Almost Beta 2 Cloud Storage fails

[Linus Torvalds]

On Mon, Sep 21, 2015 at 1:30 PM, Rick Walsh <rickmwalsh at gmail.com> wrote:
>
>
> FWIW, here's the traceroute.
>
> traceroute to cloud.subsurface-divelog.org (52.25.223.173), 30 hops max, 60 byte packets
>  1  gateway (192.168.1.1)  1.045 ms  1.680 ms  1.775 ms
>  2  lo0.bng1.mel4.on.ii.net (150.101.32.44)  14.045 ms  15.004 ms  16.828 ms
...
> 25  * * *
> 26  * * *
> 27  * * *
> 28  * * *
> 29  * * *
> 30  * * *
>
> I've never used traceroute before, so don't know if that's what it's
> supposed to do, but I don't get the *** entries if for example I traceroute
> www.subsurface-divelog.org

traceroute only works if the connection between the hosts

 (a) allows random UDP packets

 (b) pass back the ICMP "time exceeded" packet

and most cloud networks don't do either of those. So traceroute
generally won't be showing you anything past the entrypoint into the
cloud network.

Sometimes it's just a particular router that simply drops TTL-limited
packets silently (and then you generally see the '* * *" in the middle
but it resumes past that pointer).

In some situations it *may* be just the UDP packets that end up
filtered, and you can use traceroute with TCP instead ("traceroute -T"
uses TCP SYN packets), but then you want root.

For cloud.subsurface-divelog.org it looks like you can actually do
that TCP SYN thing.

Anyway, "traceroute" not seeing the route does not mean that it
doesn't work fine.

Similarly, "ping" not working is often just because people have turned
off ICMP ECHO, not necessarily at all because the host isn't actually
reachable.

                        Linus