[sf-lug] tcptraceroute, traceroute, Westell, ... Got router? / Where *is* that ("other") router? (linuxmafia.com)

[Justin Noor]

I meet a lot of people who’ve had issues with AT&T modems. Of course there
are too many variables to name, but could there ever be an open source DSL
modem for AT&T? Routers can use Linux, however, they are still burdened
with the issue of double-NAT-ing because they have to be plugged into
AT&T’s modem. This is okay for surfing the net, but for home networking it
becomes a problem, requiring the router to be placed inside of the DMZ,
which seems hacky sometimes.


On Thu, Oct 25, 2018 at 8:40 PM Michael Paoli <
Michael.Paoli at cal.berkeley.edu> wrote:

> tcptraceroute ... traceroute ...
>
> Newer versions of traceroute - at least for (most) Linux distributions,
> have doing traceroute using TCP as a built-in capability,
> most notably take a look at the -T and -p (for port) options.
>
> So, in that regard, tcptraceroute has essentially been superceded by
> newer functionality of traceroute.
>
> Even MacOS has a traceroute that can do that (or so its man page
> claims) ... though "of course" it has quite different syntax.
>
> In any case, doing a [tcp]traceroute, using TCP, and to specific
> target port can be highly useful ... most notably firewalls -
> often only specific traffic is allowed through the firewall(s), and
> other traffic is blocked or dropped - so doing the trace with TCP
> (or UDP, if that's what's used for the service of interest) and to
> the applicable target port of the service, can be more useful and
> informative than a more typical traceroute (UDP, high numbered sequence of
> ports - the default behavior).
>
> Westell - I still have two such ADSL "modems", same model, slightly
> different firmware versions ... one I'd upgraded, one I left with the
> version it had on it.  Both suffer from occasional issue - typically
> about once a month or so - on average, that goes about like this (from
> typical log entry):
> 2018-06-08
> lost Internet IP connectivity over DSL
> DSL modem shows three solid green lights on top
> unable to ping router IP 198.144.194.233
> power cycled DSL modem - this corrected the problem
>
> Let's see ... which ones have I got ...
> (again, ye olde log file of mine) ...
> WESTELL , INC. MODEL : B90 - 36R516 REV : G S/N 00ST05163539
> WESTELL , INC. MODEL : B90 - 36R516 REV : E S/N 00B404282008
>
> Never know exactly when they'll fail, ... but doing a pre-emptive
> power cycling of them (I sometimes do that), seems to either put the
> problem off some fair while, or at least *seems to* make it less probable
> to occur relatively soon after.  But not sure I've captured enough data
> (nor care to?) to fully statistically analyze that.
>
> I likely have some of the applicable firmware files ... *somewhere*.
> I'm sure it's designed to be updated with (ugh) Microsoft Windows,
> ... but there must also be other ways.  :-)
>
> So, yes, I have a spare ... but good to have backup(s)/redundancy ...
> sometimes I swap 'em out (or loan one out - have done that at least once
> thus far).
> I do have (at least?) one other ADSL "modem" ... haven't tested it as
> rigorously, so don't know if it's more (or less) reliable, etc.
>
> > From: "Rick Moen" <rick at linuxmafia.com>
> > Subject: Re: [sf-lug] Got router? / Where *is* that ("other")
> > router? (linuxmafia.com)
> > Date: Thu, 25 Oct 2018 18:12:22 -0700
>
> > Quoting Michael Paoli (Michael.Paoli at cal.berkeley.edu):
> >
> >> So, I noticed earlier, when linuxmafia.com had bit earlier been
> ungraciously
> >> disconnected from the Internet by AT&T ...
> >>
> >> When I did a traceroute from my host(s) at home,
> >> I only saw one hop beyond host itself.
> > [...]
> >
> > Thanks for the probing results.  I've been meaning to do some
> > poking around too, but haven't had a chance, yet.  (There's a lot of
> > correspondence to do, for one thing.)  tcptraceroute might be more
> > enlightening:  Sometimes, devices have been configured to not
> > respond to ICMP echo on some dumb 'How to not be seen' theory
> > (cue Monty Python skit).
> >
> > Among the things I am contemplating is a cross-check to see whether
> > my 16-year-old Westell ADSL bridge device has a hardware fault or
> > not.  The earlier surmise to that effect is logically open to
> > question.
> >
> > _Or_ I could just decide it doesn't matter, and discard it.
>
>
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