Template:Short description A Martian packet is an IP packet seen on the public Internet that contains a source or destination address that is reserved for special use by the Internet Assigned Numbers Authority (IANA) as defined in Template:IETF RFC, Appendix B Glossary (Martian Address Filtering). On the public Internet, such a packet either has a spoofed source address, and it cannot actually originate as claimed, or the packet cannot be delivered.<ref name=":0">Template:Cite ietf</ref> The requirement to filter these packets (i.e. not forward them) is found in Template:IETF RFC, Section 5.3.7 (Martian Address Filtering).
Martian packets commonly arise from IP address spoofing in denial-of-service attacks,<ref name=RFC3704>Template:Cite ietf</ref> but can also arise from network equipment malfunction or misconfiguration of a 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>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
The name is derived from packet from Mars, meaning that packet seems to be not of this Earth.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
IPv4 and IPv6Edit
In both IPv4 and IPv6, a Martian packet has a source address, a destination address, or both within one of the special-use ranges.<ref name=rfc6890>Template:Cite IETF Updated by Template:IETF RFC.</ref>
Transition mechanismsEdit
6to4Edit
6to4 is an IPv6 transition technology where the IPv6 address encodes the originating IPv4 address such that every IPv4 Template:IPaddr has a corresponding, unique IPv6 Template:IPaddr prefix. Because 6to4 relays use the encoded value for determining the end site of the 6to4 tunnel, 6to4 addresses corresponding to IPv4 Martians are not routable and should never appear on the public Internet.
Teredo tunnelingEdit
Teredo is another IPv6 transition technology that encodes the originating IPv4 address in the IPv6 address. However, the encoding format encodes the Teredo server address and tunnel information before the IPv4 client address. Thus there is no definable set of prefixes more specific than Template:IPaddr for Teredo packets with Martian end-site addresses. It is, however, possible to spoof Teredo packets with the Teredo server IPv4 address set to a Martian.
ImplementationEdit
Some of the large router have functionality to filter out specifically for Martian Filtering packet and address.
- Juniper Junos OS has <syntaxhighlight lang="text" class="" style="" inline="1">martians</syntaxhighlight>.<ref>{{#invoke:citation/CS1|citation
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- Cisco IOS does not have Martian Filtering, and uses <syntaxhighlight lang="text" class="" style="" inline="1">ip access-list</syntaxhighlight><ref>{{#invoke:citation/CS1|citation
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- Cisco Small Business has <syntaxhighlight lang="text" class="" style="" inline="1">Martian Addresses</syntaxhighlight><ref>{{#invoke:citation/CS1|citation
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