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Web Hosting ExplainedSimply put web hosting, or web site hosting, is the process of creating an internet web site and allowing others around the world to view the web site. A web hosting provider is basically a business which rents space on its computers (commonly these computers are called servers.) What happens is that after a web site is created, it is uploaded or transferred to the hosting provider's server. The hosting provider then allows the world to view the web site when someone types in the web address (or domain name) of the internet site. And then the site (or specifically the page) is sent to the person requesting to view the site. Essentially, web hosting can be defined as providing space on a server which allows others to view your web site. How it works When a site is on the server it is controlled by the software on the computer; i.e., the server software. Currently over 60% of all servers on the internet use the server software known as Apache server. What happens is that when a web site is created on the server, the server software is told where the web site is on the hard disk and the details of the account. Then when a user types in a domain name (web site address) and requests a specific page from their internet browser, that request is sent to the web hosting provider's server where the web site is located. The server software then finds the specific site and page requested in its list of details, and figures out which page the user wants and then sends that page to the user's internet browser where the page is displayed. Basically, the server software is the intermediary between the files on the server and the browser requesting the web pages. Server software can process millions and millions of requests each day. Different web page endings explained: .htm, .html, .asp, .php, .cgi, .pl, .aspx Surf around the web for a while and you will notice that some of the web pages that you view have different file extensions. For example, this web page is titled web-page-extensions.htm. It could have been titled web-page-extensions.html though. So what is different between all of these extensions? Is a .asp better or worse than a .cgi extension? Or is everyone just being creative? When your internet browser requests a web page from a web host it examines the file extension. If the extension is hyper text mark up language (.htm or .html) then it is rendered in your browser. If the extension is something else then, depending on what the extension is, the server software does something to the page and then sends you the page. What the server software does depends on what is written in the web page. And frequently the web pages are running programming scripts or mini-computer programs which are processing data before or after you arrive. For example, if you have ever been to a web page which displays the IP address of where you are (an IP address is a numerical address of your computer on the internet), chances are the web page is a .php extension. Why? Because using the PHP language it is very easy to display this. To see an example try this. What happens when you request the page with the .php extension is that the server software runs a computer script (a PHP language script in this case) and before the web page is displayed in your browser, it adds the results of the computer script. So the .php extension allows a web page to interact dynamically with each person visiting the site. Thus, each time someone visits the IP Address .php page they will see something different because the IP address of their computer is different from yours. Some of the different extensions you will see are as follows: .php (Hypertext Preprocessor Lanugage: Scripting language
in the web page itself) So every time you see a web page with a different extension other than .htm or .html you know more is going on. CGI and Perl - Explained CGI (Common Gateway Interface) is a very common word when web hosting is mentioned. Frequently, but incorrectly, people usually asked web hosting providers if they can run CGI scripts on their accounts. What they are actually asking, albeit indirectly, is if they can use CGI to run computer programs on their website. CGI, in simple terms, is essentially an intermediary between the a computer script and the web site. It operates to take the information from the web page and pass it to a computer script (program) and do whatever the computer program says to do. CGI is not a computer language per se, but a common language for different computer programs to interact with the web pages (hence Common Gateway Interface). One of the recognized, and highly used, computer program languages which uses CGI is Perl. Perl is a high level computer language which can manipulate files, text and perform system operations with ease. Perl scripts are highly used on the web and quite frequently you hear about a very common perl script known as "formmail." A formmail script is essentially a computer program written in Perl which takes information from a web page and e-mails the information to someone. This is accomplished when someone fills out a form on a web page and presses a button. The button then starts the computer program (formmail) which uses CGI to get the information from the webpage and e-mails the information. Perl scripts have been written to do quite a lot of things on a web site and it is a very powerful language. But, it is not the only computer language which can interact with a web page. Some others are ASP, PHP, C, Python, etc. Firewalls - Explained A term you hear often is "firewalls." But what is a firewall? A firewall is a wall between two rooms or spaces which prevents, or hopes to prevent, fire from spreading from one room to another. So if one room catches on fire the fire will not be able to breach or break through the firewall to reach and damage the other room. Firewalls are not absolute barriers but serve to prevent most openings or slow the fire's damage. A firewall on the internet is simila - it serves to prevent one computer from compromising another computer. There are two types of firewalls used currently: software and hardware. A software firewall is a computer program running on a computer which performs its duties on that computer. We will discuss its duties in a moment but now realize that a software firewall is just bits of code on a computer. A hardware firewall is a physical piece of equipment designed to perform firewall duties. A hardware firewall may actually be another computer or a dedicated piece of equipment with its only function being serving as a firewall. So what does a internet firewall do? The reality of the situation is that it keeps out malicious hackers and people who seek to do damage and/or take over other peoples' servers. Firewalls really serve no other purpose. Firewalls seek to limit the access to a server or computer and let in only the people who need to be there. Firewalls also attempt to limit the impact of computer viruses from spreading and preventing individuals from running a DOS attack. (A DOS attack is a Denial of Service attack which attempts to stop the server from responding or running on the internet by flooding it with millions of attacks.) By having a good firewall you eliminate some risks with a computer on the internet and hopefully keep out the malicious people. Will a firewall guarantee that a server will not be compromised? No, but like a real firewall, it does slow the fire, or in this case the attacks, so they can be dealt with before the real damage is done. Firewalls constantly have to be tweaked or fine-tuned to keep out the latest tricks and traps set by the hackers. Root Access - Explained A lot of times people want hosting with access to root. But what does "root access" mean? Root, or getting root, is receiving the privledge to access all of the places on a computer. If you think of a server/computer as a tree the roots control the tree. The roots of a tree allow water in, minerals in and are the lifeblood of the tree. Anything which goes into the roots goes into the entire tree. Anything which affects the roots of a tree affects the entire tree. Servers are set up with a similar thought process in that parts of the server are broken down into different areas. Each different area has its own privledges. One area cannot affect another area. For example, if there are three web sites on a server and one web site breaks the other two will not be affected. Each web site is in its own part of the server and can affect only itself. However, there has to be a master account or way into each area or site. If you don't have a master method to access all sites at once it would be a tremoundous amount of effort if something needed to be fixed or updated on every site on the server. The method or access to all of the parts of the server is "root access." When someone has root access they can affect everything on the entire server or change everything on the entire server. There are no restrictions with root access. If an error is made in root access it could wipe out the entire server. So why do people want root access? Who knows. But unless you are leasing your own server and need to affect every account on the server you don't need root access. There are some things you can do to make your site run more efficient with root access, but unless you know what you are doing you could destroy the entire server. And webhosting providers are not going to allow that to happen because chances are there is more than one client on the server. Besides that's what the webhosting company is being paid to do - manage the server where your hosting account is. It's not your job to manage the server, just to manage your own web site. SSH - Explained (Secure Shell Access) What is SSH and why would you want it? SSH stands for Secure Shell or Secure Shell Access. SSH is basically a non-graphical (for the most part) connection between two computers. Secure Shell Access is the more secure form of Shell Access made popular by Unix computers. In the past when someone wanted to access files from one computer to another they would have used a connection known as a shell connection. So by using this shell connection on one computer you could see exactly what was happening on the other computer. One computer was just a shell of the other. Telnet is a shell access between computers. As computers became more and more advanced so did the methods of accessing them. And as Linux computers once came from Unix (at least the main concepts) the idea of connecting one computer to transferred. As graphical interfaces among computers grew you would expect that a command line non-graphical connection to be left behind. This is not so with SSH because while graphics make it easy to work on a computer the connections between two computers must be very fast in order for a graphical connection to work well. Because not all connections are very fast SSH maintains some popularity. SSH is the equivalent of working in DOS. You only get words and lines. And generally you have to know the unique commands to the SSH because there is more than one version. So why would you want to use it? It depends - if you are comfortable in working in text-based screens and you know the SSH commands you can run one computer from another pretty easy. You could literally remotely control a computer from another place in the world. If it sounds so good, why doesn't everyone have access like this? The main reason most web hosting companies don't allow SSH connections is that while they may seem secure SSH connections leave a server open to security issues. And basically you can run one computer from another--this is highly desirable for a hacker. Recently there was a very large security breach which allowed hackers to take control of servers if the servers allowed SSH connections. Further, there are methods to intercept SSH connections and allow another person into your files or the server if using SSH. And every SSH connection allowed is a potential access hole for a hacker. If