Could anyone suggest a good packet sniffer class for c++? Looking for a easy insertable class I can use in my c++ program, nothing complicated.
You will never be able to intercept network traffic just by inserting a class into your project. Packet capture functionality requires kernel mode support, hence you will at the very least need to have your application require or install libpcap/WinPcap, as Will Dean pointed out.
Most modern Unix-like distributions include libpcap out of the box, in which case you could take a look at this very simple example: http://www.tcpdump.org/pcap.htm
If you're using Windows, you're more or less on your own, although WinPcap programming is extremely similar to libpcap programming (unsurprisingly, since it's a libpcap port to Win32.) The SDK can be found here: http://www.winpcap.org/devel.htm
At any rate, no matter the operating system, you will need root / Administrator access to actually perform a capture. Just using the library to replay or analyze precaptured data doesn't require any special privilege, of course.