HTTP proxy server: what is it?

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Proxy server
Let's have a more detailed look over its abilities. For example Flash or Java applets are a perfect example how a proxy connection can get broken, Flash and Java both might not care much about the proxy settings of their parent application browser. Related Terms cache computing A cache -- pronounced CASH -- is hardware or software that is used to store something, usually data, temporarily in a computing A website could still suspect a proxy is being used if the client sends packets which include a cookie from a previous visit that did not use the high-anonymity proxy server. In a workplace setting where the client is managed by the organization, trust might be granted to a root certificate whose private key is known to the proxy.

Proxy Server

What is the difference between a SOCKS proxy and an HTTP proxy?

These typically are used to improve TCP performance in the presence of high round-trip times or high packet loss such as wireless or mobile phone networks ; or highly asymmetric links featuring very different upload and download rates.

Another important use of the proxy server is to reduce the hardware cost. An organization may have many systems on the same network or under control of a single server, prohibiting the possibility of an individual connection to the Internet for each system. In such a case, the individual systems can be connected to one proxy server, and the proxy server connected to the main server. A translation proxy is a proxy server that is used to localize a website experience for different markets.

Traffic from global audiences is routed through the translation proxy to the source website. As visitors browse the proxied site, requests go back to the source site where pages are rendered. Original language content in the response is replaced by translated content as it passes back through the proxy. The translations used in a translation proxy can be either machine translation, human translation, or a combination of machine and human translation.

Different translation proxy implementations have different capabilities. Some allow further customization of the source site for local audiences such as excluding source content or substituting source content with original local content.

An anonymous proxy server sometimes called a web proxy generally attempts to anonymize web surfing. There are different varieties of anonymizers.

The destination server the server that ultimately satisfies the web request receives requests from the anonymizing proxy server, and thus does not receive information about the end user's address. The requests are not anonymous to the anonymizing proxy server, however, and so a degree of trust is present between the proxy server and the user.

Many proxy servers are funded through a continued advertising link to the user. Some proxy servers implement a logon requirement. In large organizations, authorized users must log on to gain access to the web.

The organization can thereby track usage to individuals. Other anonymizing proxy servers, known as elite or high-anonymity proxies, make it appear that the proxy server is the client. A website could still suspect a proxy is being used if the client sends packets which include a cookie from a previous visit that did not use the high-anonymity proxy server.

Clearing cookies, and possibly the cache, would solve this problem. Advertisers use proxy servers for validating, checking and quality assurance of geotargeted ads. A geotargeting ad server checks the request source IP address and uses a geo-IP database to determine the geographic source of requests. A proxy can keep the internal network structure of a company secret by using network address translation , which can help the security of the internal network.

Proxies can also be combined with firewalls. An incorrectly configured proxy can provide access to a network otherwise isolated from the Internet. Proxies allow web sites to make web requests to externally hosted resources e.

Proxies also allow the browser to make web requests to externally hosted content on behalf of a website when cross-domain restrictions in place to protect websites from the likes of data theft prohibit the browser from directly accessing the outside domains. Not to be confused with secondary market , secondary market brokers use web proxy servers to buy large stocks of limited products such as limited sneakers [12] or tickets.

Web proxies forward HTTP requests. This request is sent to the proxy server, the proxy makes the request specified and returns the response. Also known as an intercepting proxy , inline proxy , or forced proxy , a transparent proxy intercepts normal communication at the network layer without requiring any special client configuration.

Clients need not be aware of the existence of the proxy. A transparent proxy is normally located between the client and the Internet, with the proxy performing some of the functions of a gateway or router.

In a security flaw in the way that transparent proxies operate was published by Robert Auger, [15] and the Computer Emergency Response Team issued an advisory listing dozens of affected transparent and intercepting proxy servers. Intercepting proxies are commonly used in businesses to enforce acceptable use policy, and to ease administrative overheads, since no client browser configuration is required. This second reason however is mitigated by features such as Active Directory group policy, or DHCP and automatic proxy detection.

