Messages in this thread | | | Subject | Re: udp traceroute dropping packets | From | Philippe Troin <> | Date | 15 Apr 2004 20:15:10 -0700 |
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Russell Miller <rmiller@duskglow.com> writes:
> -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > I came across this archived linux-kernel message: > > http://www.uwsg.iu.edu/hypermail/linux/net/0007.2/0111.html > > I am having the exact same problem as is outlined there, from a post three > years ago. Here's a summary: > > "I think I've found a bug in UDP/ICMP code in the kernel using > traceroute. > > To reproduce: Launch traceroute -n to some Linux system nearby > really quickly 3 times in the row; localhost won't work, it has to go > through network. Quick response is crucial. I used systems w/ in > the same physical network and a few routers between (still < 5 ms > response). > > The effect: On third traceroute (or perhaps second/first, if you're quick > enough), ICMP port unreachable will not be sent to the UDP datagram. " > > I reproduced this on a redhat 8.0 machine running kernel 2.4.23. > Changing to the -I option of traceroute (to use ICMP) works > flawlessly. I'll be glad to provide more information if you need > it. Please CC, as I'm not subscribed.
You're probably hitting the ICMP rate limit.
Play with /proc/sys/net/ipv4/icmp_rate*.
- increase /proc/sys/net/ipv4/icmp_ratelimit
or
- clear bit 3 in /proc/sys/net/ipv4/icmp_ratemask
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