Traceroute supporting ICMP ECHO

Joe Marcus Clarke marcus at
Wed May 12 12:38:00 PDT 2004

On Wed, 2004-05-12 at 15:29, Clint Olsen wrote:
> Hi:
> I'm using 4.7p1 here, and I've had all sorts of fun on occasion with
> traceroute and my various firewall/routers.  The default traceroute will
> not work since UDP traffic is apparently blocked on the return.  Opening up
> port ranges on my router just doesn't seem right.  However, Linux
> traceroute has a -I option (I think Windows tracert uses ICMP ECHO by
> default) which allows it to work through a home firewall router.  The
> FreeBSD port for mtr also works.

Someone already pointed out you can use different protocols with
traceroute.  However, you wouldn't need to open a range of UDP ports to
get it working.  traceroute uses a "well-known" UDP port by default:
33434.  This is also changeable using the -p option (very rarely, some
destinations may be listening on UDP port 33434, and thus they would not
send the final PORT_UNREACHABLE ICMP reply).


> Is there anyone who has considered adding this capability to FreeBSD?
> Thanks,
> -Clint
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