Know the services provided by network systems:

File & Application Services

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Directory Services Account Management

Authentication management

Active Directory

DNS

Communications Services email

Discussion Boards

File Transfer

Remote Access - Mobiles

Remote Desktop

Social Networking

IRC

File Services

Applications Services Authentication

User

Hardware

Databases

Mobile Working

Proxy

Shared Resources

Devices

Storage Space

Web

VOIP

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One of the most important functions of a network operating system is its ability to share resources with other network users. The most common resource that’s shared is the server’s file system. A network server must be able to share some or all of its disk space with other users so that those users can treat the server’s disk space as an extension of their own computer’s disk space.

The Network OS allows the system administrator to determine which portions of the server’s file system to share. Although an entire hard drive can be shared, it is not commonly done. Instead, individual directories or folders are shared. The administrator can control which users are allowed to access each shared folder.

Because file sharing is the reason many network servers exist, network operating systems have more sophisticated disk management features than are found in desktop operating systems. For example, most network operating systems have the ability to manage two or more hard drives as if they were a single drive. In addition, most can create mirrors, which automatically keeps a backup copy of a drive on a second drive. Other benefits include:

The ability to share files or work on the same file by multiple people

The ability to set rights to files

Remote access to files through RDC

Restricted times on files for exams

Undelete options on files and programs

Group allocation of a file3

There are two kinds of authentication that goes on when a user switches on a machine, User and Hardware.

User authentication – This happens every time a user tries to access something, Logging on to the machine requires user rights to the network through a stored database of names and passwords, it then kicks in a series of commands linked to the machine called a script that gives the user rights to areas on the network from that machine. When they print, they need user rights, when they access the network, they needs Internet permission rights, when they go onto the VLE they need rights, ePm rights, Group rights, Directory rights, student and staff rights, read and write rights Etc.

All these are tied up in scripts stored on the network that load every time a student logs in. Setting these is the job of the network manager, and setting levels is their job too. A teacher has more rights than a students, an administrator in finance needs rights to the finance database etc.

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There are two kinds of authentication that goes on when a user switches on a machine, User and Hardware.

Hardware Authentication – This happens when a user tries to add something to the network, a scanner, a printer, their phone, a piece of software etc. There are two levels of Hardware rights, User and Administrator, there can be multiple administrators and each can have a different level of access.

It stands to reason that at least one network user must have the authority to use the network without any of the restrictions imposed on other users. This user is called the administrator. The administrator is responsible for setting up the network’s security system. To do that, the administrator must be exempt from all security restrictions. In a locked down system, only the administrator has Hardware rights to protect the network.

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Although you can share a printer or scanner on a network by attaching the device to a server computer, many printers have network interfaces built in. This lets you connect the printer directly to the network. Then network users can connect to the printer and use it without going through a server.

Even if you connect a printer directly to the network, it’s still a good idea to have the printer managed by a server computer running a network operating system such as Windows Server 2003. That way, the server can store print jobs sent to the printer by multiple users and print the jobs in the order in which they were received.

After you have installed the network printer, printing to the network printer is a snap. You can print to the network printer from any Windows program by using the File➪Printcommand to summon the Print dialog box. Near the top of this dialog box is a drop-down list titled Name, which lists all the printers that are installed on your computer. Choose the network printer from this list and then click OK to print your document. The benefits include:

Print Servers hold jobs until the printer is ready even when turned off.

Network printers can be shared by everyone

They can be restricted to a group or just a room

Installing drivers can be done from the network

Pcount can allocate funds and restrict users who have printed too much

Replacing the printer is as simple as replacing one installation and changing the DNS queue.

Using network programs the printer can be monitored. 6

Many network servers exist solely for the purpose of making disk space available to network users. As networks grow to support more users, and users require more disk space, network administrators are constantly finding ways to add more storage to their networks. One way to do that is to add additional file servers. However, a simpler and less expensive way is to use network attached storage, also known as NAS.

A NAS device is a self-contained file server that’s preconfigured and ready to run. All you have to do to set it up is take it out of the box, plug it in, and turn it on. NAS devices are easy to set up and configure, easy to maintain, and less expensive than traditional file servers.

A typical entry-level NAS device is the Dell 725N. This device is a self-contained file server built into a small rack-mount chassis. It supports up to four hard drives with a total capacity up to one terabyte.

After that the network can have added rack mounted hard drives, and as the network grows, more hard drives. The benefits include:

Upgradeable

Can have backup drives

Can use shared allocation and rights to files

Users can have their own space which can increase or decrease

Admin and Student drives can be separate for security reasons

Drive letters can be allocated for easier use. 7

A database server is a server computer that runs database software, such as Microsoft’s SQL Server 2000. Database servers are usually used along with customized business applications, such as accounting or marketing systems. Everything piece of stored information on the network is stored in some kind of database. For instance a domain is a method of placing user accounts and various network resources under the control of a single directory database.

