Re: [tor-bugs] #5934 [Tor Relay]: Tor relay denial of service

["Tor Bug Tracker & Wiki" <torproject-admin@xxxxxxxxxxxxxx>]

#5934: Tor relay denial of service
-----------------------+----------------------------------------------------
 Reporter:  runa       |          Owner:     
     Type:  task       |         Status:  new
 Priority:  normal     |      Milestone:     
Component:  Tor Relay  |        Version:     
 Keywords:             |         Parent:     
   Points:             |   Actualpoints:     
-----------------------+----------------------------------------------------

Comment(by asn):

 Not sure what's the idea here.

 It seems to me that it simply reaches `command_process_cell()` and
 triggers:
 {{{
   /* Reject all but VERSIONS and NETINFO when handshaking. */
   /* (VERSIONS should actually be impossible; it's variable-length.) */
   if (handshaking && cell->command != CELL_VERSIONS &&
       cell->command != CELL_NETINFO) {
     log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
            "Received unexpected cell command %d in state %s; ignoring
 it.",
            (int)cell->command,
            conn_state_to_string(CONN_TYPE_OR,conn->_base.state));
     return;
   }
 }}}
 repeatedly (he is sending `PADDING` cells). I don't see anything CPU-
 exciting happening there.

 I tested it in a remote relay of mine and I didn't notice any kind of high
 CPU activity.

 Maybe he only tried this on localhost and he was getting DoSed by his
 python process.

-- 
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/5934#comment:2>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online
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