Re: [tor-relays] Sustained large spike in outbound traffic - what might be going on?

[Tim Wilson-Brown - teor <teor2345@xxxxxxxxx>]

On 23 Dec 2015, at 19:32, David Tomic <david@xxxxxxxxxxxx> wrote:

Hello everyone,

I noticed something a little bit "odd" on one of my exit relays recently, and I just wanted to ask whether anybody might be able to account for what was actually happening, and whether it's likely to warrant any further investigation?

TLDR; I noticed a fairly significant spike - in excess of 30MB/s (yes, megabytes) - of outbound traffic compared to inbound.  

http://s2.postimg.org/cvfzqvrsp/graph.png

It persisted steadily for just over an hour, until I noticed what was going on and restarted Tor (not the whole server, only Tor), at which point my traffic appeared to return to normal again.

I have this relay running a a dedicated machine, with multiple physical NICs, and the ONLY thing which should be touching this NIC is my Tor traffic.

Thoughts? 

Exit relays can end up with large traffic disparities for two reasons:

* small internet server requests can yield large internet server responses, or vice versa

* Tor cells are 512 bytes, if a small request or small response is embedded in a cell, the overhead can be quite large

This could happen because someone is uploading or downloading a large file.

But 30MB/s would probably require more than one client at the same time.

Tim

Tim Wilson-Brown (teor)

teor2345 at gmail dot com
PGP 968F094B

teor at blah dot im
OTR CAD08081 9755866D 89E2A06F E3558B7F B5A9D14F

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