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In computer networking, port knocking is a method of externally opening ports on a firewall by generating a connection attempt on a set of prespecified closed ports. Once a correct sequence of connection attempts is received, the firewall rules are dynamically modified to allow the host which sent the connection attempts to connect over specific port(s). A variant called single packet authorization (SPA) exists, where only a single "knock" is needed, consisting of an encrypted packet.[1][2][3][4]
The primary purpose of port knocking is to prevent an attacker from scanning a system for potentially exploitable services by doing a port scan, because unless the attacker sends the correct knock sequence, the protected ports will appear closed.
^Michael Rash (2004) Combining Port Knocking and Passive OS Fingerprinting with fwknop
^Michael Rash (2006). Single Packet Authorization with Fwknop.
^Michael Rash (2007). Protecting SSH Servers with Single Packet Authorization.
^Moxie Marlinspike (2009). Using knockknock for Single Packet Authorization.
networking, portknocking is a method of externally opening ports on a firewall by generating a connection attempt on a set of prespecified closed ports. Once...
Look up knocking in Wiktionary, the free dictionary. Knocking or Knockin or Knockin' may refer to: Knocking, Austria, a hamlet, subdivision of Erlauf...
periods. A similar case is portknocking. In usual communications the timing of requests is irrelevant and unwatched. Portknocking makes it significant. Handel...
country code top level domain (ccTLD) for Pakistan Portknocking, a method of externally opening ports on a firewall Public-key cryptography PK machine...
(TCP) to hide open ports of some TCP services from the public, in order to impede port scans. It is somewhat similar to the portknocking technique. As of...
Customs and Excise. The series derived its name from the distinctive "Knockknockknock" command used over the radio to synchronise a raid. Five series were...
(Xhosa: [ᶢǃʱɛ̀ɓéːxà]; English: /kɛˈbɛərxə/ keb-AIR-khə), previously named Port Elizabeth, and colloquially referred to as P.E., is a major seaport and the...
Port Adelaide Football Club is a professional Australian rules football club based in Alberton, South Australia. The club's senior men's team plays in...
limit of the Port of London Authority on its establishment in 1908). A line between North Foreland, Margate, Kent via the Kentish Knock lighthouse to...
Ship "JAHRE VIKING (370263)". Port State Information Exchange. United States Coast Guard. Retrieved 16 October 2012. "Knock Nevis (94118)". Shippingdatabase...
Port Shepstone is a large town situated on the mouth of the Mzimkhulu River, the largest river on the KwaZulu-Natal South Coast of South Africa. It is...
The Port Chicago disaster was a deadly munitions explosion of the ship SS E. A. Bryan on July 17, 1944, at the Port Chicago Naval Magazine in Port Chicago...
used by Gregg as a "living Oscar"; Tim accidentally resuscitates Mark by knocking him over. Delgado Media Holdings is sold back to Tim with the help of a...
of its single malt whisky are still available. When Port Ellen was closed in 1983, Diageo did knock down some of the buildings, repurposed others, and...
improve anti-knocking and engine performance, while also improving intake and fuel efficiency. Toyota adopted a siamese-type intake port, which reduces...
fourth highest-grossing arcade game of 1989 in Japan. The ZX Spectrum portknocked the long-standing RoboCop from the top of the UK sales charts in 1989...
Deuces Wild (2002), Don't Come Knocking (2005), Wild Tigers I Have Known (2006), Humboldt County (2008), and Bad Lieutenant: Port of Call New Orleans (2009)...
season, Melbourne's win over Hawthorn confirmed Collingwood, Brisbane Lions, Port Adelaide and Melbourne as the top 4, while Carlton sealed a finals appearance...
necessary reinforcements and supplies, and were to be used until major French ports could be captured and brought back into use after repair of the inevitable...
On 12 August 2015, a series of explosions at the Port of Tianjin in Tianjin, Northern China, killed 173 people, according to official reports, and injured...
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