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altman
Asked: 2012-06-20 19:26:10 +0800 CST

freebsd dmesg has a lot of "Limiting icmp unreach response from 1293 to 200 packets/sec"

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I has a simple freebsd 9.0 machine.But everytime i start my freebsd and use command dmesg. There aren't any hardware information there but full of 

         "Limiting icmp unreach response from 1293 to 200 packets/sec"

there.

Does any one there can tell me why this happen? And how can i erase this ?

networking freebsd icmp

2 Answers

  1. Also you can disable this messages by sysctl:

    sysctl net.inet.tcp.blackhole=2
sysctl net.inet.udp.blackhole=1

    More info in man blackhole

    Add those lines to /etc/sysctl.conf to make those changes persistent.

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  2. Best Answer

    It seems that your machine is being hit by UDP packets which are destined to closed ports. So, it is generating ICMP unreachable responses and this message tells you that the current limit 200 packets/sec has been reached. You need to find the reason of such a traffic. Packet capturing tools like tcpdump/wireshark are very useful to diagnose such problems. You can find the packets received by your machine and who is sending them.

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