real stuff.

Thursday, May 24, 2012

Week 11 - security

this topic was not supposed to be on Week 11, but I could not remember what week is this topic taught. so, let's just assume it is on week 11 as I have to put the topics in order. This week topic is on security!

networking security is becoming more and more important as people spend most of their time connecting with other people. we can have many attacks from any connection that you have in this world. therefore, there is a need to remember that this problems can be a serious matter if people choose to ignore it.

few examples of attacks a user may face:

1) Attacks against IP
- IP spoofing : a condition where one host stated that they have the IP address of another.
- IP session hijacking : the hacker can gain control to any type of actions that a user is doing. for example, while writing an email, a hacker can take command of the email thus manipulating it for their own benefits.

2) Data destruction
- this involves attacker just delete anything they want for their entertainment

there are a few protection that a user can provide to their computer to prevent this attacks :

1) Firewall
- with Firewall, we can control the information that goes in and out of our network.

2) VPN (Virtual Private Network)
- VPN's are a way to establish a "virtual" network on top of some already-existing network. This virtual network often is encrypted and passes traffic only to and from some known entities that have joined the network. VPNs are often used to connect someone working at home over the public Internet to an internal company network.

3) NFS (Network File System) security
- many sites use NFS to serve home directories to users. therefore, anywhere they login, they will easily directed to their home files. it involves exporting the file systems.

simple precautions that a user can take to assist them if they are attacked :

1) always backup files so that if any of the documents are deleted, you will not be too depressed if you lose your important work.

2) keep your antivirus up-to-date so that your computer can repair any kind of viruses that are sent by this hacker a.k.a attacker

3) be familiar with all security services so in case of any attacks, you know what to do.

VIRUS

A computer virus can cause a lot of damage to files and softwares. here are a few viruses that we mostly heard:

1) WORM
- small piece of software that uses computer networks and security holes to replicate itself. A copy of the worm scans the network for another machine that has a specific security hole. It copies itself to the new machine using the security hole, and then starts replicating from there, as well.

2) Trojan horse
- is simply a computer program. The program claims to do one thing (it may claim to be a game) but instead does damage when you run it (it may erase your hard disk). Trojan horses have no way to replicate automatically.

3) Melissa virus (1999)
it is so powerful that it forced Microsoft and a number of other very large companies to completely turn off their e-mail systems until the virus could be contained.

Tuesday, May 22, 2012

week 10 - HTML

today's topic is HTML which stands for Hyper Text Markup Language

HTML is not a programming language. just like the name suggests, it is used to markup language. a markup language is a set of markup tags. the tags are designed to describe page content.

example :

This is a paragraph.

The correct structure for an HTML document starts with <HTML><HEAD>(enter here what document is about)<BODY> and ends with </BODY></HTML>. All the information you'd like to include in your Web page fits in between the <BODY> and </BODY> tags.

An HTML element starts with a start tag / opening tag
An HTML element ends with an end tag / closing tag
The element content is everything between the start and the end tag
Some HTML elements have empty content
Empty elements are closed in the start tag
Most HTML elements can have attributes

examples :

<!DOCTYPE html>
<html>

<body>
This is my first paragraph.
</body>

</html>

The body element

<body>
This is my first paragraph.
</body>

The <body> element defines the body of the HTML document. The element has a start tag <body> and an end tag </body>. The element content is another HTML element (a p element).

The HTML element

<html>

<body>
This is my first paragraph.
</body>

</html>

The <html> element defines the whole HTML document. The element has a start tag <html> and an end tag </html>. The element content is another HTML element (the body element).

Empty elements

HTML elements with no content are called empty elements.

is an empty element without a closing tag (the tag defines a line break).

Tip: In XHTML, all elements must be closed. Adding a slash inside the start tag, like , is the proper way of closing empty elements in XHTML (and XML).

Elements can have attributes

attributes is the argument inside a HTML tags.

