November 17, 2011

Schick WiFi Communication

An Installer’s Guide

(c) 2011 SCHICK TECHNOLOGIES, INC.

ALL RIGHTS RESERVED

INTRODUCTION When installing Schick WiFi at a customer site, it may be beneficial to know which IP addresses and ports are used by the Schick WiFi system. This information is particularly relevant if the customer’s firewall prevents normal operation of the Schick WiFi system. As a guide, this document provides IP address and port information on the following page, as part of a short description about Schick WiFi TCP/IP communication.

ACRONYMS The following acronyms are used in this document: • UDP: User Datagram Protocol • SSDP: Simple Service Discovery Protocol • UPnP: Universal Plug and Play.

SCHICK WIFI There are two distinct aspects of TCP/IP communication in Schick WiFi: COMMUNICATION • Discovery - used by the Schick WiFi Interface and Wireless Monitor to announce the presence of a Schick WiFi Interface on the network and to allow the monitor to display a list of Schick WiFi Interfaces on the network. • Host Protocol - used to pair a Schick WiFi Interface to an individual worksta- tion. Once paired, the workstation and Schick WiFi Interface communicate exclusively through the Schick WiFi Host Protocol.

Discovery. The Discovery mechanism uses a technique called SSDP to broadcast UDP packets over the network. Specifically, the Schick WiFi system employs the standard UPnP protocol to perform the discovery mechanism. (Note: SSDP is the discovery tech- nique that the UPnP standard uses.) Any device listening for UPnP traffic on the net- work can process these messages and determine the presence (or absence) of a Schick WiFi device. The information sent in an SSDP discovery message is somewhat limited, but it provides at least the IP address of the Schick WiFi Interface.

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In addition to SSDP traffic, Schick WiFi also uses a feature in the UPnP standard called Multicast Eventing. This feature allows the Schick WiFi Interface to send its custom set- tings such as serial number, connected sensor, battery strength, signal strength, etc. over the entire network. The Wireless Monitor listens for both SSDP and Multicast Event traffic. Without the Multicast event information, the wireless monitor would have noth- ing to display.

For the UPnP mechanism to successfully allow Schick WiFi Interfaces to appear in the Wireless Monitor, the following traffic must be permitted to travel through the network:

TABLE 1. UPnP Broadcasting

Purpose IP Address Port Protocol SSDP Discovery 239.255.255.250 1900 UDP Multicast Events 239.255.255.246 7900 UDP

Note that both addresses are IP Multicast addresses, meaning that they do not corre- spond to a specific device on the network; rather, they indicate that the packet must be sent to all devices on the network that are part of a particular multicast group.

A redundant mechanism for Discovery, using UDP Broadcasting rather than the UPnP multicasting, is also implemented. This alternative opens a single port and may be use- ful in sites where UPnP cannot be modified or is not available.

TABLE 2. UDP Broadcasting

Purpose IP Address Port Protocol Broadcast Discovery 255.255.255.255 55005 UDP

At least one of the methods described above, UPnP or UDP Broadcasting, must be sup- ported on the customer’s network.

Host Protocol. When customers are ready to use the Schick WiFi Interface for imaging, they initiate a process called pairing. This process establishes a direct TCP/IP connec- tion between the workstation and the Schick WiFi Interface. When TCP/IP is used for direct communication, one device must be listening for an incoming connection (the server) and another device must initiate the connection request (the client).

The Schick WiFi Host Protocol specifies that the Schick WiFi Interface act as the server for establishing this connection; therefore, the Schick WiFi Interface is listening for incoming connection requests. This functions as designed since attempting to use the workstation as a server would result in more security risks and may require further inter- vention with Windows operating systems and firewalls. The Schick WiFi Host Protocol listens for incoming connections on two different ports: • One connection is used for messages sent from the workstation to the Schick WiFi Interface • A second connection is used for messages in the reverse direction from the Schick WiFi Interface to the workstation.

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For the Schick WiFi Host Protocol to allow pairing and image acquisition, the following ports must be opened for traffic between the Schick WiFi Interface and workstation:

TABLE 3. Host Protocol Ports

Purpose IP Address Port Protocol Forward Channel Schick WiFi 55000 TCP Interface IP Address Reverse Channel Schick WiFi 55001 TCP Interface IP Address

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