[tor-bugs] #24499 [Core Tor/Torflow]: Bandwidth determination is flawed

Tor Bug Tracker & Wiki blackhole at torproject.org
Mon Dec 4 02:31:03 UTC 2017


#24499: Bandwidth determination is flawed
------------------------------+---------------------
 Reporter:  Hassprediger      |          Owner:  tom
     Type:  defect            |         Status:  new
 Priority:  Medium            |      Milestone:
Component:  Core Tor/Torflow  |        Version:
 Severity:  Normal            |     Resolution:
 Keywords:  tor-bwauth        |  Actual Points:
Parent ID:                    |         Points:
 Reviewer:                    |        Sponsor:
------------------------------+---------------------

Comment (by starlight):

 I pulled all relays in Australia and mostly likely identified the relay
 based RelayBandwidthRate=1100.

 Two observations

 1) Some other relays with a similar RelayBandwidthRate value are rated 10x
 better, possibly due to their setting a much higher RelayBandwidthBurst
 setting.

 2) No doubt Australia is discriminated against by the Tor bandwidth
 system.  But I see unfortunately the relay resides in the "TPG Telecom
 Limited" network.  No relay in that Autonomous System (AS) garners a
 decent rating.  Appears to me this is a situation where the bandwidth
 authorities are performing to some degree as intended and granting a low
 score to relays with poor effective reachability.  This extract from
 Blutmagie illustrates {flags, name, ASN, cntry, avg-bw, cons-wght, days-
 up, ver, IP}:

 {{{
 __fs_ xwn2                  7545 AU    80    148   3 0.10 L 61.69.170.220
 9001  None  C-61-69-170-220.syd.connect.net.au
 __fs_ Unnamed               7545 AU    32     56   9 0.9  L 59.102.75.64
 9001  9030  59-102-75-64.tpgi.com.au
 ___s_ BrutalesArschloch     7545 AU    21     23  15 1.8  L 60.240.245.76
 1000  1001  60-240-245-76.static.tpgi.com.au
 __f__ magnetic              7545 AU     8     83   8 0.10 L 220.245.192.5
 9002  None  220-245-192-5.tpgi.com.au
 e____ 73rmin470rx           7545 AU     7      3   2 5.14 L 14.202.230.49
 9001  None  14-202-230-49.static.tpgi.com.au
 ___s_ Unnamed               7545 AU     3     30  31 5.14 L 220.245.39.46
 9001  9030  220-245-39-46.tpgi.com.au
 e__s_ WeekliLeaks           7545 AU     3      1  45 4.23 W 110.174.43.136
 444   None  110-174-43-136.static.tpgi.com.au
 _____ Punani4life           7545 AU     1      1   1 4.27 L
 210.185.117.161 443   9030  210-185-117-161.tpgi.com.au
 _____ UbuntuCore201         7545 AU     0      6   0 1.9  L 203.221.63.34
 44431 None  203-221-063-34.tpgi.com.au
 ___s_ ididnteditheconfig    7545 AU     0      3  14 9.11 L 110.175.89.172
 9538  None  110-175-89-172.static.tpgi.com.au
 }}}

 Choopa looks better:

 {{{
 __fs_ itsarelay            20473 AU   101    384  17 8.8  L 108.61.96.230
 9001  None  108.61.96.230.vultr.com
 __fs_ Someone              20473 AU    94    310  18 0.10 L 45.32.245.73
 9001  None  45.32.245.73.vultr.com
 __fs_ HeirloomReaper       20473 AU    91    219  36 1.7  L 45.63.24.164
 9001  9030  heirloom.for-no-reason.net
 e_fs_ birdyExit            20473 AU    78     94   5 9.13 L 45.76.115.159
 443   80    45.76.115.159.vultr.com
 __fs_ huntersthompson      20473 AU    78    225   0 1.9  L 45.63.25.179
 9001  None  45.63.25.179.vultr.com
 __fs_ pol                  20473 AU    58    304 114 5.14 L 45.76.119.205
 443   80    45.76.119.205.vultr.com
 __fs_ ZcashTor0au          20473 AU    51    131   6 1.8  L 45.32.246.15
 20    21    45.32.246.15
 __fs_ lochland             20473 AU    43    155  25 9.11 L 45.63.26.48
 9001  None  45.63.26.48.vultr.com
 __fs_ IcelandicTorProject  20473 AU    41    270   3 9.11 L 45.76.112.223
 9001  9030  sydney.govt.is
 __fs_ MidgarSector5        20473 AU    41    128 170 5.14 L 45.32.240.31
 443   80    45.32.240.31.vultr.com
 }}}

 I would try removing the bandwidth maximum and tuning IP before giving up.
 Try this in `sysctl.conf`:

 {{{
 # Increase socket limits.
 net.core.rmem_max = 4194304
 net.core.wmem_max = 4194304
 net.ipv4.tcp_wmem = 4096  250000  4194304
 net.ipv4.tcp_rmem = 4096  375000  4194304
 }}}

 run `sysctl -p` after editing the file.

 Also IMO it's not unreasonable to pull some data through a relay as you
 describe to increase the self-measure bandwidth to a realistic
 representation of available capacity.  Something like a 5-or-10 minute
 burst of activity twice a day should be sufficient to register with the
 self-measure logic.  Combined with the other changes this could tip the
 relay into a higher scanner "band" where it may receive better treatment.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/24499#comment:5>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
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