Mongodb/Unifi, "DSACK update: -245946829..-245946682, rcv_nxt: 4049020614" spam

nerozero

nerozero

Hello,

Not sure in which thread should I post this, I will try my best here...

After recent update (January 2nd) The Unifi module spamming messages and dmesg with following messages: (se messages under spoiler)
The source of this messages is unifi or mongodb (imho)....

Code: 
cat /var/log/messages | grep DSACK
Jan 24 18:40:00 nz kernel: DSACK update: -76523026..-76522865, rcv_nxt: 4218444431
Jan 24 18:40:00 nz kernel: DSACK update: -76522865..-76522694, rcv_nxt: 4218444602
Jan 24 18:40:00 nz kernel: DSACK update: -76522694..-76522533, rcv_nxt: 4218444763
Jan 24 18:40:00 nz kernel: DSACK update: -76522533..-76522372, rcv_nxt: 4218444924
Jan 24 18:40:00 nz kernel: DSACK update: -76522372..-76522211, rcv_nxt: 4218445085
Jan 24 18:40:00 nz kernel: DSACK update: -76522211..-76522048, rcv_nxt: 4218445248
Jan 24 18:40:00 nz kernel: DSACK update: -76522048..-76521885, rcv_nxt: 4218445411
Jan 24 18:40:00 nz kernel: DSACK update: -1717928016..-1717927840, rcv_nxt: 2577039456
Jan 24 18:40:00 nz kernel: DSACK update: -1717927840..-1717927657, rcv_nxt: 2577039639
Jan 24 18:40:02 nz kernel: DSACK update: -245951574..-245951413, rcv_nxt: 4049015883
Jan 24 18:40:02 nz kernel: DSACK update: -1717927510..-1717927349, rcv_nxt: 2577039947
Jan 24 18:40:02 nz kernel: DSACK update: -1717927349..-1717927211, rcv_nxt: 2577040085
Jan 24 18:40:02 nz kernel: DSACK update: -1717927211..-1717927059, rcv_nxt: 2577040237
Jan 24 18:40:07 nz kernel: DSACK update: -1717926912..-1717926751, rcv_nxt: 2577040545
Jan 24 18:40:07 nz kernel: DSACK update: -245951266..-245951105, rcv_nxt: 4049016191
Jan 24 18:40:07 nz kernel: DSACK update: -1717926751..-1717926585, rcv_nxt: 2577040711
Jan 24 18:40:07 nz kernel: DSACK update: -245951105..-245950930, rcv_nxt: 4049016366
Jan 24 18:40:07 nz kernel: DSACK update: -245950930..-245950755, rcv_nxt: 4049016541
Jan 24 18:40:07 nz kernel: DSACK update: -1717926585..-1717926419, rcv_nxt: 2577040877
Jan 24 18:40:07 nz kernel: DSACK update: -245950755..-245950589, rcv_nxt: 4049016707
Jan 24 18:40:07 nz kernel: DSACK update: -245950589..-245950423, rcv_nxt: 4049016873
Jan 24 18:40:07 nz kernel: DSACK update: -245950423..-245950257, rcv_nxt: 4049017039
Jan 24 18:40:07 nz kernel: DSACK update: -245950257..-245950091, rcv_nxt: 4049017205
Jan 24 18:40:11 nz kernel: DSACK update: -245949498..-245949322, rcv_nxt: 4049017974
Jan 24 18:40:11 nz kernel: DSACK update: -245949322..-245949139, rcv_nxt: 4049018157
Jan 24 18:40:24 nz kernel: DSACK update: -245948546..-245948370, rcv_nxt: 4049018926
Jan 24 18:40:24 nz kernel: DSACK update: -245948370..-245948187, rcv_nxt: 4049019109
Jan 24 18:40:37 nz kernel: DSACK update: -245947594..-245947418, rcv_nxt: 4049019878
Jan 24 18:40:37 nz kernel: DSACK update: -245947418..-245947235, rcv_nxt: 4049020061
Jan 24 18:41:00 nz kernel: DSACK update: 1527366755..1527366814, rcv_nxt: 1527366814
Jan 24 18:41:01 nz kernel: DSACK update: 1527366876..1527366934, rcv_nxt: 1527366934
Jan 24 18:41:04 nz kernel: DSACK update: -245946924..-245946829, rcv_nxt: 4049020467
Jan 24 18:41:04 nz kernel: DSACK update: -1717926283..-1717926188, rcv_nxt: 2577041108
Jan 24 18:41:04 nz kernel: DSACK update: -245946829..-245946682, rcv_nxt: 4049020614
Jan 24 18:41:04 nz kernel: DSACK update: -1717926188..-1717926041, rcv_nxt: 2577041255
Jan 24 18:41:04 nz kernel: DSACK update: -1717925880..-1717925742, rcv_nxt: 2577041554
Jan 24 18:41:04 nz kernel: DSACK update: -1717925742..-1717925590, rcv_nxt: 2577041706

Is there a solution for that ?
 
Last edited by a moderator:
Update.
after some research I have found this code:
C: 
// Line 169, file: /usr/src/sys/netinet/tcp_sack.c
if (tp->t_inpcb->inp_socket->so_options & SO_DEBUG) {
                log(LOG_DEBUG, "\nDSACK update: %d..%d, rcv_nxt: %u\n",
                rcv_start, rcv_end, tp->rcv_nxt);
        }

so this is probably not the issue of the port but someone forget to turn off DEBUG in FreeBSD kernel ... (I have updated it too)...
forget to describe version:
uname -a: 12.1-RELEASE-p1 GENERIC amd64
 
Shouldn't this be logged with a debug level in any case? As /var/log/messages only logs info or higher (by default) it shouldn't even appear? Or am I misunderstanding LOG_DEBUG in this context?

Edit: Oh, wait. kern.debug ends up in messages too. Quick and dirty fix would be to change it to kern.info. You could set it until that bit of code is removed.
 
Should be 3.6, as that's what UniFi depends on. I downloaded the source to .17 and .14 but I couldn't find any instances of SO_DEBUG or setsockopt in the diff.
 
I've upgraded one of my mongodb instance to 4.0 and I don't have the dsack message anymore (not sure if it's related though).
 
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