It watches for traffic containing the IP address of the machine on which I created this blog, which is 10.1.10.129. Selections and editing appearance is shown in figure 3:Īs an example, I have created a filter called My machine. You can also edit the existing Capture Filter choices when clicking that button. Or you can select the Capture Filter button and choose from the precompiled list.

If you already know your filter topic, you can just type in the area noted by the red box. Once you click that, you will see (with some of the window omitted) what is shown in figure 2: It is easily accessed by clicking the icon at the top left of the main window. The type of filter controls what type of traffic is captured, and disregards all non-matching traffic. The first type of filter we will discuss is the capture filter.

I just want to show the difference in a more visual way, ‘cause some people learn better that way! For my screenshots, I will be using what is (at the time of this writing) the latest version, which is 1.12.3. Today I will discuss two ways to filter in Wireshark: display filter and capture filter.ĭon’t get me wrong – Wireshark is well documented. When running a full-bore packet capture session, you may find that data are accumulating quite rapidly and likely you are obtaining much more than you want to look at. Since we don’t live in a perfect world, I wanted to demonstrate a little piece of the freely downloadable network packet sniffer called Wireshark. The value 22 (0x16 in hexadecimal) has been defined as being “Handshake” content.Īs a consequence, tcp & 0xf0) > 2)] = 0x16 captures every packet having the first byte after the TCP header set to 0x16.In a perfect world, there would be no need to monitor network traffic looking for interlopers. The first byte of a TLS packet define the content type. The offset, once multiplied by 4 gives the byte count of the TCP header, meaning ((tcp & 0xf0) > 2) provides the size of the TCP header.

Tcp means capturing the 13th byte of the tcp packet, corresponding to first half being the offset, second half being reserved. Tcp & 0xf0) > 2)] = 0x16: a bit more tricky, let’s detail this below

Tcp port 443: I suppose this is the port your server is listening on, change it if you need Tcpdump -ni eth0 “tcp port 443 and (tcp & 0xf0) > 2)] = 0x16)”Įth0: is my network interface, change it if you need

Wireshark port filter