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Date:      Thu, 1 Nov 2001 06:31:04 -0600
From:      mikea <mikea@mikea.ath.cx>
To:        Graham Menhennitt <gmenhennitt@optushome.com.au>
Cc:        freebsd-stable@FreeBSD.ORG
Subject:   Re: network interface dies randomly - ifconfig down then up fixes
Message-ID:  <20011101063104.C9373@mikea.ath.cx>
In-Reply-To: <5.1.0.14.0.20011101223313.00a23670@mail.mckinn1.vic.optushome.com.au>; from gmenhennitt@optushome.com.au on Thu, Nov 01, 2001 at 10:39:33PM %2B1100
References:  <5.1.0.14.0.20011101223313.00a23670@mail.mckinn1.vic.optushome.com.au>

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On Thu, Nov 01, 2001 at 10:39:33PM +1100, Graham Menhennitt wrote:
> I have a Arris Cornerstone CM200 cable modem connected to my FreeBSD stable 
> (cvsupped last week) box via UTP into a NE2000 compatible ISA Ethernet 
> adaptor. The connection randomly dies. I can send pings out of it and see 
> the Activity LED flash on the modem but the FreeBSD box never sees any 
> replies. Doing "ifconfig ed1 down" followed by "ifconfig ed1 up" fixes it. 
> It's been happening for about the last two weeks (so it happened before the 
> most recent cvsup also).

It could be your cable provider doing things on their network.
I have found that they are fond of making changes during prime
time daylight, rather than in the wee hours, and most of their
changes require me to reset my cablemodem (power cycle). 

If your /var/log/messages shows things like your upstream
gateway MAC address changing (I run arpwatch, so I see that),
then that has a high probability of being the problem. 

If not, then you may need to run tcpdump continuously on that
interface to catch the ACK and SYN packets. I do that, too, 
so that I can trace attacks, but I do computer security for
a living and hence am a professional paranoid.

-- 
Mike Andrews
mikea@mikea.ath.cx
Tired old sysadmin since 1964

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