This is our old Q&A Site. Please post any new questions and answers at

Hi After IP Fragmentation two times (UDP not TCP ), I get the error Fragment Overlap: True , and then the host does not respond anymore.

Can you tell me please what can cause the fragment overlap in general ?

Thanks alot

asked 13 Oct '17, 08:53

webtuto's gravatar image

accept rate: 0%

Can you upload the PCAP? If you need to sanitize it first, use this tutorial:

(13 Oct '17, 12:40) Jasper ♦♦

Without having looked at the specifics, the theory is that the sending host is chopping up the UDP packet into smaller parts to be able to transport is over the network to the other IP endpoint. For that purpose the IP header contains a payload length and offset, which allows the receiver's IP layer to put all pieces back together, like a jigsaw puzzle, into a complete UDP packet. When the sending host's IP layer miscalculates the offsets and/or lengths, the receiver will have jigsaw pieces that don't fit together, in this case there are overlapping parts. That will raise this error. So the cause is usually found in either the sending host's IP stack or any intervening network device which interacts at the IP layer, eg. NAT's.

permanent link

answered 14 Oct '17, 02:18

Jaap's gravatar image

Jaap ♦
accept rate: 14%

edited 14 Oct '17, 07:01

sindy's gravatar image


Your answer
toggle preview

Follow this question

By Email:

Once you sign in you will be able to subscribe for any updates here



Answers and Comments

Markdown Basics

  • *italic* or _italic_
  • **bold** or __bold__
  • link:[text]( "title")
  • image?![alt text](/path/img.jpg "title")
  • numbered list: 1. Foo 2. Bar
  • to add a line break simply add two spaces to where you would like the new line to be.
  • basic HTML tags are also supported

Question tags:


question asked: 13 Oct '17, 08:53

question was seen: 1,018 times

last updated: 14 Oct '17, 07:01

p​o​w​e​r​e​d by O​S​Q​A