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49 lines
1.4 KiB
Plaintext
49 lines
1.4 KiB
Plaintext
Filename: 107-uptime-sanity-checking.txt
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Title: Uptime Sanity Checking
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Version:
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Last-Modified:
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Author: Kevin Buaer and Damon McCoy
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Created: 8-March-2007
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Status: Open
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Overview:
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This document describes how to cap the uptime that is used when computing
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which routers are maked as stable such that highly stable routers cannot
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be displaced by malicious routers that report extremely high uptime
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values.
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This is similar to how bandwidth is capped at 1.5MB/s.
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Motivation:
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It has been pointed out that an attacker can displace all stable nodes and
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entry guard nodes by reporting high uptimes. This is an easy fix that will
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prevent highly stable nodes from being displaced.
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Security implications:
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It should decrease the effectiveness of routing attacks that report high
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uptimes while not impacting the normal routing algorithms.
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Specification:
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We propose that uptime be capped at two months. Currently there are
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approximetly 50 nodes with this amount of uptime, and the average uptime
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is around 9 days. This cap would prevent these 50 nodes from being
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displaced by an attacker.
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Compatibility:
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There should be no compatiblity issues due to uptime capping.
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Implementation:
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#define MAX_BELIEVABLE_UPTIME 60*24*60*60
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dirserv.c
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1448: *up = (uint32_t) real_uptime(ri, now);
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if(*up > MAX_BELIEVABLE_UPTIME) {
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*up = MAX_BELIEVABLE_UPTIME;
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}
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