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<strong>Discussion</strong><br />

Martian addresses are prefixes reserved for a specific purpose and not subject to<br />

future allocation by the IANA. You should never see traffic from these prefixes; if<br />

you do, it generally indicates that a system somewhere on the network is misconfigured.<br />

By default, the JUNOS software ignores all martian addresses and does not<br />

install them in the routing table. The JUNOS software maintains the following martian<br />

addresses by default:<br />

aviva@router1> show route martians<br />

inet.0:<br />

0.0.0.0/0 exact -- allowed<br />

0.0.0.0/8 orlonger -- disallowed<br />

127.0.0.0/8 orlonger -- disallowed<br />

128.0.0.0/16 orlonger -- disallowed<br />

191.255.0.0/16 orlonger -- disallowed<br />

192.0.0.0/24 orlonger -- disallowed<br />

223.255.255.0/24 orlonger -- disallowed<br />

240.0.0.0/4 orlonger -- disallowed<br />

...<br />

inet6.0:<br />

::1/128 exact -- disallowed<br />

These correspond to the all-zeros and all-ones classful network numbers, as well as<br />

the Class E network space. All of the former addresses were reserved by IANA (and<br />

many still are), and routing for the latter is undefined.<br />

There is no permanent list of martian addresses because the address spaces that<br />

IANA chooses to reserve and make available for allocation change over time. Some<br />

martian addresses are not included in the JUNOS defaults, and some of the address<br />

blocks included in the JUNOS software default martian list have since been made<br />

available for allocation by IANA (see RFC 3330).<br />

This recipe adds an address to the martian list on a router. Look at the martian<br />

routes in the routing table to verify that the address has been added:<br />

aviva@router1> show route martians table inet.0<br />

inet.0:<br />

0.0.0.0/0 exact -- allowed<br />

0.0.0.0/8 orlonger -- disallowed<br />

127.0.0.0/8 orlonger -- disallowed<br />

128.0.0.0/16 orlonger -- disallowed<br />

191.255.0.0/16 orlonger -- disallowed<br />

192.0.0.0/24 orlonger -- disallowed<br />

223.255.255.0/24 orlonger -- disallowed<br />

240.0.0.0/4 orlonger -- disallowed<br />

1.0.0.0/0 through 1.0.0.0/32-- disallowed<br />

The disallowed keyword in the output means that the route is treated like a martian<br />

and is blocked.<br />

This is the Title of the Book, eMatter Edition<br />

Copyright © 2008 O’Reilly & Associates, Inc. All rights reserved.<br />

Adding Martian Addresses | 273

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