Limiting icmp unreach response fron 348 to 200 packets/sec

Mike Tancsa mike at
Sat Aug 16 01:22:08 UTC 2008

At 09:01 PM 8/15/2008, Erol Akarsu wrote:
>Thanks for helping this.
>Now, I am getting "Limiting icmp unreach response fron 348 to 200 packets/sec"

         These questions are better asked on 
freebsd-questions at  But the above indicates processes are 
hitting your freebsd server on ports where nothing is listenting and 
the FreeBSD box is sending out "port unreachable" messages at a limit 
of 200 per second, but if it were to answer all bogus requests the 
rate would have been 348 per second.

>In which conditions can we get this? does this effect functionality 
>of the system?

other hosts are accessing ports on your server where nothing is listening.

>How can I solve this issue?

sysctl -w net.inet.tcp.blackhole=1
sysctl -w net.inet.udp.blackhole=1

to stop all the port unreachable messages, but ultimately find out 
why your program / application is not listening on that port.


More information about the freebsd-current mailing list