Po Leung Kuk Wu Chung College Hkcee Computer And

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HKCEE 2007 COMPUTER AND INFORMATION TECHNOLOGY Po Leung Kuk Wu Chung College HKCEE Computer and Information Technology Paper III: Project Report（ （2007） ） Module C: Cyber Café in School Name: Class: Class No.: Registration No.: Ma Yuk Chun 5D 9 20021610 PAGE.PAGE.- 1 PAPER III: COURSEWORK REPORT MODULE C – MA YUK CHUN HKCEE 2007 COMPUTER AND INFORMATION TECHNOLOGY Contents Objective and Analysis Discussion and Working Schedule Network Design and illustration Network Diagram Explanation of the diagram Connection Method Switching hub and Router DHCP Server Cable used Samba Server-user identification Network Feature Communication Speed Costing Network Security Clam Anti-Virus Proxy Server Router Add-on Service Network Printer File Sharing Webmin and Usermin Evaluation Testing result Conclusion PAGE.PAGE.- 2 PAPER III: COURSEWORK REPORT MODULE C – MA YUK CHUN HKCEE 2007 COMPUTER AND INFORMATION TECHNOLOGY Objective In this project, our school is going to establish a cyber café for student use. In this area, we have decided to provide several computers and used the star topology for network connection. Though this network system, each student will be given a unique account for login. Those students having login can enjoy different kinds of services. Such as high speed internet access, file sharing, printing service etc. Also, student will be given an e-mail account. Ensuring the entire user can take the advantage of our grateful environment and make them feel completely relaxed. Analysis In the network server, we have installed “Linux Terminal Server Project” [including FTP, Samba Server]. LTSP is open-source operating systems which can be downloaded free of charge from the Internet and modify its actual source code. It also belongs to ‘Network Operating System’ which runs on network servers and provides centralized storage facilities and communications capabilities for networks. LTSP is an add-on package for Linux that allows us to connect the low-powered thin client terminals to a Linux Server. Since LTSP is open-source software and free for downloading. Therefore, we can get it from the website: (http://www.ltsp.org ) PAGE.PAGE.- 3 PAPER III: COURSEWORK REPORT MODULE C – MA YUK CHUN HKCEE 2007 COMPUTER AND INFORMATION TECHNOLOGY Discussion and Working Schedule Discussion with Mr. Yeung Discussion Subject Date and Time Network Design 22/8/06 10:00 - 11:30 About Linux 24/8/06 2:00 - 3:00 Network Security 8/9/06 11:15 – 12:10 Time used 1.5 hours 1 hours 55 Mins Discussion with Mr.Yeung Mr.Yeung Mr.Yeung Working Schedule Date 24 August 25 August Time Used Around 2 hours Around 50 Mins 15 September 16~19 September Around 45 Mins Around 2.5 hours 21~22 September 7 November Around 1 hours Around 35 Mins 9 November Around 20 Mins 17 November Around 30 Mins 22~24 November Around 2 hours 8 December Around 5 hours Work Installing Linux Installing Samba and Network setting Question Analysis Search the information on the internet Add-on Services Create the Project [Menu & Objective] Fixed user identification problem Set up firewall and adjustment[Clam-Antivirus] File sharing and Printing sharing [Final Adjustment] Project Finished PAGE.PAGE.- 4 PAPER III: COURSEWORK REPORT MODULE C – MA YUK CHUN HKCEE 2007 COMPUTER AND INFORMATION TECHNOLOGY PAGE.PAGE.- 5 PAPER III: COURSEWORK REPORT MODULE C – MA YUK CHUN HKCEE 2007 COMPUTER AND INFORMATION TECHNOLOGY Introduction of the diagram In this network system, one of the computers has installed Linux Terminal Server Project (LTSP) which contain DHCP server. There are two Network Interface Cards (NIC) in this Server. One of them is connected to the school network and gets the IP address by 172.16.x.x. Another one is connected to the cyber café network. After setting up the network connection, Linux server will act as DHCP server and assign the dynamic IP (192.168.0.xxx) to each workstation. Therefore, all of them can access to the internet. Linux server also consists of Samba server. If the user want to enjoy the use of add-on services, they may need to get a special account which assigned by Samba server. Specification The follow assumption for the cyber café network: The cyber café has 10 computers Internet access is available All of individual server (Samba server, DHCP server …) PAGE.PAGE.