<A HREF="http://www.somewhere.ca/file.html"> marked text </a>.

the element A is the markup for the beginning of the elements. one of the attributes is HREF, a place where the hypertext link in the webpages. to specify the this in the tag, user should write like above. where the attribute HREF is assigned the indicated value. Note that the A element is not empty, and that it is closed by the tag </a>. Note also that end tags never take attributes -- the attributes to an element are always placed in the start tag.

Sunday, May 20, 2012

Week 9 - Web Conference

Web conference is used to conduct live meetings, trainings, or presentation via the Internet. we can see the same screen at all times in our web browsers. in web conferences, there are features such as VoIP, full-motion video and texting. businessman can conduct their business over web conferences, users can make presentations or demonstrations. however, to make an effective web conferences, users must have a fast Internet connection that is reliable.

ADVANTAGES AND DISADVANTAGES OF WEB CONFERENCING

Advantages :

available to anyone with a computer and an Internet access
participants may attend meeting from their normal work stations without travel
lowest cost delivery

Disadvantages

Low resolution will result in good quality
participants may not have a high quality Internet access
creates no sense of impact or community among participants

Friday, May 18, 2012

week 8 - FTP

the other day I wrote about email. today's topic is also related to email. however, since my last post was too LONG, i decided to write FTP in other entries. here it goes.

TELNET

it is a utility program designed which allows you to become a user of a remote computer. However, it does not allow user to transfer files among computers. you can create, delete files and many more even if you are not in front of a computer. user can log on to a remote computer as a regular user and obtain any information that they want. Example of TELNET that we can see daily is the OPAC.

File Transfer Protocol (FTP)

It is a protocol used to transfer files from one host to another using TCP-based network such as the Internet. we can also upload and download files quickly on the Internet using FTP. it works the same way as HTTP, transferring web pages from a server to a browser. it is also similar to SMTP as it transfers email across in the Internet. in order to manage connection between server, clients need to run an FTP server. FTP will then provide a window that can be copied into client's storage media. FTP may run in active or passive mode, which determines how the data connection is established. passive mode is used if the clients is behind a firewall. in active, a TCP connection is created. the client will send the IP address and port number to the server and then wait until the connection is connected.

anonymous FTP

A host that provides an FTP service may provide anonymous FTP access. Many FTP hosts whose purpose is to provide software updates will provide anonymous logins.

Benefits of FTP
-One of the biggest advantages of file transfer protocol is that it is one of the fastest ways to get large files from one computer to another.
- Most FTP servers require you to log in with a username and password.
- FTP allows you to transfer files back and forth. This means that if you are an owner of a company, you can send information to your employees and they can send information back all on the same server.

HOW TO UPLOAD OR DOWNLOAD USING FTP

1) Install an FTP software program on your hard disk. Open the program.

2) Enter the host address in the text box provided.

3)Enter whatever passwords or IDs have been provided if this is an anonymous login. For example, you may have been asked to login as "guest" and use your e-mail address as the password.

4) Enter whatever password and ID you have arranged with the remote administrator if it is not an anonymous login.

5)Click Connect to establish a connection. When the connection is established, the window on the right side of the screen represents the remote site.

6) Move through the remote folders until you locate the file that you want to download, and select the file.

7)Move through your hard disk (the window on the left side of the screen) until you have opened the folder that is to receive your new file.

8)Select the remote file on the right window, and drag it to the window on the left. Most FTP programs allow you to download files this way. If your software does not allow this method, consult the help file to see how to start the download. When the download is complete, you will find your new file in the location that you specified.

Wednesday, May 16, 2012

week 8 - email!

Week 8 it is. today's topic : EMAIL

Electronic mail or E-mail, is an ordinary mail but is sent in seconds via Internet. we can accept mail, deliver and even store the messages nowadays. it consists of three components, which are the header, the body and the message envelope.

what are the advantages of using email to send message?

