What is SMTP Server?

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What is SMTP Server?

STMP (Simple Male Transfer Protocol) is used for transfer emails. If you are using Microsoft Outlook or any email client for sending emails then you will use your ISP's SMTP server for sending emails, like you will type mail.yourISPdomain.com as your outgoing or SMTP server. But remember first email will deliver to your ISP's server then it will deliver to the destination. If you want to deliver directly your emails to the destination without using your ISPs SMTP server then you should configure your Windows 2000/XP as your own little SMTP server. It is much simple.

Steps
Control Panel
Add/Remove Programs
Add/Remove Windows Components (at left side)
Internet Information Services (IIS)
and finaly check on SMTP Service


After these steps Windows will ask Windows CD, Insert the Windows Disk in CD-ROM. It will install SMTP services in your Windows.

Now you can use your Windows as SMTP server. Goto your Outlook settings and change your SMTP/Out going server into localhost or 127.0.0.1

Enjoy your own SMTP server.

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Waht is Spam ?

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What is Spam?
It's a rare computer user who hasn't been bothered by Spam at some stage. By Spam, we mean unsolicited emails that try to sell you things of a dubious nature that you certainly didn't ask for and, in all probability, don't need. Everybody hates spam. It can clog up your email box, threaten the security of your PC, try to trick you into opening dangerous attachments, and even render the mail box entirely unusable. Here at Home and Learn, we've had to close down many email addresses due to spam. (We've only ever met one person who liked spam. This was a pensioner, new to email, who complained that something was blocking her advertisments. She wanted to know how she could get them back!)


How do the spammers get hold of my email address?
Spam can come from a wide variety of sources, and the spammers have many techniques to get hold of your email address. Here's just a few:

> From a web page
If you have ever posted to an online, public forum, and left your email address on the page, then it will almost certainly end up in the hands of the spammers. If you have your own website, and include your email address in plain text, then that will also get stolen by the spammers. In fact, anywhere on the web where you leave your email address is a source for the spammers. If you can see it, so can they.

The way they get the address is by something called harvesting. This is done with a piece of software called a Spider. The sole job of the Spider is to trawl through website looking for email addresses. Once the spammer has enough addresses, he (they are usally "he's") can sell them to third parties, and other spammers.

> From an infected PC.
A lot of viruses these days contain code to trawl through your email address book. These will then be sent to the spammer. If you have sent an email to somebody who is infected, and that person has you in his/her address book, then your address will be sent to the spammer.

> From YOUR infected PC
If you have a virus, the chances are that it will contain code to control your email. It will then contact another computer and receive a list of instructions, and email addresses. These instruction say something like, "Send the following email to this list of addresses". Your PC won't be sending out thousands of emails, but just a few. This is because your PC is just one of many thousand that are controlled by the same spammer (called a botnet). If your computer sends out just, say, 100 emails a day, then 100 times 1000 computers that the spammer controls totals 100,000 emails a day. If the spammer controls 10,000 computers then that's a million emails a day he can send out!

> Trial and Error
if you have an email address based on your name, and if your name is quite a common one, then the spammer will simply send out email trying to guess the first part. For example, suppose the end of your email address was "smith.co.uk" And you added "John" to the start, your email address would be easy to guess, and you'd have a very busy inbox indeed! If it was "john12_KJ876@smith.co.uk", it's unlikely the spammers could guess the first part.




Worst case scenarios
If your computer is infected, there could be another nasty side-effect - YOU get banned! Because your computer has been indentifed as sending out spam, you may well receive a message from your service provider telling you that your account has been suspended. You then have to go to the trouble of contacting your service provider, telling them that you're not a spammer, and asking what to do to get off their "bad books".

A more likely scenario is that your email gets bounced back to you by someone like SpamCop. The email will identify your IP address, and let you know that you're on a blacklist. SpamCop will keep you on the blacklist until it receives no more spam from your IP address in a 24 hour period. (It may not be your IP address but the address of your email servers. In which case, there's nothing you can do about it but notify your service provider. Your service provider will then totally ignore your call, and heap the blame on you!)