- 6 PAPER III: COURSEWORK REPORT MODULE C – MA YUK CHUN HKCEE 2007 COMPUTER AND INFORMATION TECHNOLOGY Connection Method Our network is wired. Each workstation has a cable connected to the Switching hub. Star Topology: In my network system, I have determined to use Star Topology. In this topology, all the workstations are connected to the switch hub. I chose this method because it is easy to install and wire. Because of wire, it has no disruptions to the network then connecting or removing devices. The main reason is that each workstation is independently connected to the server. A major disadvantage of this type of network topology is that if the central hub fails, all computers connected to that hub would be disconnected. Bus topology: I have also considered using linear bus, but the entire defect made me change the idea. I found that bus network is a network architecture in which a set of clients are connected via a shared communications line. It is the simplest way to connect multiple clients, but often have problems when two clients want to transmit at the same time on the same bus, it is called collision. Linear bus is easy to implement and extend but it imposes severe limitations on distance and scalability. The central cable broken or one of the node fails can disable entire network. The serious problem is the lower security; all computers on the bus can see all data transmissions. One virus in the network may also affect all of them. PAGE.PAGE.- 7 PAPER III: COURSEWORK REPORT MODULE C – MA YUK CHUN HKCEE 2007 COMPUTER AND INFORMATION TECHNOLOGY Switching Hub Switches also have been used. It has more advanced functions than traditional hub. Instance, a network built with switches is generally considered faster than one built with hub. When a hub receives a packet of data at one of its ports from a PC on the network, it resends the packet to all of its ports and to all of the other PCs on the network. If two or more PCs on the network try to send packets at the same time a collision is said to occur. Also, this may increase the rate of network congestion. Switching hub uses the similar rule of crossover. When the switches receives a packet, it reads the destination address from the header information that it has learnt it before, establishes a temporary connection between the source and destination ports, sends the packet on its way, and then terminates the connection. Just like two computers is connected directly together by using crossover cable. Ones receive a file and transmit it to the destination. Also switches prices are dropping so that there is very little difference from hub prices. So, I chose it. Router In my café network, Linux Server acts as a router. It is used to connect to the Internet for translating information between the LAN and Internet. A router just like a junction between this two networks to transfer data in packets. Routers also handle certain functions, such as routing and managing the traffic on the networks. In addition, routers also provide DMZ and firewall services, so it can provide content filtering. Router occurs at Layer 3 (The network layer of occurs at Layer 3 (the network layer of OSI seven-layer Model.) PAGE.PAGE.- 8 PAPER III: COURSEWORK REPORT MODULE C – MA YUK CHUN HKCEE 2007 COMPUTER AND INFORMATION TECHNOLOGY Dynamic Host Configuration Protocol Server DHCP is the short form of Dynamic Host Configuration Protocol. DHCP is a protocol used by networked computers (clients) to obtain unique IP addresses, and other parameters such as default router, subnet mask, and IP addresses for DNS servers from a DHCP server. I use this protocol since it is used when computers are added to a network because these settings are necessary for the host to participate in the network. The length of time the IP address is available to the device is according to the rule of lease and is determined by the server. The DHCP server ensures that all IP addresses are unique, that is, no IP address is assigned to a second client when the first client's assignment is valid (its lease has not expired). In my network, there are three clients connect to the server. Those of them was added to the subnet “192.168.0.0” The latest non-standard of the protocol, describing DHCPv6 (DHCP in an IPv6 environment), appeared in July 2003 as RFC 3315 PAGE.PAGE.