How do you monitor incoming and outgoing data in a network?

[code?]

Ok, I've seen this app for a game that can read all the data and messages that come in and go out. It also detects who is connected to you, and their IP.

It also has an option for selecting a NIC and other stuff like.

OS: Microsoft Windows XP Professional Service Pack 2 (Build 2600)
WinPCap Version: 3.1.0.27
WinPCap is running properly.

Local IP addresses:
172.16.1.37

Available adapters:
Generic dialup adapter
Intel(R) PRO/1000 PL Network Connection (Microsoft's Packet Scheduler)

Listening for traffic on
Intel(R) PRO/1000 PL Network Connection (Microsoft's Packet Scheduler) for 00:01:49

Filtering traffic for TCP or PPPoE.

Traffic occurrence:
No PPPoE packets received yet.
TCP packets received.
No incoming WC3 packets received yet.
No outgoing WC3 packets received yet.

Some TCP packets have been received but no traffic.

So, how do I monitor packets?

[messycan]

They use the WinPCap driver/library to monitor packets. You must have a compatible enet/wireless card in order to do this.

Search for C# WinPCap wrappers on google, and I bet you will find lots of examples.

[STLDude]

WireShark (http://www.wireshark.org/)

[Talikag]

WireShark (http://www.wireshark.org/)
Or other packet sniffer