[or-cvs] r14509: Added proposal 135: Simplify Configuration of Private Tor Ne (tor/trunk/doc/spec/proposals)
kloesing at seul.org
kloesing at seul.org
Tue Apr 29 20:36:51 UTC 2008
Author: kloesing
Date: 2008-04-29 16:36:51 -0400 (Tue, 29 Apr 2008)
New Revision: 14509
Added:
tor/trunk/doc/spec/proposals/135-private-tor-networks.txt
Modified:
tor/trunk/doc/spec/proposals/000-index.txt
Log:
Added proposal 135: Simplify Configuration of Private Tor Networks
Modified: tor/trunk/doc/spec/proposals/000-index.txt
===================================================================
--- tor/trunk/doc/spec/proposals/000-index.txt 2008-04-29 19:51:38 UTC (rev 14508)
+++ tor/trunk/doc/spec/proposals/000-index.txt 2008-04-29 20:36:51 UTC (rev 14509)
@@ -57,6 +57,7 @@
132 A Tor Web Service For Verifying Correct Browser Configuration [DRAFT]
133 Incorporate Unreachable ORs into the Tor Network [DRAFT]
134 More robust consensus voting with diverse authority sets [DRAFT]
+135 Simplify Configuration of Private Tor Networks [OPEN]
Proposals by status:
@@ -71,6 +72,7 @@
OPEN:
120 Suicide descriptors when Tor servers stop
121 Hidden Service Authentication
+ 135 Simplify Configuration of Private Tor Networks
NEEDS-REVISION:
110 Avoiding infinite length circuits
117 IPv6 exits
Added: tor/trunk/doc/spec/proposals/135-private-tor-networks.txt
===================================================================
--- tor/trunk/doc/spec/proposals/135-private-tor-networks.txt (rev 0)
+++ tor/trunk/doc/spec/proposals/135-private-tor-networks.txt 2008-04-29 20:36:51 UTC (rev 14509)
@@ -0,0 +1,155 @@
+Filename: 135-private-tor-networks.txt
+Title: Simplify Configuration of Private Tor Networks
+Version: $LastChangedRevision$
+Last-Modified: $LastChangedDate$
+Author: Karsten Loesing
+Created: 29-Apr-2008
+Status: Open
+
+Change history:
+
+ 29-Apr-2008 Initial proposal for or-dev
+
+Overview:
+
+ Configuring a private Tor network has become a time-consuming and
+ error-prone task with the introduction of the v3 directory protocol. In
+ addition to that, operators of private Tor networks need to set an
+ increasing number of non-trivial configuration options, and it is hard
+ to keep FAQ entries describing this task up-to-date. In this proposal we
+ (1) suggest to (optionally) accelerate timing of the v3 directory voting
+ process and (2) introduce an umbrella config option specifically aimed at
+ creating private Tor networks.
+
+Design:
+
+ 1. Accelerate Timing of v3 Directory Voting Process
+
+ Tor has reasonable defaults for setting up a large, Internet-scale
+ network with comparably high latencies and possibly wrong server clocks.
+ However, those defaults are bad when it comes to quickly setting up a
+ private Tor network for testing, either on a single node or LAN (things
+ might be different when creating a test network on PlanetLab or
+ something). Some time constraints should be made configurable for private
+ networks. The general idea is to accelerate everything that has to do
+ with propagation of directory information, but nothing else, so that a
+ private network is available as soon as possible. (As a possible
+ safeguard, changing these configuration values could be made dependent on
+ the umbrella configuration option introduced in 2.)
+
+ 1.1. Initial Voting Schedule
+
+ When a v3 directory does not know any consensus, it assumes an initial,
+ hard-coded VotingInterval of 30 minutes, VoteDelay of 5 minutes, and
+ DistDelay of 5 minutes. This is important for multiple, simultaneously
+ restarted directory authorities to meet at a common time and create an
+ initial consensus. Unfortunately, this means that it may take up to half
+ an hour (or even more) for a private Tor network to bootstrap.
+
+ We propose to make these three time constants configurable (note that
+ V3AuthVotingInterval, V3AuthVoteDelay, and V3AuthDistDelay do not have an
+ effect on the _initial_ voting schedule, but only on the schedule that a
+ directory authority votes for). This can be achieved by introducing three
+ new configuration options: V3AuthInitialVotingInterval,
+ V3AuthInitialVoteDelay, and V3AuthInitialDistDelay.
