Re: [PLUG] tcpdump shows network traffic when no interface is connected

[Walt Mankowski via plug <plug@lists.phillylinux.org>]

On Mon, Jun 05, 2023 at 09:15:04AM -0400, Rich Freeman via plug wrote:
> On Mon, Jun 5, 2023 at 9:03 AM Walt Mankowski via plug
> <plug@lists.phillylinux.org> wrote:
> > That said, while I'm no expert at reading these dumps either, modern
> > OSs are designed with the assumption that they're online all the time,
> > and the sites I saw all looked routine to me. For instance, it looks
> > like it was hitting your distro's repos to check for security updates.
> >
> 
> Plus, how does an application even know if it is online?  Or even an
> OS?  With the myriad of network tunneling options out there, about the
> only way you could reliably tell if you're able to reach a host is to
> just try to do it.  There are a gazillion ways for a packet to get
> from point A to point B and Linux supports just about all of them,
> including solutions via userspace, serialized solutions, or even
> AX.25.

Right, and apps will generally assume that it's a temporary outage
(e.g. Comcast is down) and will keep trying until you're back online
and whatever it's trying to do works.

Walt
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