Editing Open proxy

{{short description|Proxy server accessible to any Internet user}}
{{For|Wikipedia's policy on editing from open proxies|Wikipedia:Open proxies|selfref=yes}}
[[File:Open proxy h2g2bob.svg|thumb|200x200px|alt=Diagram of proxy server connected to the Internet|An open proxy forwarding requests from and to anywhere on the Internet]]
An '''open proxy''' is a type of [[proxy server]] that is accessible by any [[Internet]] user.

Generally, a proxy server only allows users within a network group (i.e. a '''closed proxy''') to [[store and forward]] Internet services such as [[Domain Name System|DNS]] or [[web page]]s to reduce and control the [[bandwidth (computing)|bandwidth]] used by the group. With an open proxy, however, any user on the Internet can use this forwarding service.

==Advantages==
An anonymous open proxy is useful to those looking for online anonymity and privacy, as it can help users hide their [[IP address]] from web servers since the server requests appear to originate from the proxy server. It makes it harder to reveal their identity and thereby helps preserve their perceived security while browsing [[World Wide Web|the web]] or using other [[internet service]]s. Real anonymity and extensive [[internet security]] might not be achieved by this measure alone as website operators can use [[Client (computing)|client-side]] scripts to determine the browser's real IP address and the open proxy may be keeping logs of all connections. Open proxies also do not stop [[tracking cookies]] and [[device fingerprinting|fingerprinters]] from identifying users.<ref name="HTGMyths">{{cite web |last1=O'sullivan |first1=Fergus |title=VPN Myths Debunked: What VPNs Can and Cannot Do |url=https://www.howtogeek.com/753661/vpn-myths-debunked-what-vpns-can-and-cannot-do/ |website=How-To Geek |date=27 September 2021 |access-date=16 January 2022}}</ref>

Most public [[VPN]]s work through open proxies.

==Disadvantages==
It is possible for a computer to run as an open proxy server without the computer's owner knowing it. This can result from misconfiguration of proxy software running on the computer, or from infection with [[malware]] ([[computer virus|viruses]], [[trojan horse (computing)|trojans]] or [[computer worm|worms]]) designed for this purpose.<ref>{{cite web|url = http://www.acma.gov.au/Industry/Internet/e-Security/Australian-Internet-Security-Initiative/accidental-spamming-and-zombies-esecurity-i-acma|title = Accidental spamming, zombies and spoofing|access-date = 2015-12-08|publisher = [[Australian Communications and Media Authority]]|archive-url = https://web.archive.org/web/20151225043140/http://www.acma.gov.au/Industry/Internet/e-Security/Australian-Internet-Security-Initiative/accidental-spamming-and-zombies-esecurity-i-acma|archive-date = 2015-12-25|url-status = dead}}</ref> If it is caused by malware, the infected computer is known as a [[zombie computer]].

==Testing for access from an open proxy==
Because open proxies are often implicated in abuse, a number of methods have been developed to detect them and to refuse service to them. [[IRC]] networks with strict usage policies automatically test client systems for known types of open proxies.<ref>{{cite web |url= http://www.bestvpnservicemag.com/blitzed-open-proxy-monitor-bopm-version-2-3/ |title= Blitzed Open Proxy Monitor |publisher= Blitzed.org |date= 2011-08-21 |access-date= June 21, 2014 |url-status= dead |archive-url= https://web.archive.org/web/20140815234109/http://www.bestvpnservicemag.com/blitzed-open-proxy-monitor-bopm-version-2-3/ |archive-date= August 15, 2014 }}</ref> Likewise, a [[mail transport agent|mail server]] may be configured to automatically test mail senders for open proxies, using [[software]] such as proxycheck.<ref>{{cite web|url= http://www.corpit.ru/mjt/proxycheck.html |title= proxycheck: Open Proxy checker |publisher= Corpit.ru |access-date= 2011-11-21 }}</ref>

Groups of IRC and electronic mail operators run [[DNSBL]]s publishing lists of the [[IP address]]es of known open proxies, such as [[AHBL]], [[Composite Blocking List|CBL]], [[NJABL]] (till 2013), and [[SORBS]] (in operation since 2002). The AHBL discontinued public access in 2015.<ref>{{cite web|url=https://www.ahbl.org/|title=Official Abusive Hosts Blocking List Website}}</ref>

==See also==
* [[Anonymizing proxy]]
* [[Open mail relay]]

==References==
{{Reflist}}

[[Category:Internet security]]
[[Category:Proxy servers]]

[[es:Proxy#Proxy Abierto]]
[[pt:Proxy#Proxy abreto]]