How to Defeat Spam
You can defeat spam (well, most of it). Here's a few ways.

Don't post your email address on a web page, unless you're disguising it in some way. As an example, an email address in this format is very difficult for a Spider to read, but quite easy for a human:
firstBit @ co. uk. homeandlearn (re-arange the ending)

Be wary of giving your email address to websites. Ask yourself, is there a privacy statement anywhere on the site? (Ours is here Privacy Policy) Can you easily opt-out if they send an email or newsletter to you? Do you trust them?
Never reply to a email sent to you by a spammer. If you do, you're telling the spammer that the email address is live and active - the very thing that he was looking for! (Remember: the spammer probably bought his list off someone else, and has no idea whether an address is active or not.)
Careful when opening attachments. Save the attachment to your hard-drive first, scan with your (up-to-date) Anti Virus software, and only then consider opening it. If you weren't expecting an email with an attachment, it's safer to just delete the entire email!
Set your email software to view message as text and NOT as HTML. In Outlook Express you can do this by clicking Tools > Options from them menu bar. From the Options dialogue box, click the Read tab. Put a tick in the box "Read all messages in plain text". The reason you'd want to do this is because HTML emails can be very helpful to spammers. They insert an image that tells them the email has been read, and thus that it's a live email box.
Consider getting some Anti-Spam software. The best of these are very good at detecing spam from the genuine emails. Here's two that Computer Shopper recommended in a recent review. (Dec 2006)
Allume SpamCatcher 4
Cloudmark
These both got 5 stars out of 5 in the review. The second one is only for Outlook or Outlook Express users. (Mcafee anti-spam got 4 stars out of 5, incidentally, and Norton only got 2!)


A good free anti-spam solution is SpamPal. This got 4 out of 5 stars, but Computer Shopper noted that it was a bit "clunky to set up".

But we recommend you start with the free software first, and test it out. If it's not catching at least 90% of spam coming in, then uninstall it and try something else!

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Waht is Spyware ?

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What is Spyware?
Broadly speaking, Spyware is something that sneaks on to your computer, usually with the intentions of extracting money from you. At its worst, Spyware can take control of your computer, directing you to web pages you didn't want to go to, downloading other nasty stuff in the background, and even harvesting email address, passwords and your credit card details. But even a mild case of Spyware infection can be nuisance.

If you've ever been plagued by annoying pop-ups when your computer loads, or have strange new icons where your clock is (bottom right, called the System Tray), or if you're directed to a strange webpage when you try to go on to the internet, then you may well be infected.

Spyware, in the main, gathers information about you and your online habits, and sends that information to third party. And all without asking for your permission!


Where does Spyware come from?
Spyware can come from a whole host of different sources. But Spyware mainly gets on to your PC through deception. For example, suppose you receive this email:




You'd assume that this email was sent to you in error. Can you resist clicking on the link? After all, what harm can it do? Well, a lot actually! There well may be a joke on the site, but there's something less funny going on in the background - the web page is trying to sneak something on to your PC! You may also have seen a harmless-looking popup window asking you to click a button to proceed. You'll click it anyway, just to get rid of it. Clicking OK is what's infected your PC!

Other sources of Spyware infection are freeware or shareware software, an operating system that is un-patched and hasn't got the latest security software, downloading stuff from peer-to peer applications - the list is long!

And don't think your Anti-Virus software will protect you - it won't! Spyware is not considered to be a virus, so your Anti-Virus software won't spring in to action once an infection takes place - it will stay sleeping in the background, unaware that anything malicious is going on. The best tool for the job is a dedicated Spyware Detection system.




Beware of the Scam Merchants!
You may have come across a website that promises to check your PC for Spyware infection. All for free. All you need to do is to click a button to scan your PC. So you download, scan, and lo and behold - it's found something! Then up pops a message directing you to a website that lets you buy the software.

