Bogon filtering
Bogon filtering is the practice of blocking packets known as bogons, which are ones sent to a computer network claiming to originate from invalid or bogus IP addresses, known as bogon addresses.[1]
Etymology
[edit]The term bogon stems from hacker jargon, with the earliest appearance in the Jargon File in version 1.5.0 (dated 1983).[2] 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 hackish sense of being incorrect, absurd, and useless.[citation needed] 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.[3]
Types of bogon addresses
[edit]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[4][5], such as those in 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16 and fc00::/7,[5] loopback interfaces like 127.0.0.0/8 and ::1, and link-local addresses like 169.254.0.0/16 and fe80::/64 can be bogon addresses. Addresses for Carrier-grade NAT, Teredo, and 6to4 and documentation prefixes also fall into this category.[6] IP packets using these as source addresses are sometimes known as Martian packets.
Blocking and filtering
[edit]Many ISPs and end-user firewalls 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 access-control lists (ACLs), or by BGP blackholing.
Former bogon addresses
[edit]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 network operators' mailing lists (such as NANOG) to ensure that bogon filtering can be removed for addresses that have become legitimate. For example, addresses in 49.0.0.0/8 were not allocated prior to August 2010, but are now used by APNIC.[7]
As of November 2011[update], the Internet Engineering Task Force (IETF) recommends that, since there are no longer any unallocated IPv4 /8s, IPv4 bogon filters based on registration status should be removed.[8] However, bogon filters still need to check for Martian packets.
See also
[edit]- Reverse-path forwarding
- IP hijacking
- IP address spoofing
- Ingress filtering
- Internet background noise
References
[edit]- ^ "What is a bogon address?". APNIC. Retrieved 1 November 2024.
- ^ Guy L. Steele Jr.; Donald R. Woods; Raphael A. Finkel; Mark R. Crispin; Richard M. Stallman; Geoffrey S. Goodfellow (1983). "The Hacker's Dictionary: A Guide to the World of Computer Wizards". Jargon File Text Archive : A large collection of historical versions of the Jargon File. Archived from the original on November 8, 2020. Retrieved 28 May 2021.
- ^ "Ian McAnerin and Mike Churchill - 2005". McAnerin Networks Inc. Archived from the original on 2007-04-14. Retrieved 16 May 2020.
- ^ Y. Rekhter; B. Moskowitz; D. Karrenberg; G. J. de Groot; E. Lear (February 1996). Address Allocation for Private Internets. Network Working Group. doi:10.17487/RFC1918. BCP 5. RFC 1918. Best Current Practice 5. Obsoletes RFC 1627 and 1597. Updated by RFC 6761.
- ^ a b R. Hinden; B. Haberman (October 2005). Unique Local IPv6 Unicast Addresses. Network Working Group. doi:10.17487/RFC4193. RFC 4193. Proposed Standard.
- ^ "Bogon IP addresses". ipgeolocation. Retrieved 27 Jan 2022.
- ^ "IANA IPv4 Address Space Registry". IANA. 2010-02-22. Archived from the original on 2010-04-30. Retrieved 2010-03-18.
- ^ L. Vegoda (November 2011). Time to Remove Filters for Previously Unallocated IPv4 /8s. IETF. doi:10.17487/RFC6441. ISSN 2070-1721. BCP 171. RFC 6441. Best Common Practice.