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b0e92634d8
This defense will cause Cisco, Juniper, Fortinet, and other routers operating in the default configuration to collapse netflow records that would normally be split due to the 15 second flow idle timeout. Collapsing these records should greatly reduce the utility of default netflow data for correlation attacks, since all client-side records should become 30 minute chunks of total bytes sent/received, rather than creating multiple separate records for every webpage load/ssh command interaction/XMPP chat/whatever else happens to be inactive for more than 15 seconds. The defense adds consensus parameters to govern the range of timeout values for sending padding packets, as well as for keeping connections open. The defense only sends padding when connections are otherwise inactive, and it does not pad connections used solely for directory traffic at all. By default it also doesn't pad inter-relay connections. Statistics on the total padding in the last 24 hours are exported to the extra-info descriptors.
18 lines
533 B
Plaintext
18 lines
533 B
Plaintext
const CHANNELPADDING_COMMAND_STOP = 1;
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const CHANNELPADDING_COMMAND_START = 2;
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/* This command tells the relay to alter its min and max netflow
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timeout range values, and send padding at that rate (resuming
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if stopped). */
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struct channelpadding_negotiate {
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u8 version IN [0];
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u8 command IN [CHANNELPADDING_COMMAND_START, CHANNELPADDING_COMMAND_STOP];
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/* Min must not be lower than the current consensus parameter
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nf_ito_low. */
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u16 ito_low_ms;
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/* Max must not be lower than ito_low_ms */
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u16 ito_high_ms;
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};
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