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Some notes on an implementation plan:
Switch to one guard per client
- Look into
decide_num_guards(). - See if setting
NumEntryGuards=1breaks any assumption of the rest of the code. - Implementation depends on whether we pick alternative behavior of section 1.1.1 or not.
Increase guard rotation period
- Either play with
MIN_GUARD_LIFETIMEor use theGuardLifetimeconsensus option. - Implementation depends on whether we pick alternative behavior of section 1.2.1 or not.
Raise bw thresholds for guard
- See
set_routerstatus_from_routerinfo()andAuthDirGuardBWGuaranteeetc. - How to test: Make fake network and see which guards are eligible to become guards
Prioritize young guards for non-guard tasks
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Implementation plan: Download/parse/verify old consensuses in an external script, write file with results, have little-t-tor read the results.
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Bandwidth authorities: See
dirserv_read_measured_bandwidths()and https://gitweb.torproject.org/torflow.git/blob/HEAD:/NetworkScanners/BwAuthority/README.spec.txt#l333 -
How to test the external script: Make artificial data sets of consensuses and see if the external script parses them properly.
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How to test Tor: Create artificial guard age results file, give the test a fake network (some relays) and see if Tor generates the right weights for the relays.
- Look into
Replying to asn:
== Prioritize young guards for non-guard tasks ==
- Implementation plan: Download/parse/verify old consensuses in an external script, write file with results, have little-t-tor read the results.
Two questions on this task (also see #10968 (moved)):
a) How are we going to get past consesuses? AFAIK, directories don't keep and serve old consesuses. Is metrics.tpo the only place where we can get them? Is it reasonalbe to make metrics.tpo a single point of failure for this feature?
b) We will need to verify the sigs of the past consesuses. Can arm verify signatures of Tor documents? Also, what can go wrong with verifying consesus sigs from many months ago? Have auths ever changed their identity keys? Also, what happens if we try to parse a badly-signed consesus? Should we just ignore it?
We also need to decide if we want to do the alternative behaviors suggested in sections
1.1.1and1.2.1of https://gitweb.torproject.org/torspec.git/blob/HEAD:/proposals/236-single-guard-node.txt
Replying to asn:
Replying to asn:
== Prioritize young guards for non-guard tasks ==
- Implementation plan: Download/parse/verify old consensuses in an external script, write file with results, have little-t-tor read the results.
Two questions on this task (also see #10968 (moved)):
a) How are we going to get past consesuses? AFAIK, directories don't keep and serve old consesuses. Is metrics.tpo the only place where we can get them? Is it reasonalbe to make metrics.tpo a single point of failure for this feature?
Would somebody want to run a fall-back instance of the part of metrics.tpo that archives consensuses? I run two instances, but I sure wouldn't mind knowing that there's another instance running that is not run by me.
b) We will need to verify the sigs of the past consesuses. Can arm verify signatures of Tor documents?
stem, not arm. That's a question for atagar.
Also, what can go wrong with verifying consesus sigs from many months ago? Have auths ever changed their identity keys?
metrics.tpo also serves past certificates that you could use here. You'll also want to extract a list of authority identities that little-t-tor clients considered valid. That list changes every now and then, but not very often.
Also, what happens if we try to parse a badly-signed consesus? Should we just ignore it?
Probably warn about the bad signature and ignore it. If the consensus still has enough good signatures for little-t-tor clients to accept it, you can probably accept it, too.
b) We will need to verify the sigs of the past consesuses. Can arm verify signatures of Tor documents?
stem, not arm. That's a question for atagar.
Stem can check the server descriptor digestests if you have PyCrypto available...
https://gitweb.torproject.org/stem.git/blob/HEAD:/stem/descriptor/server_descriptor.py#l717
... but it doesn't yet check the consensus signatures. Patches welcome. :)
Trac:
Parent: N/A to #11045 (closed)
Trac:
Parent: #11045 (closed) to N/AThis will be done when #12598 (moved) is done; moving to 0.2.7
Trac:
Milestone: Tor: 0.2.6.x-final to Tor: 0.2.7.x-final