Intercepting proxies are also commonly used by ISPs in some countries to save upstream bandwidth and improve customer response times by caching. This is more common in countries where bandwidth is more limited e. Firstly the original destination IP and port must somehow be communicated to the proxy. This is not always possible e. There is a class of cross site attacks that depend on certain behaviour of intercepting proxies that do not check or have access to information about the original intercepted destination.

This problem may be resolved by using an integrated packet-level and application level appliance or software which is then able to communicate this information between the packet handler and the proxy. Intercepting also creates problems for HTTP authentication, especially connection-oriented authentication such as NTLM , as the client browser believes it is talking to a server rather than a proxy. This can cause problems where an intercepting proxy requires authentication, then the user connects to a site which also requires authentication.

Finally intercepting connections can cause problems for HTTP caches, as some requests and responses become uncacheable by a shared cache. This proprietary protocol resides on the router and is configured from the cache, allowing the cache to determine what ports and traffic is sent to it via transparent redirection from the router.

This redirection can occur in one of two ways: Once traffic reaches the proxy machine itself interception is commonly performed with NAT Network Address Translation.

Such setups are invisible to the client browser, but leave the proxy visible to the web server and other devices on the internet side of the proxy. There are several methods that can often be used to detect the presence of an intercepting proxy server:.

A CGI web proxy accepts target URLs using a Web form in the user's browser window, processes the request, and returns the results to the user's browser. Consequently, it can be used on a device or network that does not allow "true" proxy settings to be changed.

As of April , Glype has received almost a million downloads, [20] whilst PHProxy still receives hundreds of downloads per week. Some CGI proxies were set up for purposes such as making websites more accessible to disabled people, but have since been shut down due to excessive traffic , usually caused by a third party advertising the service as a means to bypass local filtering. Since many of these users don't care about the collateral damage they are causing, it became necessary for organizations to hide their proxies, disclosing the URLs only to those who take the trouble to contact the organization and demonstrate a genuine need.

A suffix proxy allows a user to access web content by appending the name of the proxy server to the URL of the requested content e. Suffix proxy servers are easier to use than regular proxy servers but they do not offer high levels of anonymity and their primary use is for bypassing web filters.

However, this is rarely used due to more advanced web filters. Tor short for The Onion Router is a system intended to enable online anonymity. Using Tor makes it more difficult to trace Internet activity, including "visits to Web sites, online posts, instant messages and other communication forms", back to the user.

The original data are encrypted and re-encrypted multiple times, then sent through successive Tor relays, each one of which decrypts a "layer" of encryption before passing the data on to the next relay and ultimately the destination. This reduces the possibility of the original data being unscrambled or understood in transit. The Tor client is free software , and there are no additional charges to use the network.

The I2P anonymous network 'I2P' is a proxy network aiming at online anonymity. It implements garlic routing , which is an enhancement of Tor 's onion routing. I2P is fully distributed and works by encrypting all communications in various layers and relaying them through a network of routers run by volunteers in various locations. By keeping the source of the information hidden, I2P offers censorship resistance.

The goals of I2P are to protect users' personal freedom, privacy, and ability to conduct confidential business. Each user of I2P runs an I2P router on their computer node. The I2P router takes care of finding other peers and building anonymizing tunnels through them. The software is free and open-source , and the network is free of charge to use. Most of the time 'proxy' refers to a layer-7 application on the OSI reference model. The difference between these two proxy technologies is the layer in which they operate, and the procedure to configuring the proxy clients and proxy servers.

In client configuration of layer-3 proxy NAT , configuring the gateway is sufficient. However, for client configuration of a layer-7 proxy, the destination of the packets that the client generates must always be the proxy server layer-7 , then the proxy server reads each packet and finds out the true destination.

Because NAT operates at layer-3, it is less resource-intensive than the layer-7 proxy, but also less flexible.

As we compare these two technologies, we might encounter a terminology known as 'transparent firewall'. A proxy server is a dedicated computer or a software system running on a computer that acts as an intermediary between an endpoint device, such as a computer, and another server from which a user or client is requesting a service.

