Page 1 of 2 12 LastLast
Results 1 to 10 of 11

Thread: ip address classes question

  1. August 6th, 2003, 05:35 AM #1
    sodiumwater
    sodiumwater is offline
    Junior Member
    Join Date
    Aug 2003
    Posts
    2

    ip address classes question

    I am wondering if it is possible to use a class B or C address ip as a class A. I know about subnet masks and stuff. But im wondering if you could use a network address such as 192.0.0.0 and subnet mask 255.0.0.0, and if there is a way it could work.

    If it won't work is it just because the OS will give an error or the router/switch won't exept those configurations. Im thinking if you can subnet, and barrow bits why couldn't you take away bits.
    Reply With Quote Reply With Quote
  2. August 6th, 2003, 05:37 AM #2
    fl34bit3
    fl34bit3 is offline
    Senior Member
    Join Date
    Mar 2003
    Posts
    301
    No I dont believe it will work each class has their ip range and respective subnet mask.

    PeacE
    -BoB
    #!/usr/local/bin/perl -s-- -export-a-crypto-system-sig -RSA-in-3-lines-PERL
    ($k,$n)=@ARGV;$m=unpack(H.$w,$m.\"\\0\"x$w),$_=`echo \"16do$w 2+4Oi0$d*-^1[d2%
    Sa2/d0<X+d*La1=z\\U$n%0]SX$k\"[$m*]\\EszlXx++p|dc`,s/^.|\\W//g,print pack(\'H*\'
    ,$_)while read(STDIN,$m,($w=2*$d-1+length($n||die\"$0 [-d] k n\\n\")&~1)/2)
    Reply With Quote Reply With Quote
  3. August 6th, 2003, 05:46 AM #3
    cheyenne1212
    cheyenne1212 is offline
    Senior Member
    Join Date
    Feb 2003
    Location
    Memphis, TN
    Posts
    3,747
    The IP address 192.0.0.0 must have a subnet mask of 255.255.255.0 then from there you can break it donw futher from that same IP class. So I agree with fl34bit3 on this one, I don't believe you can subnet a class c or b into a class a.
    =
    Reply With Quote Reply With Quote
  4. August 6th, 2003, 08:31 AM #4
    Negative
    Negative is offline
    Banned
    Join Date
    Aug 2001
    Location
    Yes
    Posts
    4,424
    *Moved from AntiOnline: How do I?*
    Reply With Quote Reply With Quote
  6. August 6th, 2003, 09:17 AM #5
    Ghost_25inf
    Ghost_25inf is offline
    IT Specialist Ghost_25inf's Avatar
    Join Date
    Sep 2001
    Location
    Michigan
    Posts
    648

    ah yes IP ranges

    Yes you can set any number to your own class C network except for 0, 1, and 255 theses are left open for broadcast. Now dont get me wrong im not saying your isp or your cable provider will provide you with an ip of 10.51.5.13 or let you run a static address, when its running a class B network. But if you are running a router or AP or any other device which allows you to set the subnet mask and the ip range then you can absolutely run your class B or C network with an A address. I would also like to point out that I have seen it with my own eyes and found this very odd myself. also if you think about it, this would make a very good security tactic.
    S25vd2xlZGdlIGlzIHBvd2VyIQ
    Reply With Quote Reply With Quote
  7. August 6th, 2003, 10:04 PM #6
    spetard
    spetard is offline
    Junior Member
    Join Date
    Jul 2003
    Posts
    17

    Lightbulb

    sure you can its called CIDR ( Classless inter-Domain Routing) or Supernetting. Its just like Sub Netting But you go the other way for a more detailed explination you can look and any CCNP (Sybex or Cisco) BSCI ( Building Scaleable Cisco Internetworks) book or try this link.
    http://www.firewall.cx/supernetting-chart.php
    Reply With Quote Reply With Quote
  8. August 6th, 2003, 10:35 PM #7
    cheyenne1212
    cheyenne1212 is offline
    Senior Member
    Join Date
    Feb 2003
    Location
    Memphis, TN
    Posts
    3,747
    Guess I was wrong.

    I'm not that advanced yet. I will be in a couple years though.

    I'll have to read about that stuff.
    =
    Reply With Quote Reply With Quote
  9. August 7th, 2003, 12:41 AM #8
    gunit0072003
    gunit0072003 is offline
    Senior Member
    Join Date
    Aug 2003
    Posts
    205
    As stated before by "spetard" this concept is called CIDR (classless interdomain routing)
    used by routing protocols only, most commonly the famous BGP4 (Internet standard routing protocol)

    I would like to know why you want to do such a thing.
    I hope its not because you think you may get more addresses because
    that is not the case at all.

    Think about it, if you plan on using these addresses on a private network
    (not part of the Internet) then you have more than enough RFC1918 addresses
    to play with.

    If you plan on using the addresses on the public network(Internet), you
    will not be able to, because when you apply for an IP address or block
    you get only the class A, B or C addresses/blocks ex. (X.0.0.0, X.X.0.0 and X.X.X.0)
    Using your example, you would never get just a 192 address from the public domain.

    For this reason, as far as I know, unless someone out there can correct me, all
    TCP/IP stacks on pc based OS's do not support CIDR and for a very good reason.
    Why would you want to. Even if some stack out there did, there would be no usefull
    purpose for it.

    CIDR again is a concept that is used by routing protocols..
    All Internet routers run a standard routing protocol
    called BGP4(version 4) that supports CIDR. The reason ISP's use CIDR is to
    summarize the routes in the routing table.
    Currently there are over 120K routes and growing exponentially


    Hope this helps....

    Soon to come for anyone new to IP, I am planning on posting a very good tutorial
    It Will be a good intro on Ip subnetting and summarization.
    Reply With Quote Reply With Quote
  11. August 7th, 2003, 03:53 AM #9
    Sgear17
    Sgear17 is offline
    Banned
    Join Date
    Jul 2002
    Posts
    110
    sodiumwater I i recommned you go to google then there a cisco PDF file that give an information about the whole TCP/IP Protocol thing i dont have the address (exac t) just PM me if you want it OKIE
    Reply With Quote Reply With Quote
  12. August 7th, 2003, 06:26 AM #10
    alphabetarian
    alphabetarian is offline
    Senior Member
    Join Date
    Jul 2002
    Posts
    117
    Let's not forget about the fact that B and C class address ranges have significantly less host address available than Class A's do. Class A's have 16 million+, B's have 65,000+, and C's have 255. This to me would be the biggest reason why you wouldn't be able to do it.
    Reply With Quote Reply With Quote
« Previous Thread | Next Thread »

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

Forum Rules