General technical discussions.
KnowledgeHunter
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Tue May 27, 2008 12:18 pm

Theory. Confining IP hosts completely with netmasks.

Tue May 27, 2008 3:30 pm

I posted earlier about wanting to have only 4 usable hosts on my network.
So I did the math and figured out I needed 255.255.255.250... to my surprise it didn't work...
So I've been told the next best one is 255.255.255.248 - 8 hosts - 6 usable

So I do know how netmasks work sort of...
11111111.11111111.11111111.11111000
------------------------------------------^ Hosts begin here.

So what I tried was a .250 netmask octet for my host portion.

Which would be 11111010 But as somebody pointed out...
------------------------^Hosts still begin here

On my network I wanted only 4 usable IP's, but I have to settle on 6.

Has anybody ever thought of a "Netmask2" or anything like that where admins and the like can confine their hosts to an EXACT number with the netmask...
Wouldn't it be more secure to confine the exact hosts to the exact amount of nodes? This leaves no room for anybody to gain entry and acquire/set a functional IP address.
Why isn't this possible to do? Isn't this technology like 30-40 years old? Hasn't anybody thought of ways to improve it?
I'm not a network engineer by any means, so I'm basically just wondering.

-Insert Flames Below-

KnowledgeHunter
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Tue May 27, 2008 12:18 pm

Tue May 27, 2008 3:39 pm

Okay the formatting got screwed up on my post...

The hosts begin at the first zero...


Sorry

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stretch
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Tue May 27, 2008 4:25 pm

A subnet mask is really just a length of bits: ones on the left, zeros on the right. You can't mix them.

Because of this binary nature, there are only nine possible values for any octet in a subnet mask:

Code: Select all
1111 1111 = 255
1111 1110 = 254
1111 1100 = 252
1111 1000 = 248
1111 0000 = 240
1110 0000 = 224
1100 0000 = 192
1000 0000 = 128
0000 0000 = 0


This sort of segmentation is admittedly rigid, but critical to forming an efficient addressing hierarchy. IPv6 follows the same rules, but masks are expressed in much more user-friendly CIDR notation (/xx).

'

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