proxy-server

What is a Proxy Server?
A Proxy server is an intermediary machine, between a client and the actual server, which is used to filter or cache requests made by the client.

This article is focused on the Different Caching Web Proxies.

Normal (Regular/Caching) Proxy:
A regular caching proxy server is a server which listens on a separate port (e.g. 3128) and the clients (browsers) are configured to send requests for connectivity to that port. So the proxy server receives the request, fetches the content and stores a copy for future use. So next time when another client requests for the same webpage the proxy server just replies to the request with the content in its cache thus improving the overall request-reply speed.

Transparent Proxy:
A transparent proxy server is also a caching server but the server is configured in such a way that it eliminates the client side (browser side) configuration. Typically the proxy server resides on the gateway and intercepts the WWW requests (port 80, 443 etc.) from the clients and fetches the content for the first time and subsequently replies from its local cache. The name Transparent is due to the fact that the client doesn’t know that there is a proxy server which mediates their requests. Transparent proxy servers are mostly used in big corporate organizations where the client side configuration is not easy (due to the number of clients). This type of server is also used in ISP’s to reduce the load on the bandwidth usage.

Reverse Proxy:
A reverse proxy is totally different in its usage because it is used for the benefit of the web server rather than its clients. Basically a reverse proxy is on the web server end which will cache all the static answers from the web server and reply to the clients from its cache to reduce the load on the web server. This type of setup is also known as Web Server Acceleration.


What is a Proxy Server
I. What is a Proxy Server – Brief Introduction

A proxy server is a computer that acts as an intermediary between the user’s computer and the Internet. It allows client computers to make indirect network connections to other network services. Client computers connect to the proxy server, requesting some resources like web pages, games, videos, mp3, e-books, any other resources which are available from various servers over Internet. As soon as getting such request, the proxy server will seek for the resources from the cache in its local hard disk. If the resources have been cached before, the proxy server will return them to the client computers. If not cached, it will connect to the relevant servers and request the resources on behalf of the client computers. Then it ‘caches’ resources from the remote servers, and returns subsequent requests for the same content directly. A proxy server may optionally alter the clients’ requests or the servers’ response for some potential purposes.

II. What is a Proxy Server – Benefits

Now you know what is a proxy server and how it works, then why people use it? That’s because it has a variety of potential purposes, such as:

To hide the IP address of the client computer so that it can surf anonymous, it’s mostly for security. Fox example, if a client visit yahoo via a proxy server, yahoo will get a request from the proxy server but not this client which makes it difficult for yahoo to track the client.
To speed up Internet surfing. All requests from client computers will reach the proxy server at first. If the proxy server has cached the required resources in its local hard disk before , clients will get feedback directly from proxy server, it will be more quickly.
To block undesired sites – black list, permit only authorized sites – white list, or some other access policy. Many work places, schools, and colleges restrict the web sites and online services by proxy server according to either sites’ URL or content.
To bypass security restrictions and filters. For example, many work offices have blocked facebook and myspace however, via a proxy server you will be able to access blocked websites easily.
To scan outbound content, e.g., for data leak protection.
To circumvent regional restrictions. For example, a server using IP-based geolocation to restrict its service to a certain country can be accessed using a proxy located in that country to access the service.

III. What is a Proxy Server – Types

There are many different types of proxy server and here are some common types:

Anonymous Proxy – Anonymous proxy servers conceal your information. When you go to request something from the webpage, the webpage gets the IP address of the proxy server that you’re using instead of your own. The server has no way of accessing your IP address and communication between you and the proxy server is encrypted, in cases where the greatest deal of security is desired.
High Anonymity Proxy – This type of proxy server does not identify itself as a proxy server and does not make available the original IP address. High anonymity proxies, only include the REMOTE_ADDR header with the IP address of the proxy server, making it appear that the proxy server is the client.

