Server Message Block (SMB) is an application-level clientserver protocol that enables sharing resources - files, printers and serial ports between users on the network. Microsoft version of SMB running over TCP/IP is called Common Internet File System (CIFS) and is used by Microsoft Windows OS to provide access to shared Windows resources such as files and printers. Due to enormous popularity of Windows OS, CIFS protocol traffic has become extremely common in modern TCP/IP networks. On internal LANs or Intranets that are often comprised of hundreds or thousands of personal workstations running Microsoft Windows, CIFS protocol can account for majority of traffic passed between hosts.