ITGS Network Architecture

ITGS Network architecture –The way computers are logically organized on a network, and the role each takes. Client/server network - One or more computers act as servers that provide services to the rest of the network (the clients) –Many advantages because files are located on a server can be accessed by owners from any client »If a computer needs to be repaired, files are not lost since they are saved on the server, not the computer »Because the server authenticates users, security is improved

ITGS Thin client network - client computers rely heavily on a server not only to store files and applications, but run software on a client’s behalf (sometimes including even the OS) –The thin client merely acts as a terminal for accepting input and displaying output The client only contains enough software to initialize the hardware and network connection, and connect to the server Because this is all they do, clients have very low specifications –No secondary storage –Slow processors –Small amount of RAM

ITGS Peer-to-peer networks - every client (peer) has equal status, and there is no central authority or server –Common in homes and small businesses where a server is too expensive/ not necessary Each computer shares the files from its own hard disk, and other machines are able to access them With more than a few users, the lack of a server to aid in security and storage becomes a problem

ITGS Firewalls –Hardware or software that determines which data is allowed to enter and leave a network Can be dedicated computers or built into network routers –Firewalls help secure a computer by preventing network access from unauthorized users –They also control which users and programs are allowed to connect to an external network such as the Internet Firewalls can be configured to allow or block traffic using several methods: –IP addresses - IP addresses of specific computers can be allowed or denied access »Denial of Service (DoS) - an attack by malicious computer users that bombards a site’s servers until the site doesn’t work »In one of these attacks, the IP addresses of the attacking machines can be blocked

ITGS Domain names - access to particular websites such as social networks can be blocked by specifying their name Protocols and ports - different protocols can be blocked or allowed as needed: Web browsing (HTTP) Mail (SMTP and POP3) File transfer (FTP) These protocols use a standard port, and the ports can be blocked as well For example, HTTP is port 80 Application program - individual programs can be granted or denied network access This is most important for programs that try automatically to update themselves or update themselves

ITGS Controversy over firewalls –While they can be used for protections, governments can also use them to deny services Proxy servers –Act as a middle step between two computers Usually between a computer on a LAN and a web server on the internet –All communication through the two computers passes through the proxy »The proxy caches, filters, and logs data (like users’ web activity) Caching - (saves time and bandwidth) –A process used to speed up activities like web browsing »Proxy servers keep a copy of commonly requested material, such as a web page, in a storage area called a cache. »When a user requests the webpage, the proxy server provides it from the local cache rather than retrieving it from the internet