rfuller@3x.com wrote:
I have been reading Cisco's "Essential IOS Features Every ISP Should Consider" document and came across a section called Martian and RFC1918 networks. It is discussing different bogus or reserved networks that should be filtered by every ISP. In the list are some addresses I thought were legal and after checking the ARIN Whois database, some of them seem to be. Can anyone give me some additional information as to the need to filter the following networks:
Some of these are indeed questionable. I recommend using Bill Manning's draft on this subject (draft-manning-dsua-01.txt) as a guide, rather than Cisco's document. Page 27 of Cisco's document has a sample access-list which does match Bill's document. Page 59 of the document has the list you saw and were concerned about. It claims the information comes from the NANOG list. Hmmm...
1.0.0.0 reserved for IANA 19.255.0.0 this belongs to Ford 59.0.0.0 reserved for IANA 129.156.0.0 this belongs to SUN
169.254.0.0 IANA use for local link numbers???
169.254/16 should never be routed. It's used for self assigned addresses, and is useful in small networks especially. Win98 takes advantage of this if DHCP fails to find a server. It allows a small cluster of systems to select unique IP addresses, and in the case of Windows, they'll then talk Netbios over IP on that. It eliminates the need to use Netbeui, which in itself is a good thing.
192.0.2.0 reserved for IANA
192.0.2/24 is set aside for use in documentation and examples. By ensuring this block is not routed, folks who type the exact values from their documentation don't screw up someone else's network.
192.5.0.0 no ARIN match 192.9.200.0 no ARIN match 192.9.99.0 this belongs to SUN
If you can elaborate on what they are used for and if any problems would arise from filtering these networks, it would be appreciated. If you could also please include where you found the information, I would appreciate it. Some of them belong to companies, so why would you filter them? Are they development networks for Ford and SUN? Are there any other martian networks that should be filtered?
Lots of folks used to set up their Sun workstations on private networks using Sun's IP space, 'cause that's what was in the Sun documentation. The only thing I can figure is the other blocks in the example must be ones that were frequently used in documentation and got used in a lot of private networks that later connected to the public network. Anyone have better insight into these? -- ----------------------------------------------------------------- Daniel Senie dts@senie.com Amaranth Networks Inc. http://www.amaranthnetworks.com