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Re: Is there a way to know the ISP with the default installation of Stretch?

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On Wed, Jan 03, 2018 at 07:04:46PM -0600, David Wright wrote:
>(In view of
>https://lists.debian.org/debian-user/2018/01/msg00126.html
>do you mean public?)

No, it's a pretty common shorthand to say "routable" to mean "routable 
on the public internet", especially where there's no real possibility of 
confusing it with specifically non-routable blocks like 127.0.0.0/8.  
Honestly, I considered it less likely to be confusing than calling them 
RFC1918 addresses in this context. 

As far as 169.254.0.0/16, it's defined as a link local range for address 
autoconfiguration, but it can still be routed internally just as much as 
the RFC1918 space can be. (Doing so just might not be a good idea, 
because some devices might code in some assumptions or add a zeroconf 
route by default. Which is annoying because the whole automatic zero 
knowledge IPv4 autoconfiguration thing is just a spectacularly bad idea 
anyway that typically causes far more trouble than it's worth. I guess 
it was useful back in the days when someone might want to connect two 
win98 machines together to copy a file without using a floppy disk but 
couldn't think of a reason they might want to use the internet.) IPv6 
has an entirely different (and more useful) concept of link local 
addresses. Some of the other reserved ranges can also be internally 
routed in practice, so trying to distinguish between "routable" and 
"non routable" for some meaning other than "not routable on the public 
internet" rapidly becomes a game of semantics and implementations.

>But in that case, would https://www.whatismyip.com/ reveal an address
>closer to the OP than whoever is providing *their* internet access?
>(IOW does https://www.whatismyip.com/ ever yield a private address?)

No, it can't. It will show a public IP that connections from the web 
client to connect to that particular web site, not a private IP. In the 
case of a NAT environment there may be multiple different IPs in use, or 
there may be different IPs for different routes, but there's no reliable 
way to enumerate every possible IP you might be NATed to.

Back to the traceroute idea: it's fairly common for a residential 
endpoint to have a publically routable IP (usually on the router or 
"modem") but traceroute won't help identify that--instead, you'll see 
the private IP that the modem uses to communicate with the machine 
running traceroute.  (In general, traceroute will only show one of many 
IPs that a particular hop has.) So what you're getting from traceroute 
isn't going to be the IP you use when communicating with web sites, it's 
going to be the IP your router uses to communicate with you, then IPs 
associated with other routers along the way (some of which may also be 
using RFC1918 space, though it's more common these days for large 
providers to just pass around encapsulated traffic in a way that's 
opaque to traceroute, likely over IPv6). In theory another option for 
finding the public-side gateway IP is UPnP IGD or PCP, but I wouldn't 
expect those to work on any arbitrary network.

Mike Stone

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Is there a way to know the ISP with the default installation of  Stretch? Max Power <debian@cpnetserver.net> - 2018-01-02 12:50 +0100
  Re: Is there a way to know the ISP with the default installation of  Stretch? <tomas@tuxteam.de> - 2018-01-02 13:00 +0100
    Re: Is there a way to know the ISP with the default installation of  Stretch? Curt <curty@free.fr> - 2018-01-02 14:10 +0100
      Re: Is there a way to know the ISP with the default installation of  Stretch? <tomas@tuxteam.de> - 2018-01-02 15:00 +0100
        Re: Is there a way to know the ISP with the default installation of  Stretch? Jonathan Dowland <jmtd@debian.org> - 2018-01-02 17:30 +0100
  Re: Is there a way to know the ISP with the default installation of  Stretch? Michael Stone <mstone@debian.org> - 2018-01-02 14:30 +0100
  Re: Is there a way to know the ISP with the default installation of  Stretch? Greg Wooledge <wooledg@eeg.ccf.org> - 2018-01-02 17:20 +0100
    Re: Is there a way to know the ISP with the default installation of   Stretch? Dan Purgert <dan@djph.net> - 2018-01-02 18:40 +0100
    Re: Is there a way to know the ISP with the default installation of  Stretch? David Wright <deblis@lionunicorn.co.uk> - 2018-01-03 10:30 +0100
      Re: Is there a way to know the ISP with the default installation of   Stretch? Dan Purgert <dan@djph.net> - 2018-01-03 14:10 +0100
        Re: Is there a way to know the ISP with the default installation of Stretch? rhkramer@gmail.com - 2018-01-03 16:40 +0100
          Re: Is there a way to know the ISP with the default installation of  Stretch? Nicolas George <george@nsup.org> - 2018-01-03 17:00 +0100
          Re: Is there a way to know the ISP with the default installation of  Stretch? Michael Stone <mstone@debian.org> - 2018-01-03 19:50 +0100
            Re: Is there a way to know the ISP with the default installation of  Stretch? David Wright <deblis@lionunicorn.co.uk> - 2018-01-04 02:10 +0100
              Re: Is there a way to know the ISP with the default installation of  Stretch? Michael Stone <mstone@debian.org> - 2018-01-04 05:40 +0100
                Re: Is there a way to know the ISP with the default installation of  Stretch? Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-01-07 14:40 +0100
            Re: Is there a way to know the ISP with the default installation of Stretch? rhkramer@gmail.com - 2018-01-04 02:30 +0100
      Re: Is there a way to know the ISP with the default installation of  Stretch? Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-01-03 21:00 +0100
  Re: Is there a way to know the ISP with the default installation of   Stretch? Dan Purgert <dan@djph.net> - 2018-01-02 17:20 +0100
    Re: Is there a way to know the ISP with the default installation of  Stretch? <tomas@tuxteam.de> - 2018-01-03 09:20 +0100
      Re: Is there a way to know the ISP with the default installation of   Stretch? Dan Purgert <dan@djph.net> - 2018-01-03 13:10 +0100

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