- 9 PAPER III: COURSEWORK REPORT MODULE C – MA YUK CHUN HKCEE 2007 COMPUTER AND INFORMATION TECHNOLOGY Information Security Based on the information security, I set up the range of dynamic IP address that those workstations can get (192.168.0.101~192.168.0.110) we can set these ranges in Webmin page (https://192.168.0.254:10000). Second picture shows the workstation in café network and get the IP (192.168.0.110). So this user can have a right of internet access. There are only allow at most 10 computers connected to my café network. These 10 clients can also access to internet as they get the IP address from the DHCP server. Nevertheless, these 10 clients could not get the add-on services without login the Linux Server. PAGE.PAGE.- 10 PAPER III: COURSEWORK REPORT MODULE C – MA YUK CHUN HKCEE 2007 COMPUTER AND INFORMATION TECHNOLOGY Default Gateway and Subnet Mask Default Gateway: In our school network, the address of default gateway is 192.168.0.254. A default gateway is a node (a router) on a computer network that serves as an access point to another network. In my café network, the gateway is the Linux server that connects the user to the Internet. The gateway is the computer that routes the traffic from a workstation to the outside network that is serving the Web pages. In other words, it is an entry point and an exit point in a network. Subnet Mask: In our school network, the address of subnet mask is 255.255.255.0. Subnet is a range of logical addresses within the address space that is assigned to an organization. The address to all nodes in a subnet starts with the same binary sequence, which is its network id and subnet id. In IPv4, the subnet may be identified by its base address and subnet mask. PAGE.PAGE.- 11 PAPER III: COURSEWORK REPORT MODULE C – MA YUK CHUN HKCEE 2007 COMPUTER AND INFORMATION TECHNOLOGY Cable Used in Cyber Café Network In this Cyber Café Network, I have settled on the Cat 5e cable for connecting all the computer and network device. A new specification for CAT5 cable, CAT5 enhanced (CAT5e), supports short-run Gigabit Ethernet (1000 Mbps) networking by utilizing all four wire pairs and is backward-compatible with ordinary CAT5. Cat 5e adds the specification for far end and crosstalk. Also, the cost of cat5e is not expensive and our café network not very extensive. Then, I chose it. Samba Server - User identification Samba is an open source software and print serving application that runs on many UNIX variants like Linux, IRIX and Solaris. We can use Samba to set up a print server, a basic file server or even a Windows domain controller. As we use the SAMBA utilities, integrating Linux into a Windows network is reasonable and easy. Samba server just looks and acts as any other server on a Windows intranet. The entire client will have the ability to drag and drop files, view server contents and directories using Windows File Manager, and even edit files on a Linux server from any Windows desktop. Linux Setting Firstly, I have installed Samba and created a samba user. The username I created will be stored into directories. Thus, that user is allowed access to the Samba server. Then, I transformed this UNIX user into Windows user via Webmin. After that, I made the changes to the server setting, including Windows workgroup name (Cyber-Cafe) and the Server description. In addition to use webmin, we can also use terminal mode to create the users for samba and windows use. PAGE.PAGE.- 12 PAPER III: COURSEWORK REPORT MODULE C – MA YUK CHUN HKCEE 2007 COMPUTER AND INFORMATION TECHNOLOGY Windows Setting Secondly, I did the step of access samba server from windows. Changing the workgroup into “Cyber-Cafe” then reboots the computer, the windows may request for a user name (using a samba created username) and passwords. In this time, we can found that the workgroup have been changed. It means the windows PC have joined to Server. At this moment, user can access to the Linux server and the services are provided. For instance, the printer services, access to the share file…etc. PAGE.PAGE.