Transparent Proxy – An example of a transparent proxy would be a server that simply forwards your request to the resource that you want without concealing any of your information. This may be used in the workplace, where the IP address of the request is revealed to the server being requested from but where the proxy provides access to the resource for a multitude of computers within the network. Transparent proxies are generally not what people are looking for when they go shopping for proxy server access online.

Reverse Proxy – A reverse proxy server is generally used to pass requests from the Internet, through a firewall to isolated, private networks. It is used to prevent Internet clients from having direct, unmonitored access to sensitive data residing on content servers on an isolated network, or intranet. If caching is enabled, a reverse proxy can also lessen network traffic by serving cached information rather than passing all requests to actual content servers.

IV. What is a Proxy Server – Build Your Own Proxy Server
CCProxy is an easy-to-use proxy server software based on Windows. It provides 3-user free version for personal users and home users to build their own proxy server efficiently and easily, bellow is a step by step instruction for you.

Before proceeding, let’s say that you want to build a proxy server with LAN. If you want your proxy server available for clients over Internet, please just refer to this article of Internet proxy server.
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When people talk about proxy servers, the first thing that comes to mind is a service that allows users to go online anonymously, but the truth is not all proxy servers provide this service, and it is not the main principle behind the concept. At the base level, a proxy service is a server that acts as a middle point between your pc and the Internet, making requests in place of your actual computer. Proxy servers are separated into two types, transparent and anonymous, based on how said request is made.

Below are the differnet proxy server types.

Transparent Proxies
A transparent proxy, as the name implies, is a proxy server that forwards your request to the destination without concealing or masking any of the information. This type of proxy is usually found in office networks, where there is no need to hide the IP address of a PC, since all the PCs in the network are safe. Transparent proxies are just used as central points of communication for all PCs in a network, and are not really the type of proxy that people have in mind when they shop for proxy server access online.

Anonymous Proxies
Anonymous Proxies hide the information that passes through it, usually used to hide the IP address of the PC that is using said server. This is very useful for secure communications, particularly with government agencies or large companies that don’t want their precious data to be stolen by malicious individuals. It can also be useful for normal users like us, as it protects us against hackers who snoop around for potential victims through IP addresses.

Highly Anonymous Proxies
There’s another type of anonymous proxy called Highly Anonymous Proxy. The main difference with this one is the fact that aside from hiding your IP, it also hides its presence so that the destination wouldn’t know that you are hiding behind a proxy. To them, you’re just accessing their server directly, and the IP that shows up will look like a personal IP Address instead of the obviously proxy IPs provided by anonymous proxies.

Socks 4 and Socks 5 Proxies
Socks 4 and Socks 5 are Internet protocols that are used for DNS lookup services and UDP Communication. Some proxy servers offer both protocols to their clients, since there is no actual cost difference between the two.

Which proxy server type should I use?
It really depends upon your needs and budget. Of course, if you want the highest security and function money can buy, you should go with high anonymous proxies. As there really isn’t any reason not to go with it, outside of price. If you don’t need to hide the fact that you are using a proxy, and just want to hide your IP address, then you’ll appreciate the much cheaper Anonymous proxy server.

Proxy Servers: Shared Vs Dedicated Proxies
When people are shopping for proxy services, one of the things that they find themselves thinking of is whether to go with a company that provides shared proxies or one that offers dedicated proxies. One can rest assured that a paid proxy is secure, so people don’t normally think about that part of the advertisement, the proxies being shared or dedicated, however, weighs in heavily during the decision making stage.

Between a shared and a dedicated proxy server, the deciding factor usually consists of budget and intended use, but if you want to know the specific differences, read on:

What is a Shared Proxy?
As the name implies, a shared proxy server is a proxy that is shared by many users. The main advantage of this is that the cost of maintaining the server can be spread out across many users, which means a shared proxy server costs a lot less, and the savings can be passed on to the subscribers by way of lower subscription fees and/or extra features. On the other hand, shared proxy servers have disadvantages that make up for the low costs:

1. The speeds of shared proxies are being shared by all the users, so you may end up getting slow speeds during peak hours, when many users are using the service at the same time.
2. All users of shared proxies are basically using IP Addresses from the same pool, and if there’s a user who abused the proxy, resulting in a ban from a website, you will end up being blacklisted from the site as well.

