38-406: In computer networking , a proxy server is a server application that acts as an intermediary between a client requesting a resource and the server providing that resource. It improves privacy, security, and possibly performance in the process. Instead of connecting directly to a server that can fulfill a request for a resource, such as a file or web page , the client directs the request to
76-426: A caching proxy. Caching proxies were the first kind of proxy server. Web proxies are commonly used to cache web pages from a web server. Poorly implemented caching proxies can cause problems, such as an inability to use user authentication. A proxy that is designed to mitigate specific link related issues or degradation is a Performance Enhancing Proxy (PEPs). These are typically used to improve TCP performance in
114-465: A client, forwards that request to another one of many other servers, and then returns the results from the server that specifically processed the request to the client. Effectively a reverse proxy acts as a gateway between clients, users and application servers and handles all the traffic routing whilst also protecting the identity of the server that physically processes the request. A content-filtering web proxy server provides administrative control over
152-526: A combination of machine and human translation. Different translation proxy implementations have different capabilities. Some allow further customization of the source site for the local audiences such as excluding the source content or substituting the source content with the original local content. An anonymous proxy server (sometimes called a web proxy) generally attempts to anonymize web surfing. Anonymizers may be differentiated into several varieties. The destination server (the server that ultimately satisfies
190-484: 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. Some anonymizing proxy servers may forward data packets with header lines such as HTTP_VIA, HTTP_X_FORWARDED_FOR, or HTTP_FORWARDED, which may reveal the IP address of the client. Other anonymizing proxy servers, known as elite or high-anonymity proxies, make it appear that
228-453: A non-blacklisted location. Proxies can be installed in order to eavesdrop upon the data-flow between client machines and the web. All content sent or accessed – including passwords submitted and cookies used – can be captured and analyzed by the proxy operator. For this reason, passwords to online services (such as webmail and banking) should always be exchanged over a cryptographically secured connection, such as SSL. By chaining
266-515: A security flaw in the way that transparent proxies operate was published by Robert Auger, 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 policies and to ease administrative overheads since no client browser configuration is required. This second reason, however
304-721: A shared cache. In integrated firewall/proxy servers where the router/firewall is on the same host as the proxy, communicating original destination information can be done by any method, for example Microsoft TMG or WinGate . Computer networking Too Many Requests If you report this error to the Wikimedia System Administrators, please include the details below. Request from 172.68.168.150 via cp1114 cp1114, Varnish XID 933300978 Upstream caches: cp1114 int Error: 429, Too Many Requests at Thu, 28 Nov 2024 08:31:22 GMT Daemon (computer software) Too Many Requests If you report this error to
342-461: A website experience for different markets. Traffic from the global audience 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. The original language content in the response is replaced by the translated content as it passes back through the proxy. The translations used in a translation proxy can be either machine translation, human translation, or
380-444: A workplace setting where the client is managed by the organization, devices may be configured to trust a root certificate whose private key is known to the proxy. In such situations, proxy analysis of the contents of an SSL/TLS transaction becomes possible. The proxy is effectively operating a man-in-the-middle attack , allowed by the client's trust of a root certificate the proxy owns. If the destination server filters content based on
418-518: Is a certain type. Manual labor is used to correct the resultant database based on complaints or known flaws in the content-matching algorithms. Some proxies scan outbound content, e.g., for data loss prevention; or scan content for malicious software. Web filtering proxies are not able to peer inside secure sockets HTTP transactions, assuming the chain-of-trust of SSL/TLS ( Transport Layer Security ) has not been tampered with. The SSL/TLS chain-of-trust relies on trusted root certificate authorities . In
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#1732782682311456-429: Is a proxy that modifies the request or response in order to provide some added service to the user agent, such as group annotation services, media type transformation, protocol reduction, or anonymity filtering". TCP Intercept is a traffic filtering security feature that protects TCP servers from TCP SYN flood attacks, which are a type of denial-of-service attack. TCP Intercept is available for IP traffic only. In 2009
494-411: Is acceptable. At this point, a dynamic filter may be applied on the return path. For example, JPEG files could be blocked based on fleshtone matches, or language filters could dynamically detect unwanted language. If the content is rejected then an HTTP fetch error may be returned to the requester. Most web filtering companies use an internet-wide crawling robot that assesses the likelihood that content
532-406: Is done either with a specialized proxy, called a content filter (both commercial and free products are available), or by using a cache-extension protocol such as ICAP, that allows plug-in extensions to an open caching architecture. Websites commonly used by students to circumvent filters and access blocked content often include a proxy, from which the user can then access the websites that the filter
570-409: Is in most occasions external to the network. This means it can regulate traffic according to preset policies, convert and mask client IP addresses, enforce security protocols and block unknown traffic. A forward proxy enhances security and policy enforcement within an internal network. A reverse proxy, instead of protecting the client, is used to protect the servers. A reverse proxy accepts a request from
608-442: 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.g. island nations) or must be paid for. The diversion or interception of a TCP connection creates several issues. First,
646-724: Is more of an inconvenience than a risk, proxy users may find themselves being blocked from certain Web sites, as numerous forums and Web sites block IP addresses from proxies known to have spammed or trolled the site. Proxy bouncing can be used to maintain privacy. A caching proxy server accelerates service requests by retrieving the content saved from a previous request made by the same client or even other clients. Caching proxies keep local copies of frequently requested resources, allowing large organizations to significantly reduce their upstream bandwidth usage and costs, while significantly increasing performance. Most ISPs and large businesses have
684-564: 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, and then the user connects to a site that also requires authentication. Finally, intercepting connections can cause problems for HTTP caches, as some requests and responses become uncacheable by