you have 300 people using SSH on a server you are potentially allowing 300 more entry points for hackers. Therefore, for security reasons most web hosting companies do not allow SSH access. SSL - Explained SSL stands for Secure Sockets Layer. What this means in plain language is that when a Internet Browser connects to a server connected to the internet the transfer of data between the browser and the server is encrypted. The data is encrypted so no one who is possibly intercepting the data transfer between the two can read it. So while a person can intercept the data transfer they won't be able to read the data because it will be gibberish to them. To use SSL there must be several requirements met first. The first requirment is that the Internet Browser be cabable of handling SSL communications. This generally isn't a problem with most of the commercially available browsers nowdays. The second requirement is that the server must be set up with a certificate which allows SSL communications. This SSL certificate is set up by the web site owner. SSL encryption comes in two versions 56-bit encryption and 128-bit encryption. The higher the number the better the encryption. So where can you get a SSL certificate for a web site? You can get them in several places. First, the web site can just create their own certificate. There is nothing wrong with doing so, but in doing so when a person visits the web site the visitor might get a warning that the certificate isn't trusted. This is because the person just created it and did not go through one of the commercial entities providing certificates, which are considered trusted. If a web site owner gets the certificate from a commercial entity (for a cost of course) these entities will verify the site owner and the warning will not generally appear. To use the SSL encryption the person visiting the website must use the "https" protocol. Normally, if you look at a web site address you will see the address as "http". This page's address is "http://www.e3servers.com/articles/ssl.htm". At the front of the address is http. If we were to use encryption for a web page we would use the https instead of https. The "s" stands for secure. It is only when you use https you know the web page you are viewing is encrypted with SSL. To see a SSL encrypted page look at this page. With some browsers you might see a gold lock on the bottom of the browser indicating that the browser is viewing a SSL encrypted page. However, the absence of a gold lock or the presence of the gold lock DOES NOT absolutely mean that the page is SSL encrypted. ONLY if the address starts with https can you be sure of the encryption. This is because sometimes there are items written in the web page which indicate to the browser that the page isn't encrypted when in fact it is. SSL encryption is used primarily for e-commerce applications. While not all communications between a browser and server are intercepted you never want to take a chance when you are submitting to a web site information concerning your credit card, home address information and/or any personal information. Without SSL encryption every time you ordered something online you might be giving out your credit card number to a thief. Without SSL encryption there would be no e-commerce. A common question is that if a site uses SSL encryption is the information safe when data arrives at the server? No. SSL encryption only makes the data transfer difficult to read. Once the data arrives either at the browser or at the server it is no longer encrypted. That's why there are firewalls and other items used to protect servers and computers attached to the internet. Protecting information on the net relies on several things and SSL encryption works only on the flow of information not the storage of information. Static IP and Shared IP - The Differences One term you see tossed around a lot in web hosting is IP addresses. There are basically two types of IP addresses: static and shared. Before the difference between the two is discussed, the definition of an IP must be discussed. When someone types in the address: www.yourdomain.com that name is translated into numbers (called an IP address) and then the computer is directed to that IP address which is the web site. Every web site on the internet is found not by its domain name but by its IP address. IP addresses are in the format similar to 192.168.0.1, four discreet blocks separated by periods. You can reach a site by typing in the IP address alone and that will take you directly to the site. For example www.e3servers.com resolves (turns into) 64.191.62.74. So if you type in 64.191.62.74 directly into the address bar of your browser you will arrive the home page of this website. Now every single website has an IP address specifically allocated to it. For example, every single website on this server does not use different IP addresses. If every site used a different IP address there could potentially could be a problem with running out of IP addresses. (Fortunately this is not a problem and is going to be resolved when a new IP address standard is fully adopted). A lot of the sites on this server, and other servers on the internet, use one IP address for multiple sites. So you might see joeswebsite.com and marywebsite.com using the same IP address. Using more than one IP address frees up IP address which are a limited resource. Basically what happens is that when joeswebsite.com is resolved into the IP address, the person looking for joewebsite.com arrives at the server; the server then realizes that the person is looking for joeswebsite.com and sends that page to the person requesting it. The server basically steps in and does a millisecond of work and saves an IP address. Using more than one site on an IP address is called sharing IPs or a Shared IP address. If a site has its own IP address, and shares with no one else, it is called a Static IP address. You can always reach a site which has a static IP address by using its IP address alone, but you can't reach a