What is a Dedicated Proxy?
A dedicated proxy, as the name signifies, is a proxy server that is exclusive to the subscriber assigned to the account. The main advantage of a dedicated proxy is the fact that you have the entire service to yourself, which means fast speeds that will not change even during peak hours. You also get to use the service for whatever you like, without worrying about other subscribers abusing the proxy. A large number of dedicated proxies also give you the freedom to choose IP Addresses, as well as the location that will show up in your IP.

On the other hand, a Dedicated Proxy Server is very expensive compared to a shared one, because the service provider can’t spread out the upkeep cost over several users.

Shared or Dedicated?
At the end of the day, a shared and dedicated proxy will have its own strengths and weaknesses, but will server their own purposes as they both fit the needs of different people with different needs. Those who are short on budget have no choice but to be content with a shared proxy, but those with money to spare and a need for exclusive usage will want a dedicated proxy.

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In a computer network, a proxy server is any computer system offering a service that acts as an intermediary between the two communicating parties, the client and the server. In the presence of a proxy server, there is no direct communication between the client and the server. Instead, the client connects to the proxy server and sends requests for resources such as a document, web page or a file that resides on a remote server. The proxy server handles this request by fetching the required resources from the remote server and forwarding the same to the client.

How Proxy Server Works?
An illustration of how a proxy server works is shown below:

Working of a Proxy Server

As shown in the above example, whenever the client connects to a web proxy server and makes a request for the resources (in this case, “Sample.html”) that reside on a remote server (in this case, xyz.com), the proxy server forwards this request to the target server on behalf of the client, so as to fetch the requested resource and deliver it back to the client. An example of client can be a user operated computer that is connected to the Internet.

Types of Proxy Servers and their Uses:
1. Forward Proxies
A forward proxy is the same one described above where the proxy server forwards the client’s request to the target server to establish a communication between the two. Here the client specifies the resources to be fetched and the target server to connect to, so that the forward proxy server acts accordingly. Except for reverse proxy (discussed in the latter part of this article), all other types of proxy servers described in this article falls under forward proxy.

2. Open Proxy
An open proxy is a type of forwarding proxy that is openly available to any Internet user. Most often, an open proxy is used by Internet users to conceal their IP address so that they remain anonymous during their web activity. The following are some of the web proxies that fall under the category of open proxy:

Anonymous Proxy

An anonymous proxy is a type of open proxy that conceals IP address of Internet users so that the target server cannot identify the origin of the requesting client. However, an anonymous proxy identifies itself as a proxy server but still manages to maintain the anonymity of the users.

Distorting Proxy

This type of proxy server identifies itself as a proxy, but reveals an incorrect IP address of the client to the target server.

High Anonymity Proxy (Elite Proxy)

An elite proxy provides maximum anonymity as it neither identifies itself as a proxy nor reveals the original IP address of the client. In most cases, users have to pay for this type of proxy as it is seldom available freely on the Internet.

3. Reverse Proxy
Unlike a forwarding proxy where the client knows that it is connecting through a proxy, a reverse proxy appears to the client as an ordinary server. However, when the client requests resources from this server, it forwards those requests to the target server (actual server where the resources reside) so as to fetch back the requested resource and forward the same to the client. Here, the client is given an impression that it is connecting to the actual server, but in reality there exists a reverse proxy residing between the client and the actual server.

Reverse proxies are often used to reduce load on the actual server by load balancing, to enhance security and to cache static content, so that they can be served faster to the client. Often big companies like Google which gets a large number of hits maintain a reverse proxy so as to enhance the performance of their servers. It is not a surprise that whenever you are connecting to google.com, you are only connecting to a reverse proxy that forwards your search queries to the actual servers to return the results back to you.

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