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What does separate class C networks refer to?

Discussion in 'BlackHat Lounge' started by davids355, Feb 10, 2012.

  1. davids355

    davids355 Jr. VIP Jr. VIP Premium Member

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    I am trying to build a class C checker in php (it's part of a larger project).

    But just wondering if someone could clarify what needs to be checked?

    Is it just the third octet of the IP that must be different? --as I understand this doesn't always mean it's on a separate network.

    Also as I understand it there are 5 networks classes (a,b,c,d,e), are the other networks ignored... Or am I getting the wrong end of the stick here? :)
     
  2. davids355

    davids355 Jr. VIP Jr. VIP Premium Member

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    *Bump
     
  3. portalweb

    portalweb Supreme Member Premium Member

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  4. Fathom

    Fathom Power Member

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    I'm also curious to know this, but it looks like nobody is sure of the answer.
     
  5. davids355

    davids355 Jr. VIP Jr. VIP Premium Member

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  6. schwagoo

    schwagoo Jr. Executive VIP Jr. VIP Premium Member

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    These two networks are in the same Class-C Subnet (third set of numbers)
    75.75.75.23
    75.75.75.42

    These two networks are in different class-C subnets (different third set of numbers)
    75.75.75.23
    75.75.182.119
     
  7. BassTrackerBoats

    BassTrackerBoats Moderator Staff Member Moderator Jr. VIP

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    It's an Algo, of course it can be gamed.
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    Both of these guys know.

    I don't want to publicly admit they are geniuses but they are.
     
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  8. portalweb

    portalweb Supreme Member Premium Member

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    Please feel free to talk to me about it on IM.
     
  9. davids355

    davids355 Jr. VIP Jr. VIP Premium Member

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    thanks, so it's as easy as checking third octet? (I know subneting is a little more complex as you can be assigned less than a full octet of a class C network, is that relevant?).

    Also what if two IPs/domains are on the same Class B network, would that leave a footprint?
     
  10. davids355

    davids355 Jr. VIP Jr. VIP Premium Member

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    Anyone else have opinion on this?
     
  11. davids355

    davids355 Jr. VIP Jr. VIP Premium Member

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    Bump:)
     
  12. Fathom

    Fathom Power Member

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    I don?t think anyone is going to answer this post.

    The way I see it is that as long as the 3rd octet is different it is a unique c ? class.

    Why? because the following are by class

    Class A = 1 ? 126 - Example 101.xxx.xxx.xxx
    Class B = 128 ? 191 ? Example 154.xxx.xxx.xxx
    Class C = 192 ? 223 ? Example 205.xxx.xxx.xxx
    Class D = 224 ? 239 ? Example 230.xxx.xxx.xxx
    Class E = 240 ? 254 ? Example 249.xxx.xxx.xxx

    So does this mean that these 2 IP?s are on the same C Class: 205.10.231.101 & 205.154.222.85 I would say yes

    Class D and Class E addresses do not get used on the net.

    So the principal of the first 3 octets still apply unless the ip ranges from 192 ? 223 in which case the first octet shouldn?t match.

    This is how I see it but i?m no expert on this so maybe someone can confirm it.
     
  13. davids355

    davids355 Jr. VIP Jr. VIP Premium Member

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    Thanks Fathom. That sounds fair enough, just wanted to hear people's thoughts. I will probably use a ready made script in that case. :)
     
  14. templbi

    templbi Registered Member

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    I also was interested in this and never really new what it meant. Funny how so many people talk about it but I wonder how many actually know what it is. Even after reading above posts it's pretty confusing...:(
     
  15. davids355

    davids355 Jr. VIP Jr. VIP Premium Member

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    Basically all ip networks are made up of two parts - network space and devices.

    The easiest to understand is your standard private network range :
    192.168.1.1-192.168.1.254
    With subnet 255.255.255.0
    The 0 in the last octet of the subnet indicates that the last octet of the ip is designated to devices in the network, so with this address the maximum number of devices you can have is 254. In terms of Seo, you could assume that every address on that network was related because they'd all be on the same class c network (192.168.1.x).

    Class b networks have a bigger portion assigned to devices, example: 180.2.1.1-180.2.254.254
    This means you can have 254x254 devices (64,500) on the same network. And in terms of Seo I guess 180.2.1.1 and 180.2.8.2 would be considered related as they are on the same class B network-- but I'm not sure this is considered a factor as only class C networks seem to be considered relevant.

    Also all that is assuming default subnet masks are being used when in fact a company can be assigned just a portion of a class B network for example -- this is determined by the subnet mask and is actually calculated by converting the ip ranges into binary and then creating a mask also in binary that dictates how many bits of the address are for network and how many for devices, then converting them both back into ip addresses.

    If any of that is wrong feel free to correct:)