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Netflow record collapsing defense.

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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.
This commit is contained in:
Mike Perry
2016-09-06 11:35:53 -07:00
committed by Nick Mathewson
parent 515e1f663a
commit b0e92634d8
30 changed files with 2488 additions and 18 deletions
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src/or/command.c
+18 -4
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@@ -328,8 +328,16 @@ command_process_create_cell(cell_t *cell, channel_t *chan)
if (create_cell->handshake_type != ONION_HANDSHAKE_TYPE_FAST) {
/* hand it off to the cpuworkers, and then return. */
if (connection_or_digest_is_known_relay(chan->identity_digest))
if (connection_or_digest_is_known_relay(chan->identity_digest)) {
rep_hist_note_circuit_handshake_requested(create_cell->handshake_type);
// Needed for chutney: Sometimes relays aren't in the consensus yet, and
// get marked as clients. This resets their channels once they appear.
// Probably useful for normal operation wrt relay flapping, too.
chan->is_client = 0;
} else {
channel_mark_client(chan);
}
if (assign_onionskin_to_cpuworker(circ, create_cell) < 0) {
log_debug(LD_GENERAL,"Failed to hand off onionskin. Closing.");
circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_RESOURCELIMIT);
@@ -344,9 +352,15 @@ command_process_create_cell(cell_t *cell, channel_t *chan)
int len;
created_cell_t created_cell;
/* Make sure we never try to use the OR connection on which we
* received this cell to satisfy an EXTEND request, */
channel_mark_client(chan);
/* If this is a create_fast, this might be a client. Let's check. */
if (connection_or_digest_is_known_relay(chan->identity_digest)) {
// Needed for chutney: Sometimes relays aren't in the consensus yet, and
// get marked as clients. This resets their channels once they appear.
// Probably useful for normal operation wrt relay flapping, too.
chan->is_client = 0;
} else {
channel_mark_client(chan);
}
memset(&created_cell, 0, sizeof(created_cell));
len = onion_skin_server_handshake(ONION_HANDSHAKE_TYPE_FAST,