Editing Martian packet (section)

{{Short description|IP packet on the public internet}}
A '''Martian packet''' is an [[Internet Protocol|IP]] [[Packet (information technology)|packet]] seen on the [[public Internet]] that contains a source or destination address that is [[Reserved IP addresses|reserved for special use]] by the [[Internet Assigned Numbers Authority]] (IANA) as defined in {{IETF RFC|1812}}, Appendix B Glossary (Martian Address Filtering). On the public Internet, such a packet either has a [[IP address spoofing|spoofed]] source address, and it cannot actually originate as claimed, or the packet cannot be delivered.<ref name=":0">{{Cite ietf |rfc=1812 |title=Requirements for IP Version 4 Routers |last=Baker |date=June 1995 |first=F. |access-date=2021-08-18}}</ref> The requirement to filter these packets (i.e. not forward them) is found in {{IETF RFC|1812}}, Section 5.3.7 (Martian Address Filtering).

Martian packets commonly arise from [[IP address spoofing]] in [[denial-of-service attack]]s,<ref name=RFC3704>{{cite ietf |rfc=3704 |title=Ingress Filtering for Multihomed Networks |first1=F. |last1=Baker |first2=P. |last2=Savola |bcp=84 |date=March 2004 |access-date=2021-08-18}}</ref> but can also arise from network equipment malfunction or misconfiguration of a [[Host (network)|host]].<ref name=":0" />

In [[Linux]] terminology, a Martian packet is an IP packet received by the kernel on a specific interface, while routing tables indicate that the source IP is expected on another interface.<ref>{{cite web |url=https://www.suse.com/support/kb/doc/?id=000016540 |title=Martian sources errors showing in messages log |access-date=2022-07-02}}</ref><ref>{{cite web |url=https://support.hpe.com/hpesc/public/docDisplay?docId=c02191085&docLocale=en_US |title=Red Hat Enterprise Linux 5.2 - Kernel: Martian Source Messages |access-date=2022-07-02}}</ref>

The name is derived from ''packet from Mars'', meaning that packet seems to be not of this Earth.<ref>{{cite web |url=http://www.catb.org/jargon/html/M/martian.html |title=Jargon File: martian |access-date=2010-12-25 |archive-date=2010-12-17 |archive-url=https://web.archive.org/web/20101217025706/http://catb.org/jargon/html/M/martian.html |url-status=live }}</ref>