Editing Bogon filtering

{{Short description|Discarding network packets with bogus addressing}}
'''Bogon filtering''' is the practice of blocking [[packet (information technology)|packets]] known as '''bogons''', which are ones sent to a [[computer network]] claiming to originate from invalid or bogus [[IP address]]es, known as '''bogon addresses'''.<ref>{{cite web |title=What is a bogon address? |url=https://www.apnic.net/manage-ip/apnic-services/registration-services/resource-quality-assurance/what-is-a-bogon-address/ |publisher=[[APNIC]] |access-date=1 November 2024 |language=en-AU}}</ref>

==Etymology==
The term ''bogon'' stems from [[Hacker (programmer subculture)|hacker]] [[jargon]], with the earliest appearance in the [[Jargon File]] in version 1.5.0 (dated 1983).<ref>{{cite web |author1=Guy L. Steele Jr. |author2=Donald R. Woods |author3=Raphael A. Finkel |author4=Mark R. Crispin |author5=Richard M. Stallman |author6=Geoffrey S. Goodfellow |title=The Hacker's Dictionary: A Guide to the World of Computer Wizards |url=http://jargon-file.org/archive/jargon-1.5.0.dos.txt |website=Jargon File Text Archive : A large collection of historical versions of the Jargon File |access-date=28 May 2021 |archive-url=https://web.archive.org/web/20201108161626/http://jargon-file.org/archive/jargon-1.5.0.dos.txt |archive-date=November 8, 2020 |language=English |date=1983}}</ref>  It is defined as the [[quantum]] of ''bogosity'', or the property of being bogus. A bogon packet is frequently bogus both in the conventional sense of being forged for illegitimate purposes, and in the [[Hacker (programmer subculture)|hackish]] sense of being incorrect, absurd, and useless.{{Citation needed|date=May 2021}} An alternative etymology suggests that 'bogon' derives from a portmanteau of "bogus logon", or a logon from a place you know no one can actually logon.<ref>{{cite web |title=Ian McAnerin and Mike Churchill - 2005 |url=http://www.mcanerin.com/EN/articles/bogon-01.asp |website=McAnerin Networks Inc. |archive-url=https://web.archive.org/web/20070414145327/http://www.mcanerin.com/EN/articles/bogon-01.asp |access-date=16 May 2020|archive-date=2007-04-14 }}</ref>

==Types of bogon addresses==
Areas of unallocated address space are called the '''bogon space'''. These are that are not in any range allocated the [[Internet Assigned Numbers Authority]] (IANA) or a [[regional Internet registry]] (RIR) for public internet use.

Bogon IPs also include some address ranges from allocated space. For example, addresses reserved for [[private networks]]{{Ref RFC|1918}}{{Ref RFC|4193}}, such as those in {{IPaddr|10.0.0.0|8}}, {{IPaddr|172.16.0.0|12}}, {{IPaddr|192.168.0.0|16}} and {{IPaddr|fc00::/7}},{{Ref RFC|4193}} [[loopback|loopback interfaces]] like {{IPaddr|127.0.0.0|8}} and {{IPaddr|::1}}, and [[link-local address|link-local addresses]] like {{IPaddr|169.254.0.0|16}} and {{IPaddr|fe80::/64}} can be bogon addresses. Addresses for [[Carrier-grade NAT]], [[Teredo tunneling|Teredo]], and [[6to4]] and documentation prefixes also fall into this category.<ref>{{Cite web|title=Bogon IP addresses|publisher=ipgeolocation|url=https://ipgeolocation.io/resources/bogon.html|access-date=27 Jan 2022}}</ref> IP packets using these as source addresses are sometimes known as [[Martian packet]]s.

==Blocking and filtering==
Many [[Internet service provider|ISP]]s and end-user [[Firewall (networking)|firewall]]s filter and block bogons, because they have no legitimate use, and usually are the result of accidental misconfiguration or malicious intent. Bogons can be filtered by using [[router (computing)|router]] [[access-control list]]s (ACLs), or by [[BGP]] [[Black hole (networking)|blackholing]].

==Former bogon addresses==
IP addresses in the bogon space may cease to be bogons because IANA frequently assigns new address. Announcements of new assignments are often published on [[Computer network|network]] operators' [[mailing list]]s (such as [[NANOG (computing)|NANOG]]) to ensure that bogon filtering can be removed for addresses that have become legitimate. For example, addresses in {{IPaddr|49.0.0.0|8}} were not allocated prior to August 2010, but are now used by [[APNIC]].<ref name=address>{{cite web |url=https://www.iana.org/assignments/ipv4-address-space/ |title=IANA IPv4 Address Space Registry |access-date=2010-03-18 |date=2010-02-22 |publisher=[[Internet Assigned Numbers Authority|IANA]] |archive-url=https://web.archive.org/web/20100430190605/https://www.iana.org/assignments/ipv4-address-space/ |archive-date=2010-04-30 |url-status=live }}</ref> 

{{As of|2011|11}}, the [[Internet Engineering Task Force]] (IETF) recommends that, [[IPv4 address exhaustion|since there are no longer any unallocated IPv4 {{IPaddr||8}}s]], IPv4 bogon filters based on registration status should be removed.{{Ref RFC|6441}}
However, bogon filters still need to check for Martian packets.

==See also==
* [[Reverse-path forwarding]]
* [[IP hijacking]]
* [[IP address spoofing]]
* [[Ingress filtering]]
* [[Internet background noise]]

==References==
{{Reflist}}

==External links==
* [https://web.archive.org/web/20070414145327/http://www.mcanerin.com/EN/articles/bogon-01.asp Bogons Ate My Website]
* [http://www.toonk.nl/bogons.php Bogon traffic analysis report, netflow and spam analysis ] {{Webarchive|url=https://web.archive.org/web/20150316073337/http://www.toonk.nl/bogons.php |date=2015-03-16 }}
* [https://www.ripe.net/publications/docs/ripe-351 RIPE NCC: De-Bogonising New Address Blocks]
* [https://www.team-cymru.com/bogon-reference.html Team Cymru Bogon Reference]

[[Category:Computer jargon]]
[[Category:Internet Protocol]]