{{Unreferenced, date=December 2009 An Internet Locator Server (abbreviated ILS) is a server that acts as a directory for

Microsoft NetMeeting Microsoft NetMeeting is a discontinued VoIP and multi-point videoconferencing client included in many versions of Microsoft Windows (from Windows 95 OSR2 to Windows Vista). It uses the H.323 protocol for videoconferencing, and is interoperable wit ...

clients. An ILS is not necessary within a

local area network A local area network (LAN) is a computer network that interconnects computers within a limited area such as a residence, school, laboratory, university campus or office building. By contrast, a wide area network (WAN) not only covers a larger ...

and some

wide area network A wide area network (WAN) is a telecommunications network that extends over a large geographic area. Wide area networks are often established with leased telecommunication circuits. Businesses, as well as schools and government entities, us ...

s in the

Internet The Internet (or internet) is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a '' network of networks'' that consists of private, pub ...

because one participant can type in the

IP address An Internet Protocol address (IP address) is a numerical label such as that is connected to a computer network that uses the Internet Protocol for communication.. Updated by . An IP address serves two main functions: network interface ident ...

of the other participant's host and call them directly. An ILS becomes necessary when one participant is trying to contact a host who has a

private IP address In Internet networking, a private network is a computer network that uses a private address space of IP addresses. These addresses are commonly used for local area networks (LANs) in residential, office, and enterprise environments. Both the IP ...

internal to a local area network that is inaccessible to the outside world, or when the host is blocked by a

firewall Firewall may refer to: * Firewall (computing), a technological barrier designed to prevent unauthorized or unwanted communications between computer networks or hosts * Firewall (construction), a barrier inside a building, designed to limit the spr ...

. An ILS is also useful when a participant has a different IP address during each session, e.g., assigned by the

Dynamic Host Configuration Protocol The Dynamic Host Configuration Protocol (DHCP) is a network management protocol used on Internet Protocol (IP) networks for automatically assigning IP addresses and other communication parameters to devices connected to the network using a cli ...

. There are two main approaches to using Internet Location Servers: use a public server on the Internet, or run and use a private server.

Private Internet Location Server

The machine running an Internet Location Server must have a public IP address. If the network running an Internet Location Server has a firewall, it is usually necessary to run the server in the

demilitarized zone A demilitarized zone (DMZ or DZ) is an area in which treaties or agreements between nations, military powers or contending groups forbid military installations, activities, or personnel. A DZ often lies along an established frontier or bounda ...

of the network.

Microsoft Windows Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for serv ...

includes an Internet Location Server. It can be installed in the Control Panel using Add/Remove Windows Components, under "Networking Services" (Site Server ILS Services). The Internet Location Server (ILS) included in

Microsoft Windows 2000 Windows 2000 is a major release of the Windows NT operating system developed by Microsoft and oriented towards businesses. It was the direct successor to Windows NT 4.0, and was released to manufacturing on December 15, 1999, and was officiall ...

offers service on port 1002, while the latest version of NetMeeting requests service from port 389. The choice of 1002 was to avoid conflict with Windows 2000's

domain controller A domain controller (DC) is a server computer that responds to security authentication requests within a computer network domain. It is a network server that is responsible for allowing host access to domain resources. It authenticates users, sto ...

s, which use LDAP and Active Directory on port 389, as well as

Microsoft Exchange Server Microsoft Exchange Server is a mail server and calendaring server developed by Microsoft. It runs exclusively on Windows Server operating systems. The first version was called Exchange Server 4.0, to position it as the successor to the related ...

2000, which uses port 389. If the server is running neither Active Directory nor Microsoft Exchange Server, the Internet Location Server's port can be changed to 389 using the following command at a command prompt: ILSCFG ervername/port 389

Additional firewall issues

Internet Location Servers do not address two other issues with using NetMeeting behind a firewall. First, although a participant can join the directory from an external IP address, the participant cannot join a meeting unless the internal host manually adds the participant to the meeting from the directory. Second, while this approach is fine for data conferencing, audio or video conferencing requires opening of a wide range of ports on the firewall. In this case, it may be desirable to use a gateway.

Private Internet Location Server

Additional firewall issues

See also