site using a shared IP address by typing in the IP address alone because when you type in a shared IP address you arrive at the server but the server doesn't know which site you want because you haven't told it which domain name you want. So looking at our example above, we typed in 64.191.62.74 and arrived at www.e3servers.com we know that only www.e3servers.com uses this address because we can get to site without typing in a domain name and thus it must be a static IP address. But why do you need a static IP address? The main reason for having a static IP address is that you can only use SSL encryption (the stuff that makes e-commerce happen) on a static IP address. In order for a person to transmit sensitive data over the internet at times this data must be encrypted to prevent someone from intercepting the information. You can only use this encryption (called SSL) when the web site has its own IP address (static IP). It doesn't work on a shared IP. So when www.e3servers.com takes in order with a person's credit card it needs to encrypt this data and it uses SSL with its static IP. Another reason for having a static IP address is that if a web site wanted to have anonymous ftp transfers (basically where anyone can download files off a site) the site needs to have a static IP address to handle the anonymous ftp transfer. Other than these two reasons there is no need for a site to have its own IP address. DNS Propagation - Explained Why does it takes up to 72 hours for youe site to be visible Once the account is set up on a server the "nameservers" for the domain hosted on the server must be changed. Nameservers are the internet's way to direct someone to your site. When someone types in the address: www.yourdomain.com that name is translated (or resolved) into numbers (called an IP address) and then the computer is directed to the correct site using those numbers. The translation of a domain name to an IP address is done through nameservers. Nameservers are handled by a domain registrar - the place where the domain name was registered. Once the nameservers have been updated at the domain registrar it takes up to 72 hours for this information to filter through the internet. What happens is that your domain registrar submits this information to the master record database and it is available there very soon. However, each ISP (the way you access the internet) does not use the master record every time they need to find a domain name. What the ISPs do is copy the master record and then have their own database of nameserver information. When someone on their ISP looks for a domain name they are given the information in their database not necessarily the up to date master record. The problem comes due to the fact that each ISP updates their database with the new information whenever they want to. Some do it every night, some every other day and some up to 3 days. So even though you made the nameserver changes it *depends* on when your ISP (not your host!) updates the info in their database, which can take up to three days even though your account is activated right away. This does not mean you cannot access your account and transfer files - you can do that right away as well as set up all of your mail accounts and more, but until everyone updates to the new records some people might not find your site. The process of this filtering of the master record through the internet is called DNS propagation. WebMail - Explained One of the features which is being offered by some hosting providers is Webmail. But what is Webmail and is it useful to you? Before we talk about Webmail let's look at email. Email is one of the most useful tools of having a hosting account. It allows you to send and receive messages to anyone on the Internet in just a minute. You can attach documents to e-mail, you can send files with e-mail and a whole lot more. Usually to send or receive a message in e-mail you configure or setup a computer that you are using on a regular basis to handle your e-mail. This computer you use is programmed with the settings of your e-mail account. When you want to send a message you will open your e-mail program (Outlook, Pegasus, etc.) and type in your message. When you want to read your e-mail you will look in your inbox on this computer. All your e-mail is handled from this computer. But what if you need to send a message and you are not at your computer? This is where Webmail comes in. Normally if you are not at your computer which handles your e-mail you can't send or receive e-mail. Now if you have access to another computer you could then set up that computer to send and receive your e-mail as well. But what if you travel? Do you want to set up every computer you come along to handle your e-mail? No. That's where Webmail comes in. Webmail allows you to access your e-mail account wherever you are in the world and whenever your want. All you need is a computer with Internet access. You don't have to configure anything. To access your Webmail all you do is type in your website address something like: http://webmail.mysite.com or http://www.mysite.com:2095. (What you type depends on what version of Webmail you have; your host can provide you with your correct address.) When you type in your Webmail address what happens is that you open a program on the server your account is hosted on and Webmail accesses your e-mail account. From the Webmail program you can read your e-mail, send an e-mail, modify your address book, send a file - everything you can at home or work with your computer you can do with Webmail. If you have ever used an account like Hotmail or Yahoo Mail - Webmail is the same thing. But instead of setting up a entirely different account with Hotmail, or Yahoo, you can use your e-mail account with your website. This allows you to have 24/7 access to your e-mail account anywhere you are in the world, as long as you find any computer hooked up to the Internet. A very useful feature indeed. Web Hosting Explained |
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