2013-10-11 08:47:06 +08:00
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Currently an attacker with sufficient resources could launch a large scale
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denial of service type attack by flooding the Tox network with a bunch of nodes
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that do not act like real nodes to prevent people from finding each other.
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Due to the design of Tox, this is the worst thing an attacker can do to disrupt
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the network.
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This solution's goal is to make these denial of service attack very very hard
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to accomplish.
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For the network to work every Tox node must:
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1. Respond to ping requests.
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2. Respond to get node requests with the ids of nodes closest to a queried id
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(It is assumed each nodes know at least the 32 nodes closest to them.)
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3. Properly send crypto request packets to their intended destination.
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Currently the only thing a node needs to do to be part of the network is
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respond correctly to ping requests.
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The only people we really trust on the network are the nodes in our friends
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list.
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The behavior of each Tox node is easily predictable this means that it possible
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for Tox nodes to test the nodes that they are connected to to see if they
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behave like normal Tox nodes and only send nodes that are confirmed to behave
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like real Tox nodes as part of send node replies when other nodes query them.
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If correctly done, this means that to poison the network an attacker can only
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infiltrate the network if his "fake" nodes behave exactly like real nodes
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completely defeating the purpose of the attack. Of course nodes must be
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rechecked regularly to defeat an attack where someone floods the network with
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many good nodes then suddenly turns them all bad.
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This also prevents someone from accidentally killing the tox network with a bad
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implementation of the protocol.
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Implementation ideas (In Progress):
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1. Use our friends to check if the nodes in our close list are good.
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EX: If our friend queries a node close to us and it correctly returns our
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ip/port and then sends a crypto request packet to it and it routes it correctly
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to us then it is good.
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Problems with this: People don't always have at least one online friend.
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2013-10-31 08:25:02 +08:00
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2. Pick random nodes (add ourselves some random (fake) friends to increase the
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pool of available nodes) and make then send requests to other nodes, the
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response is then relayed back to us and compared to how the node should have
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behaved. If the node is found to be behaving correctly, it is set as trusted.
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Only trusted nodes are sent in send node packets, that is unless the exact node
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being queried for in the getnode packet is present, it will be sent in the
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sendnode packet even if it is not trusted.
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The hypothesis is that if to be part of the network nodes have to behave
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correctly it should prevent disruption from nodes that behave incorrectly.
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(This idea is currently being implemented in the harden branch.)
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...
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