Except, it didn't really detect anything. Or if it did, it's what's know as a false positive (Something that sounds dangerous but isn't). The job of the scan is to scare you into buying their software.

If you type in "Spyware detection" into Google, most of the results that come back are for these types of programmes. According to Suzi Turner, writing on Zdnet , some of the most popular Spyware scams are these products:

SpyAxe
SpySheriff
PSGuard
WorldAntiSpy
Spy Trooper
Razespyware
SpywareNo or SpyDemolisher
WinAntiVirus or WinAntiSpyware 2005
SlimShield tied with "Winhound Spyware Remover"
Spyware Bomber (shut down by the FTC)
Hopefully, you haven't bought anything on the top ten list! Even if you haven't, check out the alarmingly long list of scam Spyware on spywarewarrior.com (Fortunately, they also have a good-software list!)

If you've bought any of the software on the bad list then the protection you have is at no protection at all. At worst, these pieces of software can be incredibly difficult to get rid of - Spyware themselves!



How to get Rid of Spyware
As a computer owner, you really need your wits about you in the Spyware detection game. So what are you to do if you can't even trust the very people who say they are going to help you clean your PC? Well, you can fight back! The best way to do that is with software from very reputable companies. The following are the most well-known (and free) anti-spyware solutions:

Ad-Aware (SE Personal Edition)
SpyBot Search and Destroy
Microsoft Windows Defender
Ad-Aware is probably the easiest to use of the three. SpyBot is good, but a bit complex for beginners. Microsoft Windows Defender is well worth getting, too. However, it's not the easiest piece of software in the world to use. You do get some good tools with it, though. Check out the websites by clicking the links above (there's a tutorial on the Microsoft site for Windows Defender).

Once you download your chosen anti-spyware solution, you need to install it on to your PC. After you have installed it, start the software and do a full scan of your computer. (Ad-Aware has a nice big button that says "Scan"!)

Unlike anti-virus software, it IS recommended that you have more than one anti-spyware solution on your PC. This is because spyware can be very difficult to get rid of, and anti-spyware software will rarely find 100 percent of threats. By having more than one solution, what one piece of anti-spyware programme misses, the other should (hopefully) pick it up.

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What is a Trojan?

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What is a Trojan?
A Trojan is small, malicious programme that is installed along with a more attractive one. For example, that great freeware programme you got from that dodgy website? It may well be the programme you wanted. But someone (usually a 3rd party) may well have attached a Trojan to it. The Trojan will be installed as well as the software you wanted.

Trojans are not viruses, in the sense that they don't replicate or send copies of themselves to others. They are just another programme that can be installed on your computer, albeit a nasty one!



What do Trojans do?
A Trojan can be very malicious indeed. Most of them are intent on controlling your PC. These are called Remote Access Trojans, or RATs for short. If someone has placed a Trojan on your computer, they'll be able to see everything that you can. Some of them can even controll your webcam. That means the attacker can see you! If you have speakers attached to the PC, they can even hear you!

If that weren't bad enough, the attacker will have access to your computer, enabling him to upload nasty things to your PC. After all, why should he store these things on his computer when he has access to yours?

Most Trojans these days, though, are placed on your computer by criminals. If you type your credit card details in to a website, for example, then the attacker can record what you type. If a criminal has controll of a lot of computer, he could also launch something called a Denial of Service attack. A DoS attack is when a lot of malicious computers attack a particular network or website. The network has so many request that it can't cope, so has to shut down. The criminals then blackmail the owner ("We'll let you have your site back if you give us money".) Many gambling sites have been hit by this type of attack.

A Trojan can also disable your security software, leaving you wide open on the internet.


