# Valid Public IP Range



## glj12 (Apr 6, 2007)

I have been trying to figure out what denotes a proper public IP range. Whenever I do a google search, I only retrieve information on local/private IP addresses.

Such as,
68.1.1.1 - 68.1.245.245 is apparently partially valid according to a program that I wrote, but I would like a definitive answer.

I would assume that there is some sort of rule to define valid public addresses. Anyone care to help me out?


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## wisdum (Dec 1, 2005)

Im sure you're searches have been inconclusive because of the wording. Technically, a "public" address would be an address that anyone can use. Such as: 192.168.x.y

These public address that anyone can use are "classful" or based on older Class A,B, and C IP networks.

These "public" ranges would be the 10.x.y.z network (/slash 8)
172.16.x.y - 172.22.x.y (i could be wrong, off the top of my head)
and 192.168.x.y (/slash 16)

These are reserved and have no global significance.

Does that help?


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## glj12 (Apr 6, 2007)

That does help partially, but what defines an IPV4 address to be valid? (Minus the private usage ones) such as mine, 69.211.246.98.

Like, what range is considered valid to ISP's?


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## wisdum (Dec 1, 2005)

Everything (kinda, but not really) is public or has global significance as long as it is not in the private range. So, if your IP is 69.x.y.z that is a global address (public)

There is a few exceptions on the really high end range for multi/unicast/research but i think that is like 248.x.y.z or so.

here is a link that may help clarify for you.

Good Luck!


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## wisdum (Dec 1, 2005)

Oh,

and as far as ISPs go: They were giving a range of global addresses from the InterNIC which is an organization that controls all IP addresses.

So, if you wanted to have a global IP on, say a web server, you would get that specific IP or range of IP's (known as a subnet) for your organization.

Sorry, i should have included that on my last post.


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## glj12 (Apr 6, 2007)

So technically one could ping from starting with 1.1.1.1 - 255.255.255.255, and the low range could possibly bring up an IP address such as 2.56.32.45? I was curious what is the lowest possible IP address there is to ping that might conceivably respond publicly.

Either way, I will go ahead and read that, thanks for the help!

Edit: Ah, I was too slow to post, just saw the third post of yours. I'll look that up, thanks!


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## wisdum (Dec 1, 2005)

If you really wanted to learn a lot about it:

Do research on Subnetting, Classful vs Classless IP networks, and CIDR.

Those topics will help build a better understanding of how IP networks work, and pass traffic.

I don't have any specific site that i can direct you toward, but im sure a bit of google magic will come up with something!


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## StumpedTechy (Jul 7, 2004)

ISPs get their IPs from different organizations -

American Registry for Internet Numbers
Réseaux IP Européens Network Coordination Centre
Latin American and Caribbean Internet Addresses Registry
Asia Pacific Network Information Centre

Those delegate and coordinate the IP's that the different ISP's have. Basically your ISP has given you 69.211.246.98 so your ISP has gone to one of the 4 above facilities (depending on its location) and they gave them a block of IP's this block of IPs one of them was the one you have. You can usually safely assume machines within the same "blocK" will be with the same provider but thats about as far as you can take it.


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## glj12 (Apr 6, 2007)

Heheh, will do. Many thanks for all the help guys!

Note to StumpedTechy: I never new that there were only 4 official organizations that delegated what each ISP gets. Pretty interesting. I'll go ahead and read up on it now.


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## wisdum (Dec 1, 2005)

Thanks stumped for the international clarification!! 

You are a great resource to this forum!


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## TerryNet (Mar 23, 2005)

Public IP addresses are those not designated as private. wisdum had the right idea, but has private and public backwards. 

Private IP Address:

An IP address is considered private if the IP number falls within one of the IP address ranges reserved for private uses by Internet standards groups. These private IP address ranges exist: 
10.0.0.0 through 10.255.255.255
169.254.0.0 through 169.254.255.255 (APIPA only)
172.16.0.0 through 172.31.255.255
192.168.0.0 through 192.168.255.255


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## coulterp (Oct 20, 2003)

glj12 said:


> Heheh, will do. Many thanks for all the help guys!
> Note to StumpedTechy: I never new that there were only 4 official organizations that delegated what each ISP gets. Pretty interesting. I'll go ahead and read up on it now.


According to RIPE there are five organisations, see: http://www.ripe.net/info/resource-admin/index.html

"Understanding IP Addressing: Everything You Ever Wanted To Know" available http://www.3com.com/other/pdfs/infra/corpinfo/en_US/501302.pdf should help.


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## O111111O (Aug 27, 2005)

Anything that's not allocated from IANA is considered private or BOGON.

If you're interested to see what should be available, the easy way to answer this is to see what SHOULDN'T be in anybody's route table.

Cymru keeps a good public BOGON list.

http://www.cymru.com/Documents/bogon-dd.html

In essence, if you look up any of the CIDR's in this list, you'll see that they're IANA reserved for either RFC1918, or are held for future allocations.


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## StumpedTechy (Jul 7, 2004)

Interesting I didn't know there was an afrinic.

To be honest I have not referenced anything outside of arin as I don't have any need for international IPs.


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## O111111O (Aug 27, 2005)

wisdum said:


> A+/Net+ - screw that!
> MCSE/Cisco - screw that too!
> Sun/Solaris - What company do you work for?
> 
> ...


Nice, a bit harsh, and I don't know that I'd lump MCSE/Cisco together. Also, 1998 called and wanted it's technology back (Solaris)


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