[tor-relays] Guard node suddenly sending twice what it receives

[Logforme]

>Check the logs, but they won't tell you much, and that's deliberate.
>
So I checked the tor log.

First part is before the "weirdness":
Dec 20 16:00:08.000 [notice] Heartbeat: Tor's uptime is 4 days 23:59 
hours, with 36191 circuits open. I've sent 3686.92 GB and received 
3646.75 GB.
Dec 20 16:00:08.000 [notice] Circuit handshake stats since last time: 
160437/160437 TAP, 5003782/5003782 NTor.
Dec 20 16:00:08.000 [notice] Since startup, we have initiated 0 v1 
connections, 0 v2 connections, 1 v3 connections, and 102511 v4 
connections; and received 2151 v1 connections, 29819 v2 connections, 
46331 v3 connections, and 683484 v4 connections.

Next time during the weirdness:
Dec 20 22:00:08.000 [notice] Heartbeat: Tor's uptime is 5 days 5:59 
hours, with 233634 circuits open. I've sent 3908.13 GB and received 
3832.44 GB.
Dec 20 22:00:08.000 [notice] Circuit handshake stats since last time: 
564576/564576 TAP, 18285622/18285622 NTor.
Dec 20 22:00:08.000 [notice] Since startup, we have initiated 0 v1 
connections, 0 v2 connections, 1 v3 connections, and 107666 v4 
connections; and received 2309 v1 connections, 31585 v2 connections, 
49188 v3 connections, and 711324 v4 connections.

Note that the number of circuits have gone up from a relatively normal 
number, 36191, to a massive 233634. Definitely not normal.  And this is 
with my connection limits in place in the iptables.

The tor process now uses about twice as much CPU as normally.

I think the attacker has found a new way "in".