How do trojans get on My Computer?
If you have an unpatched version of a Windows operating sytem (XP, ME, W98, etc) that is allowed on the internet then you have a very high chance of becoming infected. Install Service pack 2 as matter of urgency. And get all the other Windows updates. If you browse using Internet Explorer then be aware that it is notorius for being unsecure. (At one stage, it was known as the Swiss Cheese browser because it had so many holes in it!) even with all the latest patches, someone is always trying to find a new hole in Internet Explorer. If an attacker can guide you to a particular website, then your browser's security holes can be a way for them to load programmes onto your PC. A lot of people have switched to using a browser other than Internet Explorer, the most popular choice being Firefox.

But Trojans can get on to your PC many other ways: email attachments, software/music downloads, unsafe Instant Mesaage clients, IRC, Peer 2 peer downloads, open ports not protected by a firewall - the list is long!



If I have Anti-Virus software, does that mean I am protected?
You are not necassirly protected from Trojans, just because you have Anti-Virus software on your computer. If you have Norton or Mcafee please remember this: Most popular does NOT mean best! (See our Anti-Virus section for more details.) The problem faced by the makers of Anti-Virus software is that Trojans are easily adapted, and new versions come out all the time. Anti-Virus software makers are constantly playing catch-up. That's why it's important to update your Anti-Virus software on a regular basis. Besides, a really good trojan can disable your Anti-Virus.



How Can I Protect Myself?
The best defense against Trojans is a dedicated Trojan scanner. There is a free online Trojan scan you can do here:

Free Trojan Scanner

Consider buying separate software just for Trojan protection. Not only will these detect the latest threat, but they will also rid your computer of any infection.

Trojans can be far more harmful than viruses, so it's well worth getting the right tool for the job. Don't skimp in this area!

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What is a firewall?

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What is a firewall (and why you need one)?
A firewall is protective barrier between you and the rest of the computers you are connected to. When you go on to the internet you are visible to the outside world. (If you weren't, then there would be no way to get a web page to your browser!) You are visible through something called a port. A port is service available to you. There are many thousands of these ports (services), and each is given a number. The three ports (services) you use most often are the world wide web (port 80), Incoming email (typically port 110), and outgoing email (usually port 25). The idea of a firewall is to close off the ports (services) you're not using. If you don't, then your open ports are an invitation to others to raid your computer! If you only have one piece of security software on your computer then it has to be a firewall. Unless your computer is not connected to the outside world, this is a must-have.


What kind of things can happen if I don't have a firewall?
If you do a fresh install of Windows XP, and leave it unpatched, your computer will be attacked within minutes. You'll be attacked through your open ports, and bombarded with popup messages; Trojans, viruses and worms will be loaded behind your back; Spyware and Malware will clog up your browser. In fact, PC Format magazine recently (issue 194) ran this very experiment. Their unprotected PC was unusable after about 2 and half hours! Having a firewall in place would have prevented some of these attacks. (But not all - XP should have Service Packs 1 and 2 installed before it's allowed on the internet.)

Even if you have all of XP's service packs and updates, not having a firewall means somebody will eventually find an open port on your computer. If they can install a Trojan on to your PC, they'll be able to control it! (See our Trojan section for more details on this topic.)



How Firewalls help protect you
Most firewalls, like the one built into Windows XP, will alert you about suspicious incoming traffic. Anyone trying to gain access to your PC will hit the firewall first. The firewall deflects the attack, and gives you a warning about it. But a good firewall like ZoneAlarm will also warn you about suspicious outgoing traffic (XP's own firewall doesn't do this). So the best firewalls do both - tell you about incoming and outgoing traffic.



The Types of Firewall
For the general user, you can place firewalls into two simple categories: hardware and software. A hardware firewall can be a router that sits between your computer and the outside world. You can plug more computers into the router, and each will be protected by the firewall that's part of the router.

A software firewall is one like ZoneAlarm. You install it on your PC, and it will hide open ports, deflect incoming attacks, and warn you about suspicious outgoing traffic. For added protection, you can have a software firewall on each computer that sits behind the router. An attacker would have to be very determined to get through your router's firewall and your software firewall!




