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Date:      Tue, 15 Oct 1996 12:54:36 -0700
From:      Julian Elischer <julian@whistle.com>
To:        Brian Candler <B.Candler@pobox.com>
Cc:        bugs@FreeBSD.org, nato-ws@ripe.net, t12@psg.com
Subject:   Re: IP bugs in FreeBSD 2.1.5
Message-ID:  <3263EBFC.1CFBAE39@whistle.com>
References:  <199610151340.OAA00334@gazebo.candler.demon.co.uk>

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Brian Candler wrote:
> 
> Dear FreeBSD team,
> 
> I have just returned from a NATO-sponsored Advanced Networking Course held
> in St Petersburg, Russia, where I was the chief instructor.
> 
> For our PC-based practical sessions we used FreeBSD 2.1.5.
>
NEAT!

I hope each participant got a FreeBSD cdrom as part of the 
course materials! :)

> We uncovered a
> number of bugs in the TCP/IP code, which I would like to report in the hope
> they can be fixed in some future release.

certainly..
Have you looked at any of these problems with 2.2?

> 
> 1. On several occasions we found that although a default route appeared to
> be in the kernel forwarding table (as shown by netstat -nr), it did
> not work. However simply by deleting and reinserting the exact same
> default route, it then worked fine. I'm afraid I can't give you
> a set of circumstances which can cause this problem to be
> reproduced.
> 
possibly another route preceeded it in some way 
I can imagine such a case but can't quite put my finger on  a
mechanism.

> 2. When you set up a ppp link, you cannot ping your own IP number
> locally. (This is using kernel-based ppp, with pppd to set up the
> link)

Under -current pinging the local end address certainly works.. 
even if the link is not up. of course pinging the remote end fails :)


 
> 3. When you use ipalias to set up multiple IP addresses for an
> ethernet card, you cannot ping those additional IP numbers locally.

hmmmmm interesting... they are logically identical to the original.
address, it certainly works for me under -current.


> 
> 4. If you 'ifconfig down' an interface, then set up a default route
> via another interface, you still cannot ping the range of IP numbers
> which the original interface covered - presumably the kernel still
> tries to send them via the (downed) interface.

I think I've seen related things
sometimes the kernel keeps hold of rtentry structs with outdated
information, even though they are not in teh table any more..
this is because the protocol PCBs 'cache' them and
there is no way to flush cached rtentry's.
It's on my "look at this some more" list

> 
> 5. On one occasion the kernel forwarding table had a bad entry (I
> think a "link #1" type entry) which could not be removed, apart from
> by rebooting the machine.
> 

sorry, no idea



> I am unlikely to have time to look at the source code myself I'm
> afraid, but I hope you don't mind me submitting the notes above. Apart
> from these points, and "vi" dumping core a few times, FreeBSD was
> stable for the whole week we were using it.
> 
without such feedback we'd have a much harder time fixing the system!

> Thanks in advance for your attention,
> 
> Brian Candler <B.Candler@pobox.com>



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