zissou

eliminating ICMP 3 packets when using UDP datagrams

Discussion created by zissou on Feb 15, 2011
Latest reply on Feb 16, 2011 by PrasanthR

Hi,

 

I have noticed that UDP datagrams sent to a linux host will cause that host to send back ICMP type 3

packets saying "destination unreachable" even when you have used bind on the receving host to the

port in question and can see that using /sbin/route. This can play havoc with the sending unit, which in

my case is a BF537 which is very busy.

 

You can see this happen using wireshark or tcpdump.

 

There are some solutions given for that that involve setting things in the proc filesystem but I have not found

that to work for me. Here is what worked on my system:

 

/sbin/iptables -A OUTPUT -p ICMP   --icmp-type 3 -j DROP

 

I spent a long time on this before and actually bought a smart switch to filter these out because I

couldn't figure it out a few years ago.

 

There may be some trick to use in bind but I don't know that. It would be better if that were so in order

to avoid doing something to the host system. But anyway this works. I found it on the internets but I

forgot where and it had to be modified to work anyway.

 

BTW I am using a non blocking recvfrom, which may be part of the problem

 

-Zissou

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