[ratelimits] can't make qps-scale change effective slip
irwin at princeton.edu
Sun Jan 6 18:39:39 UTC 2013
I'm unable to get qps-scale to change the effective slip.
Or perhaps I'm misunderstanding the behavior of qps-scale.
BIND 9.9.2-P1 with rpz2+rl-9.9.2-P1.patch (05-Jan-2013 version) applied
Solaris 10 SPARC
Sun Workshop Compiler 11.0
I observed an attack from a single IP address consisting of 7200 queries/second
for a name (which does exist) ANY?.
These were nearly all the queries arriving at my authoritative-only server.
I saw the server send approximately 3600 "truncated" responses/second to the queryer.
These were slipped responses, as expected.
That rate made sense to me as I'd let slip default to 2.
Both the named statistics file and packet capture confirmed the query rate and the
slipped response rate.
The normal query rate (for all queries) to this server is 13 queries/second.
I reconfigured to:
I expected the result would be that the ongoing 7200 queries/second attack
would cause effective slip = (60/7200)*2 = 0.016.
So I expected the server would send approximately 7200 * 0.016 = 120 "truncated" responses/second to this queryer.
Instead the server continued to send approximately 3600 "truncated" responses/second to the queryer.
That appears confirmed both by the named statistics file, and my own packet capture.
I don't seem to be able to get qps-scale to change effective slip, or I'm misunderstanding qps-scale.
+++ Statistics Dump +++ (1357496364)
++ Incoming Requests ++
++ Incoming Queries ++
++ Outgoing Queries ++
++ Name Server Statistics ++
866488 IPv4 requests received
866250 requests with EDNS(0) received
10 auth queries rejected
433825 responses sent
432710 truncated responses sent
433562 responses with EDNS(0) sent
651 queries resulted in successful answer
433619 queries resulted in authoritative answer
200 queries resulted in non authoritative answer
200 queries resulted in referral answer
432917 queries resulted in nxrrset
4 queries resulted in SERVFAIL
50 queries resulted in NXDOMAIN
432710 queries dropped
432712 responses dropped for rate limits
432707 responses truncated for rate limits
++ Zone Maintenance Statistics ++
More information about the ratelimits