[tor-dev] Latency measurement from exits

s7r s7r at sky-ip.org
Thu Mar 10 15:15:23 UTC 2016


I haven't measured that, but maybe this is helpful: I have measured some
time ago was the latency in a hidden service (rendezvous) circuit:

Client - guard - middle - rendezvous -- middle - middle - guard - HS

[6 hops]

I did the test by installing an OpenVPN TCP server on the hidden service
that listened on and allocated VPN IP's in subnet

The client connected via Tor's socks5 to the .onion address where the
VPN server was listening and I was able to do ICMP and UDP between vpn
client (IP: and vpn server (IP:

On average the latency was about 600-700 ms. The result is heavily
dependent on all the relays in the path, so I am not sure how can we
test this to an exact value. You can try now and get lucky with only
fast relays in the path and have a 400 ms latency and you can try later
and be less lucky and have a 800 ms latency.

On 3/10/2016 4:42 PM, Zack Weinberg wrote:
> Before I go reinventing wheels, has anyone got code to measure network
> latency (either RTT or one-way packet travel time will do) from a
> chosen Tor exit to an arbitrary destination?  Latency from client to
> exit would also be useful.
> Thanks,
> zw

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