Off-path round trip time measurement via TCP/IP side channels

Geoffrey Alexander, Jedidiah R. Crandall

Research output: Chapter in Book/Report/Conference proceedingConference contribution

15 Scopus citations


We present a novel technique for estimating the round trip time network latency between two off-path end hosts. That is, given two arbitrary machines, A and B, on the Internet, our technique measures the round trip time from A to B. We take advantage of information side-channels that are present in the TCP/IP network stack of modern Linux kernels to infer information about off-path routes. Compared to previous tools, ours does not require additional resources, machines, or require additional protocols beyond TCP. The only requirements are that one end host have an open port and be running a modern Linux kernel and that the other end host responds to unsolicited SYN-ACK packets with a RST packet. We evaluate our technique 'in the wild' and compare our off-path estimates to on-path measurements. Our experiments show that our technique provides accurate, real-time estimates of off-path network latency. In over 80% of measurements our technique provides off-path round trip time measurements within 20% of the actual round trip time. We also discuss possible causes of errors that impact the accuracy of our measurements.

Original languageEnglish (US)
Title of host publication2015 IEEE Conference on Computer Communications, IEEE INFOCOM 2015
PublisherInstitute of Electrical and Electronics Engineers Inc.
Number of pages9
ISBN (Electronic)9781479983810
StatePublished - Aug 21 2015
Externally publishedYes
Event34th IEEE Annual Conference on Computer Communications and Networks, IEEE INFOCOM 2015 - Hong Kong, Hong Kong
Duration: Apr 26 2015May 1 2015

Publication series

NameProceedings - IEEE INFOCOM
ISSN (Print)0743-166X


Other34th IEEE Annual Conference on Computer Communications and Networks, IEEE INFOCOM 2015
Country/TerritoryHong Kong
CityHong Kong

ASJC Scopus subject areas

  • Computer Science(all)
  • Electrical and Electronic Engineering


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