Which firewall should I get?
If you have something like a wireless router then you'll probably already have a firewall. You should check your router's configuration pages to make sure it's turned on. (Some of them are actually turned OFF by default!) Once your router's firewall is turned on, you can install a software firewall on each PC that's connected to the router, just for added protection.

If you're not behind a router, then you need a software firewall. If you have Internet Security software like Kaspersky then it will probably include a firewall as well. You should check, though. If you haven't got any Internet Security software then we highly recommend the free version of ZoneAlarm. This piece of software has been available from ZoneLabs for some time, and has a very good reputation.

Home and Learn Recommended Free Firewall: ZoneAlarm Basic


But to recap: If you don't have a firewall, and your computer is connected to the Internet,

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What is Virus ?

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What is a Virus?
A computer virus is a programme, or piece of code, that is written to interfere with, and harm, your machine. A virus can replicate itself, spread to other computers, and attack other programmes on your computer. (By attack, we mean change or delete files.) Computer experts distinguish between a virus, a worm, and a Trojan. Here's the differences:

Virus - Can replicate and spread to other computers. Also attacks other programmes
Worm - A special type of virus that can replicate and spread, but generally doesn't attack other programmes
Trojan - Doesn't replicate, but can spread. Doesn't attack other programmes. Usually just a way of recording and reporting what you do on your PC
Viruses are split into different categories, depending on what they do. Here are a few categories of viruses:

Boot Sector Virus
The Boot Sector of a PC is a part of your computer that gets accessed first when you turn it on. It tells Windows what to do and what to load. It's like a "Things To Do" list. The Boot Sector is also known as the Master Boot Record. A boot sector virus is designed to attack this, causing your PC to refuse to start at all!

File Virus
A file virus, as its name suggests, attacks files on your computer. Also attacks entire programmes, though.

Macro Virus
These types of virus are written specifically to infect Microsoft Office documents (Word, Excel PowerPoint, etc.) A Word document can contain a Macro Virus. You usually need to open a document in an Microsoft Office application before the virus can do any harm.

Multipartite Virus
A multipartite virus is designed to infect both the boot sector and files on your computer

Polymorphic Virus
This type of virus alter their own code when they infect another computer. They do this to try and avoid detection by anti-virus programmes.



How do Viruses get on my computer?
The most common way that a virus gets on your computer is by an email attachment. If you open the attachment, and your anti-virus programme doesn't detect it, then that is enough to infect your computer. Some people go so far as NOT opening attachments at all, but simply deleting the entire message as soon as it comes in. While this approach will greatly reduce your chances of becoming infected, it may offend those relatives of yours who have just sent you the latest pictures of little Johnny!

You can also get viruses by downloading programmes from the internet. That great piece of freeware you spotted from an obscure site may not be so great after all. It could well be infecting your PC as the main programme is installing. And if you or your children download software from peer to peer networks (like Kazaa, Morpheus, Shareaza) then you could be downloading more than you bargained for!

If your PC is running any version of Windows, and it hasn't got all the latest patches and updates, then your computer will be attacked a few minutes after going on the internet! (Non Windows users can go into smug mode!)



Could I be infected by a Virus?
If you are infected by a virus, your computer may exhibit some well-known symptoms. Here's a few signs that you may be infected:

Your computer starts running more slowly than it usually does
Your computer keep crashing
Your computer keep crashing and then restarting
Programmes you normally work with suddenly start behaving oddly
You can't access your disk drives
Other symptoms to look out for are strange error messages, documents not printing correctly, and distorted menus and dialogue boxes. Try not to panic if your computer is exhibiting one or two items on the list.

The first thing to do is to scan your PC with your (up-to-date) anti virus software. If your anti-virus software fails to detect anything, then that doesn't mean you're NOT infected - it may just be poor anti-virus software. And remember, most popular doesn't mean most effective. While Norton and Mcafee are good, extensive tests in respected computer magazine show that they are not the best. Not being the best means that they may fail to detect the virus on your PC! Not only that, Norton and Mcafee are becoming really expensive to maintain!



