| TheIP_Adress.shtml | |
| IP ADDRESS STRUCTURE: Note: the terms multicast address and MSB are explained at the end. Every station on a PSN (packet switched network) that is based on the TCP/IP protocol (your computer is one, for example. Yes, we're referring to a host that is connected to the net) must have an IP address, so it can be identified, and information can be relayed and routed to it in an orderly fashion. An IP address consists of a 32 bit logical address. The address is divided into two fields: 1) The network address: 2) The host address: IP address structure: ---.---.---.--- ^ ^ Every " --- " = 8 bits. with 8 bits you can present from 0-255 . (binary=(2 to the power of 8)-1)
N=NETWORK , h=HOST . Notice the address range 127.X.X.X. These addresses are assigned to internal
use to the network device, and are used as an application tool only. For
example: 127.0.0.1, the most common one, is called the loopback address
- everything sent here goes directly back to you, without even traveling
out on the wire. Also, some IPs are reserved for VPNs - Virtual Private
Networks. These are local area networks over wide area networks that use
the Internet Protocol to communicate, and each computer inside the network
is assigned with an IP address. So, suppose a certain computer wants to
send a data packet to another host on the network with the IP 'x', but
there's also another host on the Internet that has the same IP - what
happens now? So this is why you cannot use these and other forms of reserved
IPs on the Internet. Distinguishing different groups: You have to compare the first byte on the left in the address as follows:
1) Multicast: The membership of a host group is dynamic; that is, hosts may join and leave groups at any time. There is no restriction on the location or number of members in a host group. A host may be a member of more than one group at a time. A host need not be a member of a group to send datagrams to it. A host group may be permanent or transient. A permanent group has a well-known, administratively assigned IP address. It is the address, not the membership of the group, that is permanent; at any time a permanent group may have any number of members, even zero. Those IP multicast addresses that are not reserved for permanent groups are available for dynamic assignment to transient groups which exist only as long as they have members. Internetwork forwarding of IP multicast datagrams(ip packets)is handled by "multicast routers" which may be co-resident with, or separate from, internet gateways. A host transmits an IP multicast datagram as a local network multicast which reaches all immediately-neighboring members of the destination host group. If the datagram has an IP time-to-live greater than 1, the multicast router(s) attached to the local network take responsibility for forwarding it towards all other networks that have members of the destination group. On those other member networks that are reachable within the IP time-to-live, an attached multicast router completes delivery by transmitting the datagram(ip packet) as a local multicast. *if you donot understand the above do not worry, it is complicated and dry but reread it and read it again get a dictionary if it helps. Hacking is not easy. 2) MSB: Most Significent Bit:
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| Credits: |
| 21/04-2000. Re-edited 6/21/01. Published on Blacksun Research Facility {BSRF} - Written by WATER, edited by snider, and corrections made by Rek. |