+
+ As first safeguards, Tor should only accept configuration values for
+ V3AuthInitialVotingInterval that divide evenly into the default value of
+ 30 minutes. The effect is that even if people misconfigured their
+ directory authorities, they would meet at the default values at the
+ latest. The second safeguard is to allow configuration only when the
+ umbrella configuration option PrivateTorNetwork is set.
+
+ 1.2. Immediately Provide Reachability Information (Running flag)
+
+ The default behavior of a directory authority is to provide the Running
+ flag only after the authority is available for at least 30 minutes. The
+ rationale is that before that time, an authority simply cannot deliver
+ useful information about other running nodes. But for private Tor
+ networks this may be different. This is currently implemented in the code
+ as:
+
+ /** If we've been around for less than this amount of time, our
+ * reachability information is not accurate. */
+ #define DIRSERV_TIME_TO_GET_REACHABILITY_INFO (30*60)
+
+ There should be another configuration option DirAssumeRunningDelay with
+ a default value of 30 minutes that can be changed when running private
+ Tor networks, e.g. to 0 minutes. The configuration value would simply
+ replace the quoted constant. Again, changing this option could be
+ safeguarded by requiring the umbrella configuration option
+ PrivateTorNetwork to be set.
+
+ 1.3. Reduce Estimated Descriptor Propagation Time
+
+ Tor currently assumes that it takes up to 10 minutes until router
+ descriptors are propagated from the authorities to directory caches.
+ This is not very useful for private Tor networks, and we want to be able
+ to reduce this time, so that clients can download router descriptors in a
+ timely manner.
+
+ /** Clients don't download any descriptor this recent, since it will
+ * probably not have propagated to enough caches. */
+ #define ESTIMATED_PROPAGATION_TIME (10*60)
+
+ We suggest to introduce a new config option
+ EstimatedDescriptorPropagationTime which defaults to 10 minutes, but that
+ can be set to any lower non-negative value, e.g. 0 minutes. The same
+ safeguards as in 1.2 could be used here, too.
+
+ 2. Umbrella Option for Setting Up Private Tor Networks
+
+ Setting up a private Tor network requires a number of specific settings
+ that are not required or useful when running Tor in the public Tor
+ network. Instead of writing down these options in a FAQ entry, there
+ should be a single configuration option, e.g. PrivateTorNetwork, that
+ changes all required settings at once. Newer Tor versions would keep the
+ set of configuration options up-to-date. It should still remain possible
+ to manually overwrite the settings that the umbrella configuration option
+ affects.
+
+ The following configuration options are set by PrivateTorNetwork:
+
+ - ServerDNSAllowBrokenResolvConf 1
+ Ignore the situation that private relays are not aware of any name
+ servers.
+
+ - DirAllowPrivateAddresses 1
+ Allow router descriptors containing private IP addresses.
+
+ - EnforceDistinctSubnets 0
+ Permit building circuits with relays in the same subnet.
+
+ - AssumeReachable 1
+ Omit self-testing for reachability.
+
+ - AuthDirMaxServersPerAddr 0
+ - AuthDirMaxServersPerAuthAddr 0
+ Permit an unlimited number of nodes on the same IP address.
+
+ - ClientDNSRejectInternalAddresses 0
+ Believe in DNS responses resolving to private IP addresses.
+
+ - ExitPolicyRejectPrivate 0
+ Allow exiting to private IP addresses. (This one is a matter of
+ taste---it might be dangerous to make this a default in a private
+ network, although people setting up private Tor networks should know
+ what they are doing.)
+
+ - V3AuthVotingInterval 5 minutes
+ - V3AuthVoteDelay 20 seconds
+ - V3AuthDistDelay 20 seconds
+ Accelerate voting schedule after first consensus has been reached.
+
+ V3AuthInitialVotingInterval 5 minutes
+ V3AuthInitialVoteDelay 20 seconds
+ V3AuthInitialDistDelay 20 seconds
+ Accelerate initial voting schedule until first consensus is reached.
+
+ DirAssumeRunningDelay 0 minutes
+ Consider routers as Running from the start of running an authority.
+
+ EstimatedDescriptorPropagationTime 0 minutes
+ Clients try downloading router descriptors from directory caches,
+ even when they are not 10 minutes old.
+
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