Free Anti-Virus software
There are some good free anti-virus solutions out there. The most popular is AVG. This has gotten results that are as good as the market leaders. You can check it out here (this page also tells you what you DON'T get with the free edition):

AVG Free Edition

Once installed, AVG will update itself on a regular, daily basis. It will also scan emails for viruses, and alert you if it finds anything. The interface is a bit old-fashioned but, hey, it's free and it does a quite a good job!

Another good solution is AntiVir from Avira. The classic edition is free, as well. Check out their website here:

Avira AntiVir Personal Edition Classic

AntiVir will also protect users of non Microsoft computers (Linux/FreeBSD/Solaris). It is, of course, debatable whether you need anti-virus protection if you don't have a Windows machine!

NOTE: If you're changing AV software, you MUST make sure that the old one has been completely uninstalled first. Norton and Mcafee can be difficult to uninstall, and you should consult their website BEFORE uninstalling - they may even have a special tool to do the job. Some people have said that trying to uninstall Norton or Mcafee was worse than getting a virus. (If you see an ad below for either of these two - it's not because we chose it!)

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What is Network ?

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The word network can be used to describe a very large and complicated set of equipment. In its most accurate and simplest definition a network refers to the cables and electronic components that amplify the signals going through the cables. The amplifying equipment is necessary to ensure accurate communication and make the signal stronger if it needs to go long distances.

Broader Definition
When many people talk about a network, they are talking about a network using a very broad concept. For instance if someone cannot get to their email, they may say "the network is down". Likewise they may say this if they cannot surf the internet or get to their files. They may not stop to think that in each specific instance there is a single piece of equipment that may provide the capability which they are trying to use.

Most people who work on a corporate or organizational network think about the network in component parts. The three main parts are:

The cabling and amplifiers mentioned in the first paragraph.
The workstations which most members of the organization use to access resources.
Higher powered computers called servers - These are the machines that provide what network administrators call services. Services include the functions that most people try to use such as email, reading and writing files, printing, and getting to the internet. Whenever a user is trying to do something on the network, there is a service or machine providing the capability to do so. This even includes times when someone is trying to get to network resources from their home.


Services
Services include:

Email service
File service - Allows users to use and share file space on a computer with a lot of file space.
Print service - Allows printing to printers connected on the network.
Web surfing - Allowing someone to open web pages and see web sites on the internet.
Filtering out undesired sites on the internet.
Allowing someone to access the network from the outside (from home).
Updating virus definitions on workstations.
Allowing someone to log onto the network.
Even giving a workstation an address on the network is a service. If your computer does not have an address, it cannot access the internet or any other resource on the network.
A Typical Network
A typical corporate or organizational network is shown below:



Of course there are variations on this network layout and some details have been left out for the sake of simplicity but this drawing should give you some idea about what goes on behind the scene on the network at your organization. Some servers and server functions have not been shown here.

The firewall is the device that protects all computers in the network from many attacks. It allows some types of network traffic into the network from the outside, but usually only for mail or web services. Usually the internet traffic that that is allowed to come into the network is routed to the part of the network labeled "DMZ" on the right side of the diagram. DMZ stands for demilitarized zone and is also called a semi-private network. In this DMZ is a web server which is used to allow people surfing on the internet to see web pages posted by the organization. A mail server is also shown in the DMZ but this could be replaced by a mail relay server while the mail server is placed inside the private network. The mail relay server would forward mail traffic from the outside to the mail server. This would increase the security of the network since a direct connection from the internet to the mail server would not be allowed.

The private network is of course the most secure part of the network. There are several servers on this network including:

A login server (called a domain controller) which controls everyones permissions and access to the network resources such as files. Without this server, they cannot login to the network.
An address server (called a DHCP server) which provides addresses to computers on the network so they can communicate as discussed earlier.
A file server which provides common files and a private folder for users.
A remote access server which allows users to connect to the network by telephone from the outside.
Also the workstations are part of this network.

