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

I would like to look for packets sent between to Linux 2.6.32 systems that are coming from the kernel due to sockets that have SO_KEEPALIVE set having been idle long enough to cause keep alive packets to be sent. What filter expression should I use? I'd prefer a capture filter but if only a display filter works I can use that instead. Thanks

asked 23 May '13, 15:06

token's gravatar image

token
6113
accept rate: 0%


You might not be able to see this in the packets themselves unless they have some specific bytes that makes them distinguishable, and the keep-alives I have seen so far are usually normal TCP packets without any payload. The Wireshark TCP expert marks them as keep-alives though because it keeps track of the TCP session. You can filter for them by using the display filter, "tcp.analysis.keep_alive".

permanent link

answered 23 May '13, 15:13

Jasper's gravatar image

Jasper ♦♦
23.8k551284
accept rate: 18%

edited 30 Jun '13, 23:59

cmaynard's gravatar image

cmaynard ♦♦
9.4k1038142

TCP network packets with no data in it and the ACK flag turned on.

permanent link

answered 30 Jun '13, 00:19

Inge%20Eivind%20Henriksen's gravatar image

Inge Eivind ...
111
accept rate: 0%

That'll also see normal ACK-only packets, sent because the machine sending the ACK-only packet has no data to transmit but needs to acknowledge data it received.

(30 Jun '13, 20:10) Guy Harris ♦♦
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:

×184
×154
×8

question asked: 23 May '13, 15:06

question was seen: 22,905 times

last updated: 30 Jun '13, 23:59

p​o​w​e​r​e​d by O​S​Q​A