Opened 23 months ago

Last modified 10 months ago

#28860 new defect

Increased DNS failure rate when using ServerDNSResolvConfFile with tor (as opposed to 0.3.3.x)

Reported by: nusenu Owned by:
Priority: Medium Milestone: Tor: unspecified
Component: Core Tor/Tor Version:
Severity: Normal Keywords: tor-dns, regression, 040-deferred-20190220, network-health
Cc: Actual Points:
Parent ID: Points:
Reviewer: Sponsor:


A major tor exit relay operator reports that
after upgrading from 0.3.3.x to his DNS failure rate significantly increased.

He also reported that he is observing DNS issues only when using ServerDNSResolvConfFile and no problems when not using that config option.
Using that option worked fine on tor 0.3.3.x

With ServerDNSResolvConfFile option on

Dec 13 02:39:52.000 [notice] eventdns: Nameserver is back up
Dec 13 02:39:53.000 [warn] eventdns: All nameservers have failed

Child Tickets

Change History (8)

comment:1 Changed 23 months ago by dgoulet

Keywords: tor-dns regression added
Milestone: Tor: 0.4.0.x-final

comment:2 Changed 23 months ago by arma


I don't know where to start here.

Is the person on the same version of libevent the whole time?

comment:3 Changed 23 months ago by nickm is google; it might be better on a relay not to use Google's DNS. I don't think that's the root problem here, though.

comment:4 Changed 23 months ago by arma

When you say 0.3.3.x, what is x?

For example I see that #21394 went in to

comment:5 Changed 21 months ago by nickm

Keywords: 040-deferred-20190220 added
Milestone: Tor: 0.4.0.x-finalTor: unspecified

Deferring 51 tickets from 0.4.0.x-final. Tagging them with 040-deferred-20190220 for visibility. These are the tickets that did not get 040-must, 040-can, or tor-ci.

comment:6 Changed 16 months ago by cypherpunks


Tor Exit Failures

Average probability-weighted failure rate: 7.1%

Test ran at 2019-07-12 12:14:00 UTC


Top-5 bad exits are on Tor!

failure_rate	connection_time	nickname	fingerprint	as_name	country_name	contact	platform	bandwidth_rate	exit_probability
80.0	0.8471200466156006	renewablefreedom	CA94704217260E7483DA88719CACD7A94C564D5C	Zwiebelfreunde e.V.	Germany <support .AT. torservers .DOT. net>	Tor on Linux	52428800	0.005871822
80.0	0.7933343648910522	iVPN	A2534EF23390CAE079B1586F0FDF9CE11F556062	Zwiebelfreunde e.V.	Germany <support .AT. torservers .DOT. net>	Tor on Linux	52428800	0.0056790924
80.0	0.8955183029174805	RSFPressFreedom	A2DB293FFC5A76A718863BF1AEDBC8DFB1CB1097	Zwiebelfreunde e.V.	Germany	Exit by Reporters without Borders via	Tor on Linux	52428800	0.0055955765
80.0	0.8538782596588135	AnosognosiaRedux	D6D6B6614C9EF2DAD13AC0C94487AD8ED3B6877F	Zwiebelfreunde e.V.	Germany <support .AT. torservers .DOT. net>	Tor on Linux	52428800	0.005524909
90.0	1.153367280960083	HSLtor	E43A346CB81DDF364B6FF68235AFADBA0E8692B8	Zwiebelfreunde e.V.	Germany <support .AT. torservers .DOT. net>	Tor on Linux	31457280	0.0048182346
70.0	3.1669646898905435	dorrisdeebrown	FDAED15C98CFE7A416E5676F614254F78406105C	Zwiebelfreunde e.V.	Germany <support .AT. torservers .DOT. net>	Tor on Linux	52428800	0.0060902485

comment:7 Changed 16 months ago by cypherpunks

this s no "bad" exits. This are highest traffic relays. It can have many reasons like timeouts. Feel free to keep contact with them: to investigate issues

comment:8 Changed 10 months ago by gk

Keywords: network-health added
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