What is DNS hijacking?
The [[Domain Name System]] is a way to map a [[domain name]] to an [[IP address]]. '''DNS hijacking''', '''DNS poisoning''', and '''DNS redirection''' are names for changing this mapping. Usually, this is done by pointing to a different [[name server]].<ref>{{Cite web|title=What is a DNS Hijacking {{!}} Redirection Attacks Explained {{!}} Imperva|url=https://www.imperva.com/learn/application-security/dns-hijacking-redirection/|access-date=2020-12-13|website=Learning Center|language=en-US|archive-date=2022-04-12|archive-url=https://web.archive.org/web/20220412141626/https://www.imperva.com/learn/application-security/dns-hijacking-redirection/|url-status=live}}</ref> This name server will then return a different IP address for the domain. [[Hacker|Hackers]] use this, for example for [[phishing]], or to show [[Advertisment|advertisments]]. The [[government]] also uses it sometimes: accessing certain domains may be [[illegal]], in certain [[countries]]. Using this technique, the government can require [[Internet service provider|internet service providers]] to block such domains. If the government says that certain domains must no longer be accessible, this is a form of [[censorship]]. == How it works == When the DNS server has no entry for a domain, it will return an NXDOMAIN respone. The government could therefore require ISPs to return NXDOMAIN responses for the domains that are forbidden. The DNS server operated by the ISP or by hackers could send the user to a page where [[Advertising|adverts]] are shown, were statistics can be collected, or other things can be done. There's also a different problem: Most web applications rely on the fact that they get an NXDOMAIN response for domains that do not exist. If they now get a valid page (for example with advertisments), this breaks the appliction. == What can be done against it == One way to overcome this problem is to use [[Domain Name System Security Extensions]], often shorened to DNSSec. DNSSec is an extennsion of DN which uses [[asymmetric cryptogr