Conclusion
Knowing the above information, if someone cannot get their mail, they may think the network is down. This is not likely to be the case. The mail server may be down but the network is not likely to be down. The same goes for when someone can't surf the web. There may be a problem with the firewall or the line connecting to the internet, but it is unlikely that the whold netwlrk is down. When problems are noticed it is best for the user to describe what they were trying to do and what happened.

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What is a RootKit

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What is a RootKit?
A rootkit is a programme, script or set of software tools that allows an attacker full access to your PC or network. By full access, we mean administrator-level access. A rootkit is really the technique for getting harmful things like Trojans, Spyware and Viruses on to a system.



Why are RootKits so dangerous?
The main form of an attack for a rootkit is stealth. They will hide away, deep in the recesses of your computer. Because they have administrator-level access they can do things like hijack your Windows searches and hide any information about the RootKit, control your Anti-Virus software and tell it to ignore the RootKit, hide from the list of active processess. And a whole lot more besides!

The most famous RootKit was one that was installed by some Sony audio CDs. Sony hid a RootKit on people's computer as part of its Digital Rights Managment strategy. This gave them effective control of a user's PC. A security expert called Mark Russinovich (of Sysinternals) discovered the Sony RootKit, and it made the news the world over. Sony had to issue a download so that people get the RootKit off their computers. They also recalled all the music CDs that had the RootKit software.

It's the fact that RootKits are so difficult to detect that makes them dangerous.


How do I know if I'm infected?
With great difficulty is the answer to this one! Don't expect your Anti-Virus software to help you out here. The very best RootKits can easily defeat Anti-Virus software, so you need a specialist tool for this job. There's a really good website that explains in more detail just what a RootKit is. They also have links to some free RootKit Detection tools.

Free RootKit Detection Tools

We highly recommend you pop along to this website, and get your PC checked for RootKits.

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What is a Firewall?

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The term "firewall" illustrates a system that protects a network and the machines on them from various types of attack. Firewalls are geared towards keeping the server up all the time and protecting the entire network.The primary goal of a firewall is to implement a desired security policy; controlling access in both directions through the firewall, and to protect the firewall itself from compromise. It wards off intrusion attempts, Trojans and other malicious attacks.Personal Firewalls:They are meant for the home user in a networked environment. They aim to block simple attacks, unlike the enterprise level firewalls that the corporate world uses at the server or router end. There are many ways to implement a firewall, each with specific advantages and disadvantages.Are they really needed?Nowadays organizations and professionals use Internet technology to establish their online presence and showcase their products and services globally. Their endeavor is to leverage digital technology to make their business work for them.All the organizations and professionals are shifting from Dialup to broadband and getting a fixed IP. It has led to an increase in security attacks, bugs in everyday working. This does not mean that Dialup being anonymous dynamic link or the firewall of the ISP network make you pretty safe.Now if your machine was under attack, you must have wondered what went wrong making your system crash suddenly. So I would rather like to say, it’s not necessary for anyone to actually know about you or your IP address to gain access to your system.If you system is infected or prone to intrusions, then beyond the anonymity of your Dialup connection or a dynamic IP, your system can be hacked.Types of AttacksIntrusion:There are many ways to gain unauthorized access to a system. Operating system vulnerabilities, cracked or guessed passwords are some of the more common. Once access is attained, the intruder can send email, tamper with data, or use the system privileges to attack another system.Information Theft and Tampering:Data theft and tampering do not always require that the system be compromised. There have been many bugs with FTP servers that allow attackers to download password files or upload Trojan horses.Service Attacks:Any attack that keeps the intended user from being able to use the services provided by their servers is considered a denial of service attack. There are many types of denial of service attacks, and unfortunately are very difficult to defend against. "Mail bombs" are one example in which an attacker repeatedly sends large mail files in the attempt at filling the server’s disk filesystem thus preventing legitimate mail from being received.Types of AttackersJoyrider:Not all attacks on computer systems are malicious. Joyriders are just looking for fun. Your system may be broken into just because it was easy, or to use the machine as a platform to attack others. It may be difficult to detect intrusion on a system that is used for this purpose. If the log files are modified, and if everything appears to be working, you may never know.Vandals:A vandal is malicious. They break in to delete files or crash computer systems either because they don't like you, or because they enjoy destroying things. If a vandal breaks into your computer, you will know about it right away. Vandals may also steal secrets and target your privacy.“In an incident a Trojan was being used to operate the web cam. All the activities being done in the house were being telecasted on the websites.”Spies:Spies are out to get secret information. It may be difficult to detect break-ins by spies since they will probably leave no trace if they get what they are looking for.A personal firewall, therefore, is one of the methods you can use to deny such intrusions.How Firewalls work?Firewalls basically work as a filter between your application and network connection. They act as gatekeepers and as per your settings, show a port as open or closed for communication. You can grant rights for different applications to gain access to the internet and also in a reverse manner by blocking outside applications trying to use ports and protocols and preventing attacks. Hence you can block ports that you don’t use or even block common ports used by Trojans.Using Firewalls you can also block protocols, so restricting access to NetBIOS will prevent computers on the network from accessing your data. Firewalls often use a combination of ports, protocols, and application level security to give you the desired security.