- 13 PAPER III: COURSEWORK REPORT MODULE C – MA YUK CHUN HKCEE 2007 COMPUTER AND INFORMATION TECHNOLOGY Network Communication Speed I have tested one of the computers in my café network. And the result is very great. I have tried to download a file from the internet; the file size is around 3.5 GB, and the download speed is over 55 Mb/s. Since our school network is provided 100Mbps bandwidth. In my network system, the network communication speed is very fast and steady. As I chose to use switching hub which is a device can select a path for sending data to its destination directly. This will reduce the network congestion. Also, Cat 5e cables are using for connecting all of client to the switches. Cat 5e cables are suitable for Gigabit Ethernet and also lessen the electromagnetic interference. Also, our school is using the 1Gbps bandwidth precisely. Eventually, I have chosen to use star topology which can reduce the influenced by each of the workstation fail. PAGE.PAGE.- 14 PAPER III: COURSEWORK REPORT MODULE C – MA YUK CHUN HKCEE 2007 COMPUTER AND INFORMATION TECHNOLOGY Power of Linux Server Costing The Linux Server is low-powered. Based on the above details, the CPU is 728.431 MHz only, and the RAM approximately 377 MB. Also, the total space of hard drive is around 25 GB. I have used LTSP which is open-source network operating systems. It can be downloaded free of charge from the Internet. This can save cost on buying operating system. LTSP is an add-on package for Linux that allows us to connect the low-powered thin client terminals. So it can save the money on buying new computer. Switching hub is old and provided by school. All the cables are secondhand and free to use. All the client computers are out-dated and low powered. PAGE.PAGE.- 15 PAPER III: COURSEWORK REPORT MODULE C – MA YUK CHUN HKCEE 2007 COMPUTER AND INFORMATION TECHNOLOGY Network Security Firewalls Firewalls are device that separate untrusted Internet locations from trusted internal networks. In order to keep the internal network secure from internet, we need to install firewalls. In my café network, Linux server act as Firewalls, Router and Proxy Server. In order to limit network access to authorized users. Clam Antivirus: One of the firewalls is called Clam Antivirus, is a widely used free antivirus software tool kit for Unix-like operating systems. It is mainly used with a mail exchange server as a server-side email virus scanner. ClamAV is open source software distributed under the terms of the GNU General Public License. Both ClamAV and its updates are made available free of charge. Proxy server: A proxy server is a computer that offers a computer network service to allow clients to make indirect network connections to other network services, just like a filter. A client connects to the proxy server and then requests a connection or other resource shared by all different servers. The proxy provides the resource either by connecting to the specified server or by serving it from a cache. In some cases, the proxy may change the client's request or the server's response. Router: Routers typically provide DHCP, NAT, DMZ and firewall services. Therefore, it has the function of filtering. Then, it is classified to firewalls. PAGE.PAGE.- 16 PAPER III: COURSEWORK REPORT MODULE C – MA YUK CHUN HKCEE 2007 COMPUTER AND INFORMATION TECHNOLOGY Add-On Services Network Printer Network printer is the one of the add-on services provided to client. Each client who has login the server is permit to use these kinds of services. Linux server act as print server and respond to manage print queue. In my network system, I have set up the shared printer called “hplj4”. All the clients have login is allowed using it via café network. The whole print job will not send out through the school network as the printer is located at café network (LAN). In honest, the Linux server just allows the intranet user. Through the samba to set the network printer is simple. Ensuring the printer is connected to the server and then alter the file called “smb.conf” stored in ‘ /etc/samba/ ’. PAGE.PAGE.- 17 PAPER III: COURSEWORK REPORT MODULE C – MA YUK CHUN HKCEE 2007 COMPUTER AND INFORMATION TECHNOLOGY File sharing File sharing is the practice of making files available for other users to download over the Internet and smaller networks. File sharing follows the peer-to-peer (P2P) model, where the files are stored on and served by the Server. Opened and edited some config file in samba server. At first, edit the file ‘ /etc/samba/smb.conf ’, in order to set the permission for the user. Now, the public file is opened and shared to whole users via café network. This file is available for users to alter the contents. Public file from wcc-ltsp-srv2 is readable and writable. But the file called Antony and Marco shared from wcc-ltsp-srv2 allow reading only. Some file contains important data may not willing to share to each user. Only the administrator has the permission to open and modify it. So I have made the changes to some particular config files. PAGE.PAGE.