KruemelMonsta (also KrümelMonsta) is a RubyPcap based network traffic filter based on connection assoziation. Basically it tries to detect which type of connection it is, if it knows the type it works with the data and a specific way if it doesnt know what it, it will just be ignored.
The different connection types are modules which can be easily extended.
Next to the basic functionality it also is able to spawn a proxy server which includes the gathered (and filtered) cookies. So you can just start up your browser, configure your proxy settings and surf with the very same cookies a other client on your network has.
Note: This really could use an update to a more recent Pcap implementation (also a few other things). But it works for now.