Email is a convenient style of sending message as user do not have to go anywhere to send their email. apart from that it is fast, as it only takes seconds or minutes to reach the recipients. it is inexpensive and user can also send email via wireless connection. it is reliable as the sender will be able to know directly if the email they send reach the recipients or not. user can also send images, videos and not just texts to the recipients which show the advanceness of technology nowadays.

what are the disadvantages of email?

however, email also has a bad side of it as well. once we sent an email, there is no way we can retrieve it back. this is very dangerous especially if we sent a confidential information to a wrong person. apart from that, if we mispell a letter in an email address, we might end up sending the email to another person. as I've said before, this is dangerous especially if you are sending a confidential information. we also receive a lot of spam if we click to other websites that is not secured. if we click the spam, our computer might be attacked by virus that will crash the whole system.

MAIL SERVER

mail server consists of a storage area where email is stored for local users. it has a database and a software or program that can send or receive email from or to other email servers.

EMAIL CLIENT

it is a software or program that can transfer email from a local host to a local email server. it is a program used to manage and access a user's email. Popular email client included Microsoft Outlook, Mozilla's Thunderbird, and many more.

EMAIL TERMS

CC - Carbon copy

- send a message to more than one person, all the recipients will be able to see the list of email addresses

BCC - Blinded carbon copy

- the recipients will not be able to see the list of email addresses

- it is used when we want to send email to people who don't know each other

Subject

- the keyword for the content of message, like a title

HOW DOES EMAIL WORK

SIMPLE MAIL TRANSFER PROTOCOL

SMTP is a Internet term across IP network. While electronic mail servers and other mail transfer agents use SMTP to send and receive mail messages, user-level client mail applications typically only use SMTP for sending messages to a mail server for relaying. client can also retrieve their email using IMAP (Internet Message Access Protocol) or POP (Post Office Protocol)

POP ( Post Office Protocol)

POP is used by email clients to retrieve email from a remote server over TCP/IP connection. most webmail service also provide POP and IMAP service. Although most POP clients have an option to leave mail on server after download, e-mail clients using POP generally connect, retrieve all messages, store them on the user's PC as new messages, delete them from the server, and then disconnect.

IMAP (Internet Message Access Protocol)

it is a method of accessing electronic mail or bulletin board messages that are kept on a mail server. E-mail clients using IMAP generally leave messages on the server until the user explicitly deletes them. Most e-mail clients support IMAP in addition to POP to retrieve messages; however, fewer email services support IMAP.[2] IMAP offers access to the mail storage. Clients may store local copies of the messages, but these are considered to be a temporary cache.

Bounced back email

bounced back email occur when the message did not reach the recipients and is sent back to the sender with an error message that shows that the email is not successfully sent. the message is also bounced back when the server of recipients is busy and could not handle the request at that time. Occasionally, a network failure at the sender or recipient end will cause an e-mail to bounce back to the sender. Typically, a bounced e-mail returns to the sender with an explanation of why the message bounced.

Monday, May 14, 2012

Week 7-Web Browser

welcome to week 7, yep. i have been procrastinating for a while now. so I'm gonna catch up soon!

this week topic : WEB BROWSER (WEB SEARCHING & WEB RESOURCE EVALUATION)

what is web browser?
it is a software application for retrieving, presenting and traversing information resources on the World Wide Web. in short, it is an application where human search any enquiries that they have. we can search for image, text, videos and any other information that will assist user in their work.

of course, we work with a lot of Web browser. which one do you frequently use? to me, it has to be Google Chrome. most of the Web browser all over the world are Google Chrome, Firefox, Internet Explorer, Opera, and Safari.

what are the terms used in Web Browser?

