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author | Roger Dingledine <arma@torproject.org> | 2007-02-06 00:27:03 +0000 |
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committer | Roger Dingledine <arma@torproject.org> | 2007-02-06 00:27:03 +0000 |
commit | 9aa8e490f87a27d81dbc0863b39f6b9d0da695bb (patch) | |
tree | 539be094a718f7bd6fb839349842037ecad82d91 /doc/spec/path-spec.txt | |
parent | 6a2fe560158513e9142bd38a1a43535d87c4a825 (diff) | |
download | tor-9aa8e490f87a27d81dbc0863b39f6b9d0da695bb.tar tor-9aa8e490f87a27d81dbc0863b39f6b9d0da695bb.tar.gz |
cleanups based on looking through svn commits
svn:r9491
Diffstat (limited to 'doc/spec/path-spec.txt')
-rw-r--r-- | doc/spec/path-spec.txt | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/doc/spec/path-spec.txt b/doc/spec/path-spec.txt index ffa37d968..ec5afa361 100644 --- a/doc/spec/path-spec.txt +++ b/doc/spec/path-spec.txt @@ -270,7 +270,8 @@ of their choices. We use Guard nodes (also called "helper nodes" in the literature) to prevent certain profiling attacks. Here's the risk: if we choose entry and - exit nodes at random, and an attacker controls C out of N servers, then the + exit nodes at random, and an attacker controls C out of N servers + (ignoring advertised bandwidth), then the attacker will control the entry and exit node of any given circuit with probability (C/N)^2. But as we make many different circuits over time, then the probability that the attacker will see a sample of about (C/N)^2 @@ -298,13 +299,14 @@ of their choices. A guard is unusable for a particular circuit if any of the rules for path selection in 2.2 are not met. In particular, if the circuit is "fast" and the guard is not Fast, or if the circuit is "stable" and the guard is - not Stable, Tor can't use the guard for that circuit. + not Stable, or if the guard has already been chosen as the exit node in + that circuit, Tor can't use it as a guard node for that circuit. If the guard is excluded because of its status in the networkstatuses for over 30 days, Tor removes it from the list entirely, preserving order. If Tor fails to connect to an otherwise usable guard, it retries - periodically: every hour for six hours, every for hours for 3 days, every + periodically: every hour for six hours, every 4 hours for 3 days, every 18 hours for a week, and every 36 hours thereafter. Additionally, Tor retries unreachable guards the first time it adds a new guard to the list, since it is possible that the old guards were only marked as unreachable |