722-399: Is trying to block. Requests may be filtered by several methods, such as a URL or DNS blacklists , URL regex filtering, MIME filtering, or content keyword filtering. Blacklists are often provided and maintained by web-filtering companies, often grouped into categories (pornography, gambling, shopping, social networks, etc..). The proxy then fetches the content, assuming the requested URL
760-487: The Internet and with a destination of one of the neighborhood's web servers goes through the proxy server. The use of "reverse" originates in its counterpart "forward proxy" since the reverse proxy sits closer to the web server and serves only a restricted set of websites. There are several reasons for installing reverse proxy servers: A forward proxy is a server that routes traffic between clients and another system, which
798-534: The Internet). A reverse proxy is usually an internal-facing proxy used as a front-end to control and protect access to a server on a private network. A reverse proxy commonly also performs tasks such as load-balancing , authentication , decryption , and caching . An open proxy is a forwarding proxy server that is accessible by any Internet user. In 2008, network security expert Gordon Lyon estimated that "hundreds of thousands" of open proxies are operated on
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#1732782682311836-460: The Internet. A reverse proxy (or surrogate) is a proxy server that appears to clients to be an ordinary server. Reverse proxies forward requests to one or more ordinary servers that handle the request. The response from the original server is returned as if it came directly from the proxy server, leaving the client with no knowledge of the original server. Reverse proxies are installed in the vicinity of one or more web servers. All traffic coming from
874-519: The URLs accessed by specific users or to monitor bandwidth usage statistics. It may also communicate to daemon -based or ICAP -based antivirus software to provide security against viruses and other malware by scanning incoming content in real-time before it enters the network. Many workplaces, schools, and colleges restrict web sites and online services that are accessible and available in their buildings. Governments also censor undesirable content. This
912-450: 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. Secondary market brokers use web proxy servers to circumvent restrictions on online purchases of limited products such as limited sneakers or tickets. Web proxies forward HTTP requests. The request from
950-757: The client is the same as a regular HTTP request except the full URL is passed, instead of just the path. This request is sent to the proxy server, the proxy makes the request specified and returns the response. Some web proxies allow the HTTP CONNECT method to set up forwarding of arbitrary data through the connection; a common policy is to only forward port 443 to allow HTTPS traffic. Examples of web proxy servers include Apache (with mod_proxy or Traffic Server ), HAProxy , IIS configured as proxy (e.g., with Application Request Routing), Nginx , Privoxy , Squid , Varnish (reverse proxy only), WinGate , Ziproxy , Tinyproxy, RabbIT and Polipo . For clients,
988-409: The content that may be relayed in one or both directions through the proxy. It is commonly used in both commercial and non-commercial organizations (especially schools) to ensure that Internet usage conforms to acceptable use policy . Content filtering proxy servers will often support user authentication to control web access. It also usually produces logs , either to give detailed information about
1026-447: 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 . RFC 2616 (Hypertext Transfer Protocol—HTTP/1.1) offers standard definitions: "A 'transparent proxy' is a proxy that does not modify the request or response beyond what is required for proxy authentication and identification". "A 'non-transparent proxy'
1064-410: The local network anonymous. 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.g. images, music files, etc.) when cross-domain restrictions prohibit the web site from linking directly to the outside domains. Proxies also allow
1102-660: The origin of the request, the use of a proxy can circumvent this filter. 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. Web proxies are the most common means of bypassing government censorship, although no more than 3% of Internet users use any circumvention tools. Some proxy service providers allow businesses access to their proxy network for rerouting traffic for business intelligence purposes. In some cases, users can circumvent proxies that filter using blacklists by using services designed to proxy information from
1140-477: The original destination IP and port must somehow be communicated to the proxy. This is not always possible (e.g., where the gateway and proxy reside on different hosts). There is a class of cross-site attacks that depend on certain behaviors 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
1178-402: 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. PEPs can make more efficient use of the network, for example, by merging TCP ACKs (acknowledgements) or compressing data sent at the application layer . A translation proxy is a proxy server that is used to localize
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1216-461: The problem of complex or multiple proxy-servers is solved by a client-server Proxy auto-config protocol ( PAC file ). SOCKS also forwards arbitrary data after a connection phase, and is similar to HTTP CONNECT in web proxies. Also known as an intercepting proxy , inline proxy , or forced proxy , a transparent proxy intercepts normal application layer communication without requiring any special client configuration. Clients need not be aware of
1254-459: The proxies which do not reveal data about the original requester, it is possible to obfuscate activities from the eyes of the user's destination. However, more traces will be left on the intermediate hops, which could be used or offered up to trace the user's activities. If the policies and administrators of these other proxies are unknown, the user may fall victim to a false sense of security just because those details are out of sight and mind. In what
1292-406: The proxy server is the client. A website could still suspect a proxy is being used if the client sends packets that 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
1330-433: The proxy server, which evaluates the request and performs the required network transactions. This serves as a method to simplify or control the complexity of the request, or provide additional benefits such as load balancing , privacy, or security. Proxies were devised to add structure and encapsulation to distributed systems . A proxy server thus functions on behalf of the client when requesting service, potentially masking
1368-457: The request source IP address and uses a geo-IP database to determine the geographic source of requests. Using a proxy server that is physically located inside a specific country or a city gives advertisers the ability to test geotargeted ads. 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. This makes requests from machines and users on
1406-504: The true origin of the request to the resource server. A proxy server may reside on the user's local computer , or at any point between the user's computer and destination servers on the Internet . A proxy server that passes unmodified requests and responses is usually called a gateway or sometimes a tunneling proxy . A forward proxy is an Internet-facing proxy used to retrieve data from a wide range of sources (in most cases, anywhere on
1444-413: 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. Access control : Some proxy servers implement
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