Re: icmp traceroute
Re: icmp traceroute
- Subject: Re: icmp traceroute
- From: "Peter Sichel" <email@hidden>
- Date: Sun, 27 Aug 2006 14:45:23 -0400
On 8/27/06, Dalton Hamilton wrote:
>Hi Josh and Peter -
>Thanks to both of you for pointing out the IP header is copied in
>the reply.
You actually get the IP header plus the first 64-bits of whatever
follows the IP header from the "triggering" datagram.
>Therefore, I've been trying to figure a way to set the ip_id in the
>IP Header.
You can't normally do this. The ip_id is used to uniquely identify
fragments needing to be reassembled so must be unique for each datagram
generated.
>Again, setting
>the icmp_id and icmp_seq numbers will do no good for EXPIRED packets
>because there will be no ICMP header in the returned IP header.
That's not quite correct. You get the first 64-bits of the icmp header.
>However, I found an application called MTR. I downloaded the code
>and looked at it. Here is what it does and it acts as the EXPIRED
>response includes the original ICMP header immediately after the
>returned IP Header.
That's correct. You can read about this in "TCP/IP Illustrated, Vol 1"
by W. Richard Stevens, or "Internetworking with TCP/IP" by Douglas Comer.
Kind Regards,
- Peter
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