1)HTTP - hyper text Transfer Protocol
2) URL - Uniform Resource Locator
- URL is the address input by the user into the browser. The URL will bring the user into the web pages they desire
3) HTML - HyperText Markup Language
- HTML is passed to the browser's layout engine to be transformed to an interactive document.

what are search engines? it is a program where user key in a specific keyword to find the information that they want. just like web browser, the information that come out will be in the form of images, text or videos depends on how you want it. i prefer using Google as my search engine as they are faster. major search engines that are used in the whole world are Google, Yahoo, Bing, and Ask.com. the video below shows you how do search engine work so that we can get information.

WEB DIRECTORIES

web directories is not a search engine and it is built by humans. unlike search engine, it is a list of websites that are listed based on their category or subcategory.

META SEARCH

it is similar to search engine however it brings user to several search engine at one time. Metasearch enables user to find several information once without having to open several search engine to find what they want.

here are a few tricks that will maximise your use in the searching information:

1) if you want to find a meaning of a word in the search engine, instead of just typing aggregate, you may type define : aggregate. you will be directed into the specific meaning of aggregate instead of getting useless information about it. \

2) If you are looking for a definition of a term, put a quoting mark at the term so that you will be directed into the definition of a term instead of just getting a review of someone on their blog about the term . Example : "The Murphy's Law". this can also be applied if you are searching for a picture for Rachel Adams for instance. put a quote on her name. "Rachel Adams" and you will found only her pictures and not someone else.

this is just some tricks that I know and it is really helpful. enjoy! XD

Sunday, May 13, 2012

Week 6 - Internet

we're back to Week 6! yes, i'm a bit behind now, but I'm trying to catch up. i hope there's till time. we will start with the introducing you to the definition of Internet.

what is Internet?

An international computer network providing e-mail and information from computers in various places such as schools, offices, government services, and etc.

what is Internet infrastructure?

All the hardware and services required to make this web page appear in your browser, or an RSS feed download into your reader, or VOIP calls / emails get to your desktop. All the underlying technologies that are unseen, but ‘make the Internet go’.

TCP/IP protocol (Transmission Control Protocol/Internet Protocol

is the basic communication language or protocol of the Internet. it can also be used in private network as a communications protocol. many Internet user are not really familiar with the term TCP/IP. however, they did not know that they often use the protocols that use TCP/IP to get to the Internet. the examples are FTP (File Transfer Protocol), TELNET which let you logon to remote computers and HTTP (Hyper Text Transfer Protocol)

Internet protocol

every machines in the Internet have a very unique number that can be identify easily, which is called IP address. IP refers to Internet protocol, the system to communicate over the Internet. The four numbers in IP adress is called octets. the octets are there for a reason. it is used to differentiate classes in the IP address. IP address is used for two purposes which are network interface identification and location addressing.

there are a few terms that one must know about Internet. they are :

1) DNS (Domain Name System)

a hierarchical, distributed database that contains mappings of DNS domain names to various types of data, such as Internet Protocol (IP) addresses. DNS allows you to use friendly names, such as www.microsoft.com, to easily locate computers and other resources on a TCP/IP-based network. DNS is an Internet Engineering Task Force (IETF) standard.

2) IP address

every machine in a network has a unique identifier. it is also called an Internet address.

Thursday, May 3, 2012

week 5

it has been really a while since the last time I updated my blog. sorry sir! :( so, here comes week 5!

WIRELESS

where do you actually found wireless? it's all around us! ask any kids, they know a lot about wireless. so today, we gonna dig in into this wireless topic. it is commonly used in many IT unit and equipment, such as GPS navigator, wireless keyboards and many more.

wireless enable people to connect networking using wireless connection across long distances. there are also infrared and radio frequency, but they are limited to area that is short-ranged. wireless are often defined as electronic waves, radio waves, and infrared.

what are the devices that we know use wireless communication or networking?

