Network Operating System also referred to as the Dialoguer, is the software that runs on a server and enables the server to manage data, users, groups, security, applications, and other networking functions. The network operating system is designed to allow shared file and printer access among multiple computers in a network, typically a local area network (LAN), a private network or to other networks. The most popular network operating systems are Microsoft Windows Server 2003, Microsoft Windows Server 2008, UNIX, Linux, Mac OS X, Novell NetWare, and BSD.
Use in Routers 
- JUNOS, used in routers and switches from Juniper Networks,
- Cisco IOS (formerly "Cisco Internetwork Operating System").
- TiMOS, used in routers from Alcatel-Lucent
- Huawei VRP (Versatile Routing Platform), used in routers from Huawei
- MikroTik RouterOS™ (is a router operating system and software which turns a regular Intel PC or MikroTik RouterBOARD™ hardware into a dedicated router.)
- ZyNOS, used in network devices made by ZyXEL.
- ExtremeXOS, used in network devices made by Extreme Networks. Also called EXOS.
In a peer-to-peer network operating system users are allowed to share resources and files located on their computers and access shared resources from others. This system is not based with having a file server or centralized management source. A peer-to-peer network sets all connected computers equal; they all share the same abilities to use resources available on the network.
- Ease of setup
- Less hardware needed, no server needs to be purchased.
- No central location for storage.
- Lack of security that a client/server type offers.
Client/server network operating systems allow the network to centralize functions and applications in one or more dedicated file servers. The server is the center of the system, allowing access to resources and instituting security. The network operating system provides the mechanism to integrate all the components on a network to allow multiple users to simultaneously share the same resources regardless of physical location.
- Centralized servers are more stable.
- Security is provided through the server.
- New technology and hardware can be easily integrated into the system.
- Servers are able to be accessed remotely from different locations and types of systems.
- Cost of buying and running a server are high.
- Dependence on a central location for operation.
- Requires regular maintenance and updates.
Security Issues Involved in using a Client/Server Network 
In a client/server network security issues may evolve at three different locations: the client, the network, and the server. All three points need to be monitored for unauthorized activity and need to be secured against hackers or eavesdroppers.
The client is the end user of the network and needs to be secured the most. The client end usually exposes data through the screen of the computer. Client connections to server should be secured through passwords and upon leaving their workstations clients should make sure that their connection to the server is securely cut off in order to make sure that no hackers or intruders are able to reach the server data. Not only securing the workstations connection to the server is important but also securing the files on the workstation (client) is important as it ensures that no hackers are able to reach the system. Another possibility is that of introducing a virus or running unauthorized software on the client workstation thus threatening the entire information bank at the server (Exforsys Inc., 2007).
The users themselves could also be a security threat if they purposely leave their IDs logged in or use easy IDs and passwords to enable hacking. Users may also be sharing their passwords in order to give the hackers access to confidential data (Wilson, Lin, & Craske, 1999). This can be overcome by giving passwords to each client and regularly asking clients to change their passwords. Also passwords should be checked for guessability and for their strength and uniqueness.
The network allows transmission of data from the clients to the server. There are several points on the network where a hacker could eavesdrop or steal important packets of information. These packets may contain important confidential data such as passwords or company details. It is important that these networks are secured properly to keep unauthorized professionals away from all the data stored on the server. This can be done by encrypting important data being sent on the network. However, encryption may not be the only possible way of protecting networks as hackers can work their way around encryption. Another method could be conducting security audits regularly and ensuring identification and authorisation of individuals at all points along the network. This should discourage potential hackers (Wilson, Lin, & Craske, 1999). Making the entire environment difficult to impersonate also makes sure that the clients are reaching the true files and applications on the server and that the server is providing information to authorized personnel only.
The server can be secured by placing all the data in a secure, centralized location that is protected through permitting access to authorized personnel only. Virus protection should also be available on server computers as vast amounts of data can be infected. Regular upgrades should be provided to the servers as the software and the applications need to be updated. Even the entire body of data on a server could be encrypted in order to make sure that reaching the data would require excessive time and effort (Wilson, Lin, & Craske, 1999).
See also 
- Al-Shawakfa, Emad; Evens, Martha (2001). "The Dialoguer: An Interactive Bilingual Interface to a Network Operating System.", Expert Systems Vol. 18 Issue 3, p131, 19p, Retrieved 5/7/2011.
- Dean, Tamara (2009). "Network Operating Systems", Network+ Guide to Networks, 421(483).
- Winkelman, Dr. Roy (2009). "Chapter 6: Software", An Educator's Guide to School Networks, 6.
- Davis, Ziff (2011). "network operating system", PCmag.comRetrieved 5/7/2011.
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