Question

Let's say you have reconfigured a network using brand-new routers. You are not certain if you configured the most appropriate default gateway settings for your hosts. How can you use an analyzer to determine if your default gateway settings are appropriate?

Answer 1

It is really important that one must analyze that the network he/she has built up using brand-new routers is having appropriate settings. For this purpose, one can use an analyzer like "Wireshark".

Wireshark is nothing but a packet analyzer that is available as an open source.Wireshark works on basis of capturing packets, filtering them and inspecting them.

Capturing Packets: First of all download and install Wireshark then one can launch it. After this click the name of an interface under Interface List to start capturing packets on that interface.As soon as we click the interface’s name, we will see the packets start to appear in real time. Wireshark captures each packet sent to or from our system. Packets are highlighted in green, blue, and black.By default, green is TCP traffic, dark blue is DNS traffic, light blue is UDP traffic, and black identifies TCP packets with problems.

Filtering Packets: The basic way to apply a filter is by typing it into the filter box at the top of the window and clicking Apply.

Inspecting Packets: We need to click a packet to select it and we can view its details.

We can tie up Wireshark at the mirror port and look for ARP requests for the routers.