I keep getting this message repeated in dmesg:

[215259.269481] [UFW BLOCK] IN=eth0 OUT=
SRC= DST= LEN=36  TOS=0x00 PREC=0x00 
TTL=1 ID=1711 DF PROTO=2

[215270.008461] CPU2: Core temperature above threshold, 
cpu clock throttled (total events = 2376639)

Any idea why?

  • So which message are you asking about? The two messages you've posted are caused by two different events.
    – Kempniu
    Jul 9, 2014 at 4:29
  • They were both repeating in the same message Jul 9, 2014 at 8:00

1 Answer 1


The first message indicates that your host firewall has blocked an outbound packet. ufw status will show your current ruleset; it looks like something on your computer is trying to multicast, but the packets are being blocked. Unless you're having problems elsewhere it's probably nothing to worry about.

The second message speaks for itself! Core temperature above threshold is a scary thing to see, and I would be planning to shut that machine down and check all the fans are working, and that it's not clogged up with dust or cat fur.


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