1) Hand-held computers

2) Handphones (to connect to email and social networking)

3) GPS

4) Laptops

5) Desktop computers

APPLICATION OF WIRELESS TECHNOLOGY
1) Voice and messaging
Eg: Cellphones, PDA
2 ) Handheld devices

3) Data Networking

MOBILE PHONES 1G, 2G, 3G, 4G

Tuesday, March 27, 2012

Week 4

Chapter: Network hardware

assalamualaikum~

Today, my entry will be on network hardware. But on top of that, let's just browse through the network architecture. There are two major types of network architecture:
a) Peer-to-peer

workstations connected to each other but do not have servers.
files can be shared between workstations and also the printers.

b) client/server network

consists of two kinds of computers
clients are the workstations, servers are powerful computers and held in central locations.
need client software and server software

let's skip the architecture part and went straight to the hardware. what are the equipments available in network hardware?

1. Client - servers configuration

server - controls the communication of information between the nodes on a network.
client/ workstations - all computers connected to the file server on a network

2. Network Interface Card

provides the physical connection between the network and the workstation
necessary to determine the speed and performance of network

3. Repeaters

connectors that take signals that is being transferred on a network and re-transmits the information.
allow signal to travel farther along a network
do not operate efficiently when they have to transfer large amount of information.

4. Hub/Switch

device that provides a central connection point for cables from workstations, servers and peripherals.
multislot concentrators
passive hubs - do not process information, connect wires to the network
active hubs - amplify signals to eliminate errors on the network.

5. Bridges

allows computer on individual networks or separate parts of a network to exchange information.
can only transfer information from one network to another.
split an overloaded network into smaller parts.

6. Routers

link different networks together.
analyse the information passing through to prevent looping problems.
determine the best route for information

7. Gateways

link two different network types together.
a hardware device that connect to the network physically and transfer information between them.

8. Modems

allow computers on a network to exchange information.
translates information into a form that can be transmitted over telephone lines
inexpensive way of communication

CABLING

UTP Cable connectors

unshielded twisted pair cabling is an RJ-45 connector.
a plastic connector that looks like a large telephone-style connector.

Coaxial cable connector

familiar from TV cable and VCR.

Fibre optic connector

common used in fibre optic connector is the ST connector.

Thursday, March 15, 2012

Week 3

few of my friends actually told me that my blog looks really simple. to me, the content of the blog should be precise and packed but in a brief way explained. I have another blog before, and believe me people hate to read long posts. so I choose to make my content simple yet precise.

this week's chapter: Computer Networking and Network Topology

we actually learn a bit about computer networking in the previous class, so i was just going to recall what we have learn.

Computer Network: connecting computer to computer / devices
It also enable communication between:
a) Computer devices/equipment
b) Transmission media to send/control data/signals
c) Communication devices to transmit/send data from sources to destinations
d) Softwares

Many types of network exist, but the most common types are:
a) Local Area Network (LAN)
b) Wide Area Network (WAN)
c) Metropolitan Area Network (MAN)
d) Personal Area Network (PAN)

the next chapter that we learn is the topology. topology is one way that the networks are being categorized. It specifies the geometric arrangement of the network. It has both logical and physical level in its structure.

Physical level:
- the way that devices on a network are arranged

Logical level
- the way the signals act on the network media/ the way that the data passes through

we will go through one by one of this topology. first is the BUS NETWORK STRUCTURE.

BUS
- a continuous length of cable that connects two or more devices together.
- it can only transfer information one at a time.
- each end of the cable on the bus network must have a terminator ( a device that absorbs signal transmitted on a network cable)

STAR NETWORK STRUCTURE
-consists of individual computer connected to a centre point of the network.
-each computer is connected to a central network connector, called a hub.
-It is commonly used as if there are error in one of the computers or cable, the rest of the network will be unaffected.

RING NETWORK STRUCTURE
-consists of individual computers connected to a single length of cable arranged in a ring.
-information travels in one direction only
-must be attached to a single ring cable

HYBRID NETWORK STRUCTURE
-a mixture of many different kinds of network structure. It can incorporate structures such as ring, star, and bus network in one large network.

that's all for now. It's a long entry. Well, we do learn a lot right? see you in my next entry! XD