All the information about a member of staff is stored on a database (age, name, address, qualifications, wages), this is linked to the Active directory database (groups, rights, files and folders, permission) and this is linked to Workgroups (students they teach, subjects they deliver, Intranet rights) and this is linked to the reports database (Reviews, reports, Assessments). Linking all these is the key to a good working network. From the moment we log in to the moment we log off, we would expect this database structure to be intact, easily accessible and available at all times. Programs like Microsoft Server, MySql, and Active directories help us to achieve that task.

Protecting that structure is also important, under the Data protection Act that information must be kept safe, under the Child Protection Act that information needs to be restricted, under good working practices that information needs to be backed up regularly on and off site which means backup servers, tape drives, UPS and management systems.

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When a user running a Web browser requests a page, the browser uses HTTP to send a request via TCP to the Web server. When the Web server receives the request, it uses HTTP to send the requested Web page back to the browser, again via TCP. A Web server is a server computer that runs software that enables the computer to host an Internet Web site. The two most popular Web server programs are Microsoft’s IIS (Internet Information Services) and Apache.

The job of this web server is to:

Monitor incoming traffic

Filter sites

Send and receive search requests and display results

Allocate the search result to the appropriate computer

Allocate rights to searches for restricted users

The job of a good server is to learn from the results, allowing the network manager to adapt the content addresses and filter these blocks appropriately such as tunnels, pipes, proxy bypasses etc. With the internet changing all the time, this is an ongoing routine, helped by the use of network logs.

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A proxy server (or Application Gateway) is a server that sits between a client computer and a real server. The proxy server intercepts packets that are intended for the real server and processes them. The proxy server can examine the packet and decide to pass it on to the real server, or it can reject the packet. Or the proxy server may be able to respond to the packet itself, without involving the real server at all.

For example, Web proxies often store copies of commonly used Web pages in a local cache. When a user requests a Web page from a remote Web server, the proxy server intercepts the request and checks to see whether it already has a copy of the page in its cache. If so, the Web proxy returns the page directly to the user. If not, the proxy passes the request on to the real server.

Application gateways are aware of the details of how various types of TCP/IP servers handle sequences of TCP/IP packets, so they can make more intelligent decisions about whether an incoming packet is legitimate or is part of an attack. As a result, application gateways are more secure than simple packet-filtering firewalls, which can deal with only one packet at a time.

A good proxy server will:

Learn from attacks and add them to a barred list

Download updates from an online security system like Janet

Filter the network as an added level of protection.

Act as a barrier, together with the firewall and SSL against DOS attacks.10

Places where wireless Internet access is available to the public are called hot spots. Some organizations, such as BT Wi-fi, have established a network of hot spots across the nation. Other organizations, such as a local coffee shop, might have only one hot spot. In some cases, Internet access is free. In other cases, the organization running the hot spot requires users to pay based on their usage or subscribe to a service. An average subscription costs £20 to £30 per month. There are many issues involved from Security to Access Rights, Capability to Compatibility when it comes to working through the network with Mobile Access.

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Security: To make IP addressing transparent for mobile users—A person visiting your office, for example, could attach to your network and receive an IP address without having to change the laptop’s configuration.

Transferring – Phones have the ability to upload either remotely or directly, direct access will involve Bluetooth, USB or Wi-Fi access, all of which needs configuring. Remotely this will require authentication which again can be an issue with storage, theft, times out access etc.

Connectivity – Signals break up, it is that simple, and transferring information usually require a constant stream of packets or rick losing packets. For some files one fraction of a second of loss can damage a file. In mobile wireless, the receiver can be located anywhere within the transmitter’s range. This allows the receiver to roam from one place to another while continuing to pick up its signal.

Reassociation - Connecting to a different access point requires Reassociation. Reassociation occurs when a mobile user moves out of one access point’s range and into the range of another. It might also happen if the initial access point is experiencing a high rate of errors.

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VoIP, (Voice Over IP (Internet Protocol) works much the same as a regular telephone. However, instead of connecting to the public telephone network, your phones connect directly to the Internet. The main benefit is reduced cost, especially if you make a lot of long distance phone calls.

When you use a normal phone to make a long distance call, your voice is transmitted (usually in digital form) over a network called the Public Switched Telephone Network, or PSTN. Along the way, you’re charged by-the-minute fees by your long distance service provider.

When you use VoIP, your voice is still converted into digital form. However, instead of being sent over private networks owned by telephone companies, it is sent over the Internet. Because the Internet uses the IP protocol, the digital data that represents your voice must be converted into packets that can be sent reliably over IP. Hence the name, Voice Over IP, or VoIP. The benefits to a business of VoIP include:

Free calls to other VoIP connections

Ability to send files on more secure systems

Running through a network would allows users to VoIP internally

An “Always On Connection” indicates locality using an IP address.

Reduces the need for email and mobiles

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