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Date:      Thu, 14 Jun 2018 09:02:04 +0100
From:      Frank Leonhardt <frank2@fjl.co.uk>
To:        freebsd-questions@freebsd.org
Subject:   Re: NIC locks up for no reason =?UTF-8?Q?=28=3F=29?=
Message-ID:  <723e3e676c32d6d9b18ffd189b2730a9@roundcube.fjl.org.uk>
In-Reply-To: <23524.1528853325@segfault.tristatelogic.com>
References:  <23524.1528853325@segfault.tristatelogic.com>

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On 2018-06-13 02:28, Ronald F. Guilmette wrote:
> I am experiencing a really rather odd problem, and could use some
> helpful advice.  I'm sure there is a good explanation for why this
> is happening, but at the moment I have no idea what it is.
> 
> More than a month ago, I got myself a shiny new VM on one of the
> many providers of such on the Internet.  I loaded up 11.1-RELEASE-p9,
> fiddled sshd so that it would run on a somewehat obscure unused port.
> 
> Anyway, after doing the above things, all was running well, and exactly
> as expected for some time thereafter.  (I have mostly just been using
> the box for some obscure research purposes.)
> 
> I never set up any kind of filewall on the thing because frankly,
> I was doing so little with the box I didn't think I'd need one.
> 
> Recently, I decided to install and run apache24, which I did.
> I configured that also to run on a non-standard port, since my
> intent was that the web stuff it would be serving up would only
> be stuff that I and perhaps a few close friends would look it.
> Apache started up just fine, and I was able to acces web content
> on the box via the non-standard port, from a system elsewhere on the
> Internet.  No problem.
> 
> Anyway, now it appears that the NIC on this VM system is effectively
> locking up from time to time, and I have no idea how to even begin
> to debug this problem.  This happened a few days ago, and I managed
> to get to a virtual console, I logged in as root, and then I rebooted
> FreeBSD on the VM and again, all was well... for awhile.
> 
> When this problem occurred before, it appeared that the (virtual) NIC
> of the VM was not accepting -any- packets from outside.
> 
> Now the NIC has locked up again.  Once again, from the outside it
> appears that it isn't responding to pings. or to traceroutes, or to
> ssh (on my non-standard port), or to attempts to telnet to the
> (non-standard) HTTP port I'm using.
> 
> Traceroutes -out- from the VM also get absolutely nowhere... not even
> one hop.  Pings rom the VM to its own (externally routable) IPv4
> address work fine.
> 
> I logged in again via the virtual console and once again, just like
> the last time this happened (a couple of days ago), I can see nothing
> obviously wrong.  There's plenty of free disk space, and top is showing
> the CPU as being >95% idle.
> 
> ifconfig output looks perfectly normal to me... the interface in
> question is listed as "UP".
> 
> Whet the devil could be wrong?
> 
> The relevant hosting company has assured me that they haven't been 
> doing
> anything new or special lately.
> 
> The Handbook says that (recent vintage) FreeBSD provides three 
> different
> flavors of firewalls.  Are any of these three enabled by default?  What
> about TCP Wrapper?  Is that enabled by default on an out-of-the-box
> install of 11.1-RELEASE?
> 
> What else could possibly explain a NIC periodically becoming totally
> unresponsive...  at least from the outside... apparently just because
> I had the audacity to install and run apache24?

I can't think of any method whereby Apache 2.4 could do anything to the 
network stack, or why installing it would do something similar via a 
dependency. It's always possible, but I suspect your virtual machine is 
the problem. The simulator is never as good as the real thing.

I've been making use of vultr.com's VMs for fun things, and I use 
11.1-STABLE on some, running Apache 2.4 and suchlike for months without 
a blip on those that I don't update and reboot. I've never had a problem 
and I'd be happy to recommend them for this kind of thing. At 
$2.50/month at some locations it's a small price to pay to keep 
experiments off my actual hardware.

Regards, Frank.




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