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

on my trace I have

DHCP Request
DHCP ACK
DHCP Request

I don't understand what triggers the second request. the difference between the two request packets is the packet subtype first request packet flags: .... ..01 = DS status: Frame from STA to DS via an AP (To DS: 1 From DS: 0) (0x01) second request packet flags: .... ..10 = DS status: Frame from DS to a STA via AP(To DS: 0 From DS: 1) (0x02)

anyone can help me to figure out whats going on?

asked 10 Oct '11, 05:16

ddayan's gravatar image

ddayan
41151720
accept rate: 0%

edited 10 Oct '11, 05:24


On your wireless lan, all traffic within the same subnet is sent to the AP first and then from the AP to the destination. Depending on the physical location of the capturing device compared to the source, the AP and the destination you will see some or all of the packets.

I suspect that the AP is also the DHCP server and that it responds to the DHCP request. The second Request is most probably due to the fact that it was a broadcast packet so the AP needs to send it to all systems too.

permanent link

answered 10 Oct '11, 06:24

SYN-bit's gravatar image

SYN-bit ♦♦
17.1k957245
accept rate: 20%

Makes sense, right now i'm using a simple topology where the AP is the DHCP server and the client is also the capturing device. thanks!

(10 Oct '11, 06:31) ddayan

I think you will find the first request is the "DHCP Discover", where your client doesn't know of any DHCP servers. Once it sees a response, the ACK, it can then send a proper "DHCP Request". This is still a broadcast, but it will contain a non-zero entry in the the Server IP address field indicating a particular server it would like a DHCP Offer from.

permanent link

answered 10 Oct '11, 05:26

martyvis's gravatar image

martyvis
8911525
accept rate: 7%

How come theres no 2nd ACK packet? Also in both request packets the bootp protocol info is the same

(10 Oct '11, 05:43) ddayan
Your answer
toggle preview

Follow this question

By Email:

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

By RSS:

Answers

Answers and Comments

Markdown Basics

  • *italic* or _italic_
  • **bold** or __bold__
  • link:[text](http://url.com/ "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:

×76
×44
×7

question asked: 10 Oct '11, 05:16

question was seen: 11,863 times

last updated: 10 Oct '11, 06:31

p​o​w​e​r​e​d by O​S​Q​A