[zeromq-dev] SOLUTION-- Encryption failure problem and wireless connectivity

[Pieter Hintjens]

Since CurveZMQ runs over TCP, and the encryption is entirely
abstracted from the network, this is probably coincidence.

On Thu, Dec 11, 2014 at 4:17 PM, Steve Murphy <murf at parsetree.com> wrote:
> Hello, fellow zeromq devs!
>
> Some months ago, I posted a problem I was having,
> that was quite vexing. Since then, I figured it out, and
> thought I should share before it completely gets forgotten.
>
> The problem appeared at first blush, to be an incompatibility
> between Ubuntu and CentOS. My home node is running
> Ubuntu, and all my other nodes were mostly CentOS. All
> the CentoOS nodes were behaving normally, with CURVE
> encryption between them. But on my home Ubuntu machine,
> the same code would not establish an encrypted connection.
>
> At last, after wiresharking the back and forth protocol of CURVE
> encryption, I saw that the protocol seemed to get to a certain
> stage, and then just quit. I delved deeper and deeper into the code
> underneath, and still, no particular failure point!
>
> Then it hit me: My home is connected to the internet via a wireless
> connection. Could it be my connection? I did an MTR betwen my home
> machine and the other centOS mechines, and sure enough, I was
> seeing a 50% packet loss! I had not noticed any performance drop
> in my connection; no slowdowns. Normally mtr between my home and
> the internet is pretty clean, but that week, it was a bit shaky.
>
> Moved the testing off my machine and no problem.
>
> So, I think I may have a found a packet loss percentage at which
> CURVE encryption will no longer operate (but unencrypted connections will),
> but, to be fair, the connection is via Motorola Canopy hardware, and the
> other end of the link is somewhere near 6 miles away. Packet losses
> in that environment could get somewhat selective as to size or timing.
>
> Just a heads-up to the other newbies on this mailing list, of a possible
> pitfall, and how to detect it.
>
> murf
>
>
>
> --
>
> Steve Murphy
> ParseTree Corporation
> 57 Lane 17
> Cody, WY 82414
> ✉  murf at parsetree dot com
> ☎ 307-899-5535
>
>
>
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