- 18 PAPER III: COURSEWORK REPORT MODULE C – MA YUK CHUN HKCEE 2007 COMPUTER AND INFORMATION TECHNOLOGY Introduction to Webmin Webmin is a system configuration tool for Unix-like systems. It has a web-based interface desktop environment independent, for configuring some of the internals of the operating system. Webmin is largely based on Perl, and is running as its own process, and web server. It usually uses TCP port 10000 for communicating. It is built around modules, which have an interface to the config files, and an interface to the webmin server. This makes it easy to add new functionality, without too much work. And due to Webmin's modular design, it would be possible, for anyone who is interested, to write plug-in for desktop configuration. Webmin also allows for controlling many machines through a single interface, or seamless login on other webmin hosts in the same LAN. Main page: http://www.webmin.com/ After installed the webmin, I can access the webmin through the web browsers. The website is: https://192.168.0.254:10000/ PAGE.PAGE.- 19 PAPER III: COURSEWORK REPORT MODULE C – MA YUK CHUN HKCEE 2007 COMPUTER AND INFORMATION TECHNOLOGY Introduction to Usermin Usermin is a web-based user interface for Unix-like systems. It is a simplified version of Webmin, can be used by any user on a Unix system, and is distributed under the BSD license. It consists of CGI programs in Perl that directly updates configuration files, and a simple web server. Any user on a Unix system to easily perform tasks like reading mail, setting up SSH or configuring mail forwarding. Obtaining Usermin Usermin is free under a BSD style license, just like its more powerful sibling. It can be downloaded for free from the Usermin site or one of its mirrors. For reference the primary Usermin site is www.usermin.com Like Webmin, Usermin is available in a tar ball, as well as an RPM for Red Hat, MSC Linux and Caldera. Unlike Webmin, there is currently no Solaris package of Usermin. PAGE.PAGE.- 20 PAPER III: COURSEWORK REPORT MODULE C – MA YUK CHUN HKCEE 2007 COMPUTER AND INFORMATION TECHNOLOGY In my Linux server, the Usermin Page is https://192.168.0.254:20000/ Preventing Spam Mail by Usermin These days, E-mail becomes very famous. Many people using e-mail instead of traditional mail. On the internet, there is million of spam mail on the internet every day. Some of these spam mail is carried virus that may affect our computer. Spam Assassin Mail Filter can help us to avoid these spam mail. It will scan all the mails we received, before we open it. After filtering, Mail will be classified. PAGE.PAGE.- 21 PAPER III: COURSEWORK REPORT MODULE C – MA YUK CHUN HKCEE 2007 COMPUTER AND INFORMATION TECHNOLOGY Testing In this cyber café, I have promised to provide high speed internet access, so I have tested two ways. From café network to outer network (WAN) and the local area network (LAN). From LAN (Café Network) to WAN (www.yahoo.com.hk) From LAN (Café Network) to WAN (www.yahoo.com.hk) PAGE.PAGE.- 22 PAPER III: COURSEWORK REPORT MODULE C – MA YUK CHUN HKCEE 2007 COMPUTER AND INFORMATION TECHNOLOGY Conclusion In order to receive more information in a limited place, I have established café network. In this cyber café, student can enjoy different kinds of service. Such as high speed Internet access, printing, file sharing, etc. Cyber café built in school purpose to give a place that students can slack off. Being a cafe with 10 computers and high speed Internet access, we have all the in-house resources. Study is not only in classroom, also can be just bump the keys. All in all, Cyber café is a perfect place to use the computer while having a café. In this project, I have encountered many problems. For instance, I set up the computer which will be installing Linux Fedora 4. But the out-dated computer can’t boot-up. After checking, I found that the problem is caused by the RAM. Although it is a hard job for me, it is worthwhile. References Reference website: http://fcit.usf.edu/network/ Searching engine: http://www.google.com.hk Reference book: LINUX 與 WINDOWS 共舞 – 異質平台整合方案 異質平台整合方案 ~The End of My Project~ PAGE.PAGE.- 23 PAPER III: COURSEWORK REPORT MODULE C – MA YUK CHUN