ICMP Messages: Original Datagram Field

Published: 2022-03-12
Last Updated: 2022-03-12 00:51:34 UTC
by Didier Stevens (Version: 1)
0 comment(s)

I received a couple of private messages regarding my diary entry "TShark & Multiple IP Addresses" and video "Video: TShark & Multiple IP Addresses".

That the ICMP packets do not actually contain an IP packet, but just a part of it.

RFC 792 states that the destination unreachable message only contains the IP header and 8 bytes of the TCP header (that would be the source and destination port, and the sequence number):

That is not the case in my example:

The full TCP packet is included, 32 bytes long.

RFC 792 is more than 40 years old, and has been updated several times since.

For example, in RFC 4884, you can find this:

In a nutshell: include as many bytes from the original datagram as possible, without risking fragmentation.

And for a TCP SYN packet, like in my example, that is no problem at all.

 

Didier Stevens
Senior handler
Microsoft MVP
blog.DidierStevens.com

Keywords: icmp unreachable
0 comment(s)

Comments

cwqwqwq
eweew<a href="https://www.seocheckin.com/edu-sites-list/">mashood</a>
WQwqwqwq[url=https://www.seocheckin.com/edu-sites-list/]mashood[/url]
dwqqqwqwq mashood
[https://isc.sans.edu/diary.html](https://isc.sans.edu/diary.html)
[https://isc.sans.edu/diary.html | https://isc.sans.edu/diary.html]
What's this all about ..?
password reveal .
<a hreaf="https://technolytical.com/">the social network</a> is described as follows because they respect your privacy and keep your data secure:

<a hreaf="https://technolytical.com/">the social network</a> is described as follows because they respect your privacy and keep your data secure. The social networks are not interested in collecting data about you. They don't care about what you're doing, or what you like. They don't want to know who you talk to, or where you go.

<a hreaf="https://technolytical.com/">the social network</a> is not interested in collecting data about you. They don't care about what you're doing, or what you like. They don't want to know who you talk to, or where you go. The social networks only collect the minimum amount of information required for the service that they provide. Your personal information is kept private, and is never shared with other companies without your permission
https://thehomestore.com.pk/

Diary Archives