Mayank Sharma advice is technically right but might not work in most of the environments because organizations/individuals use network switches nowadays which route data only to the intended recipient. Wireshark would work only where network hubs are used which broadcast the traffic to every node in the network.
In order to sniff traffic in switched environments you have to perform MITM (Man In The Midddle) through ARP poisoning. Once you perform MITM, you will be able to sniff data of the other nodes in a switch environment. I don't know if you are authorized to perform sniffing or MITM on the other machines so make sure you have prior approval.
In order to perform MITM you can use many open and closed source tools. Cain and Abel and Ettercap are two tools that are very easy to perform MITM. Cain and Abel is only for Windows platform while Ethercap works fine on both Windows and Linux.