I noticed something when letting a relay (non exit) run for a few days: The amount of traffic sent is larger than the amount received. This is confirmed by looking at the tor log and also by looking at ifconfig. Examples of one day:

[...]I've sent 556.92 GB and received 456.66 GB.

[...]I've sent 670.04 GB and received 546.71 GB.

[...]I've sent 861.17 GB and received 687.35 GB.

[...]I've sent 1060.14 GB and received 849.68 GB.

Why is that? From my understanding the relay has to forward any traffic it receives from a client or an entry node to the next relay or the exit. Any reply will also flow through the relay the other way around. Shouldn't the amounts of data roughly match?

  • 1
    You mean the amount sent is larger than the amount received?
    – user194
    Oct 10, 2013 at 21:25
  • Yes, as you can see in the log excerpts above
    – leepfrog
    Oct 10, 2013 at 22:01
  • 1
    What user194 means is that you're saying the opposite in your question. Edited, will be visible once peer-reviewed.
    – karsten
    Oct 11, 2013 at 6:47

1 Answer 1


Did you open the DirPort on your relay? That would make your relay a directory mirror which answers directory requests of clients. A directory request is typically quite small ("please give me the current consensus"), but the response can be quite big ("here is the list of the 4400 currently running relays"). That would explain the difference between sent and received bytes.

  • Sure, that makes absolutly sense - should have thought of that. Thanks!
    – leepfrog
    Oct 11, 2013 at 8:02

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