  +--------+                /         \
        |  lakes   |---- (ether) ---- | ponds  |=== (modem) == |  Internet |
	+----------+                  +--------+                \         /
                                                                 ---------

 lakes is 10.0.0.3 (ether net)
 ponds is 10.0.0.1 (ether net)
 ponds is 166.82.100.202 (Slip to my ISP.)

So, as you can imagine - I'm running natd on 'ponds' to be able to
connect from the internal network to the internet-at-large.

 Now, if I start up netscape on 'ponds' (with the DISPLAY pointing
back to 'lakes') - things work fine, since 'ponds' is on the internet.

 But - if I start up netscape on 'lakes' - things _mostly_ work fine.
It seems, however, that large requests can get bogged down, or not
get through at all (as if some packet reconstruction was messing up
natd.)

 I've done this by running netscape on both machines, pointing to the
same sight.  The netscape running on 'ponds' will get to the site just
fine, while the one on 'lakes' will bail out after some time indicating
the server wasn't working...  this is especially true for something like,
an audio stream for example.

 The symptom is that a large "something" (graphics, audio, etc....)
takes much longer, or is even impossible to receive, on 'lakes' - while 
it works just fine on 'ponds'... at exactly the same time.

 About the only thing I can imagine going on here is natd...  And,
I'm guessing it has to do with piggy-back'd ACKs or perhaps some other
packet issues...

 Any thoughts?  Does anyone have suggestions as to what I could check?

 Just for info - here's my rc.firewall rules.  They are someone complicated,
the rules for sl1 are to handle a situation where I'm connected to
work (which uses it's own internal IP numbers).  The rule via sl0
at the end is to handle connecting to the "internet-at-large".

 Could there be some interaction(s) here?


        ipfw -f flush
        ipfw -f add 10 divert 32001 ip from any to 192.42.243.0/24 via sl1
	ipfw -f add 11 divert 32001 ip from 192.42.243.0/24 to any via sl1
	ipfw -f add 12 divert 32001 ip from 149.173.0.0/16 to any via sl1
	ipfw -f add 13 divert 32001 ip from any to 149.173.0.0/16 via sl1
	ipfw -f add 14 divert 32001 ip from 10.23.0.0/16 to any via sl1
	ipfw -f add 15 divert 32001 ip from any to 10.23.0.0/16 via sl1
	ipfw -f add 16 divert 32001 ip from 10.253.0.0/16 to any via sl1
	ipfw -f add 17 divert 32001 ip from any to 10.253.0.0/16 via sl1
        ipfw -f add 20 divert 32000 ip from any to any via sl0
        ipfw -f add pass ip from any to any



	  - Thanks -
	- Dave Rivers -



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