Re: can't reach internet.

[George N. White III]

On Mon, Jun 13, 2022 at 4:45 PM home user  wrote:
> On 6/13/22 4:30 AM, George N. White III wrote:
> > You will find it well worth the effort to learn some basics of network
> > troubleshooting:
> > A beginner's guide to network troubleshooting in Linux | Enable Sysadmin
> > (redhat.com)
> > <
>
> https://www.redhat.com/sysadmin/beginners-guide-network-troubleshooting-linu...
> >
>
> I gave it a first pass.  For me, it seemed to be overkill; much was over
> my head.  But I'll give it a second-pass reading later.
> > The only speed test I've ever seen seemed very "snoopy" and intrusive
> > the last time I accessed it.  That was some time ago, I don't recall
> > when.  I do recall Firefox and/or NoScript not liking the site.  I've
> > never seen any hint of a speed test being offered by my ISP
> > (comcast/xfinity), though I log into that company's site at least
>
> once
> > per month.  Status site for comcast: see my reply to Tim.  What if I
> > can't access comcast's/xfinity's site?
> > "Speed tests" are a popular way bad actors get victims to sites that try
> > to extract money.   Using your ISP's test should be as safe as anything
> > from your ISP.  ShieldsUP! https://www.grc.com/ https://www.grc.com/
> > is a reputable site that
> > you can use to scan your system for internet accessible ports.
>
> Tried that this morning, from Firefox running in Fedora.  It seemed to
> think it was a windows box that I was testing.  Otherwise, the tests
> seemed to work, and claimed my workstation was clean.
> > I could not access downdetector Saturday morning.

The graph is for the past 24 hours.  I usually see problems from
coffee break to coffee break and evening peak times, so if I had
problems I check early the next morning.
> > That is what I see when I'm having problems, but once service is
> > restored I can usually see the spike in reports around the time I had
> > a problem, which means I don't pester admins at the remote site I
> > couldn't reach.
>
> I looked at that this morning to see if it would report on
> comcast/xfinity.  It did.  Would have been nice if it had given me a way
> of seeing back to Saturday morning, but I did not see any such
> functionality.
> > Compare "ss -tl" results before, during, and after a zoom session.
>
> I'll try to remember to try that.
> > I'm using a wired connection only.
> > No wifi.
> > No router.
> >
> > Are you running internet facing services (web page, ssh, etc.)?  To list
> > active tcp connections and listening ports, use "ss -tl".
> > "ShieldsUp!!": https://www.grc.com/ https://www.grc.com/ is a
> > reputable site that will tell you
> > which ports are open to the internet.
>
> This is a "simple" home workstation: tower connected via 1 yellow
> ethernet cable to one internet&voice modem.  The phone is a land line.
> I'm not running any internet-facing services that I know of.  GRC says I
> have no ports open to the internet, but it also seems to think this is a
> windows box.  (It is a Fedora and windows-7 dual boot system, but I was
> using Fedora for the GRC tests.)

I don't think GRC cares about your OS -- it can check for "most common"
ports or all ports.  Some ports were first used for Microsoft protocols,
but
Linux often provides versions of Windows services.