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What is Internet?

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The word internet is used to describe a network of networks which incorporate a very large and complicated set of equipment. To understand the internet, there are three areas of discussion which are very helpful. These include the various services provided across the internet, the functions that enable the internet to work, and the various organizations that are part of the internet.

Internet Services
The main services used on the internet include:

Web browsing - Supported by the HTTP protocol, this functions allows users to view web pages using a web browser.
E-mail - Allows people to send and receive electronic messages.
Other lesser used services include telnet (allows remote login to computers), FTP (Allows quick file transmission to remote computers), and gopher (An early form of text based form of reading internet documents which is rarely used today).

Internet Functions
The internet provides for the following two functions which support communications. Without the communications support mentioned below, the internet could not function. These two functions are provided by internet service providers listed below under the "Internet Organizations" header.

Physical lines that data is sent across.
Routing of data - There are special machines on the internet called routers, that determine where data needs to go to get from the sender of the data to the receiver of the data.


Internet Organizations
ISPs (Internet Service Providers) - They provide the connection to the internet for users and also provide routers that direct internet traffic.
Corporations or Web hosting providers with mail servers and web servers - They provide the information posted on the internet and virtual data connections to other mail servers.
There are also other organizations that regulate the internet, providing communication standards and designing new communication standards for improvements. These communication standards are also known as protocols.

Summary
So the internet is a collection of organizations that provide equipment that support the internet functions and services. The internet connects many corporate and organizational private networks together thus enabling all these organizations to easily communicate.

Accessing the Internet
People use an internet browser to access web pages that are available across the internet. Internet browsers include Microsoft Internet Explorer, Netscape Navigator, Mozilla, and others.

Web pages are created in a marked up form of text file called HTML (Hyper-Text Markup Language). The markup within the text indicates document structure showing where paragraphs begin and end, what items are in a list, headers, tables and other document structure.

When people are browsing of surfing the internet, they usually go from place to place by clicking on links. These links are locations for specific pages and indicate the three things:

Protocol being used such as http or ftp
The domain that the web page is found on. This will point to a specific organization's or company's web server.
The location of the page on the server including the directory path and file name.
An example link is "http://www.comptechdoc.org/basics/bastutorial/osintro.html". In this case http is the protocol being used, the comptechdoc.org domain indicates where the organization's web server is, and the "/basics/bastutorial/osintro.html" part of the string indicates the folders the file is in and the name of the file.

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