The proxy server may exist in the same machine as a firewall server or it may be on a separate server, which forwards requests through the firewall. An advantage of a proxy server is that its cache can serve all users. If one or more Internet sites are frequently requested, these are likely to be in the proxy's cache, which will improve user response time. A proxy can also log its interactions, which can be helpful for troubleshooting. When a proxy server receives a request for an Internet resource such as a Web page , it looks in its local cache of previously pages.

If it finds the page, it returns it to the user without needing to forward the request to the Internet. If the page is not in the cache, the proxy server, acting as a client on behalf of the user, uses one of its own IP addresses to request the page from the server out on the Internet. When the page is returned, the proxy server relates it to the original request and forwards it on to the user.

Proxy servers are used for both legal and illegal purposes. In the enterprise, a proxy server is used to facilitate security, administrative control or caching services, among other purposes. In a personal computing context, proxy servers are used to enable user privacy and anonymous surfing. Proxy servers can also be used for the opposite purpose: To monitor traffic and undermine user privacy. To the user, the proxy server is invisible; all Internet requests and returned responses appear to be directly with the addressed Internet server.

The proxy is not actually invisible; its IP address has to be specified as a configuration option to the browser or other protocol program. Users can access web proxies online or configure web browsers to constantly use a proxy server. Proxy servers may serve many users or just one per server. These options are called shared and dedicated proxies, respectively.

There are a number of reasons for proxies and thus a number of types of proxy servers, often in overlapping categories. Forward and reverse proxy servers Forward proxies send the requests of a client onward to a web server. Users access forward proxies by directly surfing to a web proxy address or by configuring their Internet settings.

Forward proxies allow circumvention of firewalls and increase the privacy and security for a user but may sometimes be used to download illegal materials such as copyrighted materials or child pornography. Reverse proxies transparently handle all requests for resources on destination servers without requiring any action on the part of the requester. Sites might be blocked for more or less legitimate reasons. Reverse proxies may be used to prevent access to immoral, illegal or copyrighted content.

Sometimes these reasons are justifiable but sometimes justification is dubious. Reverse proxies sometimes prevent access news sites where users could view leaked information. They can also prevent users from accessing sites where they can disclose information about government or industry actions.

Blocking access to such websites may violate free speech rights. More types of proxies Transparent proxies are typically found near the exit of a corporate network. These proxies centralize network traffic. On corporate networks, a proxy server is associated with -- or is part of -- a gateway server that separates the network from external networks typically the Internet and a firewall that protects the network from outside intrusion and allows data to be scanned for security purposes before delivery to a client on the network.

These proxies help with monitoring and administering network traffic as the computers in a corporate network are usually safe devices that do not need anonymity for typically mundane tasks. Anonymous proxies hide the IP address of the client using them allow to access materials that are blocked by firewalls or to circumvent IP address bans.

Highly anonymous proxies hide even the fact that they are being used by clients and present a non-proxy public IP address. So not only do they hide the IP address of the client using them, they also allow access to sites that might block proxy servers.

Some proxy servers offer both Socks protocols. Proxy hacking In proxy hacking , an attacker attempts to steal hits from an authentic web page in a search engine's index and search results pages.

The proxy hacker would have a either a fraudulent site emulating the original or whatever they felt like showing the clients requesting the page. Here's how it works: The attacker creates a copy of the targeted web page on a proxy server and uses methods such as keyword stuffing and linking to the copied page from external sites to artificially raise its search engine ranking.

The authentic page will rank lower and may be seen as duplicated content, in which case a search engine may remove it from its index.

Why Use a Proxy?

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Sep 07,  · 1) HTTP Proxy is basically a webaddress you type in to your companies proxy server so you can access the internet. 2) Off, the option is off and manual you type in the address to the proxy and the port number and automatic you point it to a file on the proxy server that automatically sets the the proxy settings for you. An HTTP Proxy serves two intermediary roles as an HTTP Client and an HTTP Server for security, management, and caching functionality. The HTTP Proxy routes HTTP Client requests from a Web browser to the Internet, while supporting the caching of . Proxy server. In computer networks, a proxy server is a server (a computer system or an application) that acts as an intermediary for requests from .