An IP address (Internet Protocol address) is a unique address that certain
electronic devices use in order to identify and communicate with each other on a
computer network utilizing the Internet Protocol standard (IP)—in simpler terms,
a computer address. Any participating network device—including routers,
computers, time-servers, printers, Internet fax machines, and some telephones
can have their own unique address.
In other words, the IP address acts as a locator for one IP device to find
another and interact with it. It is not intended, however, to act as an identifier
that always uniquely identifies a particular device.
An IP address can also be thought of as the equivalent of a street address or a
phone number (compare: VoIP (voice over (the) Internet protocol)) for a
computer or other network device on the Internet. Just as each street address
and phone number uniquely identifies a building or telephone, an IP address
can uniquely identify a specific computer or other network device on a network.
An IP address differs from other contact information, however, because the
linkage of a user's IP address to his/her name is not publicly available
information.
Further, an IP address is not necessarily linked, in a persistent way, to a
physical location or even data link layer address.
In the past, an IP address could be considered a unique identifier of a
particular IP host, in addition to being a locator. When it was usable as an
identifier, it was static, and it was assumed to be globally unique from end to
end of the Internet.
In current practice, an IP address is less likely to be an identifier, due to
technologies such as:
Dynamic assignment, as with an address that is assigned by the access device
by which the user's host connects over a dial-up telephone line or by a set-top
box for an IP over cable network. However the network provider maintains a
database of which IP address was assigned to which access port on dial-up, or
MAC address on LANs or broadband networks. This information, assuming it is
available to the investigator, may help to identify the computer, although that is
unlikely if it was a dial-up connection where the identifier is of the dial-in port, not
the
computer itself. More extensive forensic work, with access to telephone records,
may identify the calling telephone, although that may itself be a "cutout" on
the way to the real telephone. Network address translation, where the address
visible on the Internet is the "outside" of a device that maps it to a
completely different and hidden address on the "inside".
Static and dynamic IP addresses.
A Static IP address is where a computer uses the same address every time, as
opposed to situations where the user IP address changes frequently, when a
user logs on to a network by dial-up or on shared residential cable. Static
addressing is essential in some infrastructure situations, such as finding the
Domain Name Service directory host that will translate names to numbers.
Static addresses are convenient, but not absolutely necessary, to locate servers
inside an enterprise. An address obtained from a DNS server comes with a
lifetime argument, after which it should be looked up to confirm that it has not
changed. Addresses do change as a result of network administration (RFC
2072).
This contrasts with a Dynamic IP address, wherein an IP address is assigned to
a computer, usually by a remote server which is acting as a Dynamic Host
Configuration Protocol server. IP addresses assigned using DHCP may change
depending on the addresses available in the set scope. Dynamic IP Addresses
assigned by Dynamic Host Configuration Protocol servers are used because it
reduces the administrative burden of assigning static addresses within a
network.
IP address translation
IP addresses can appear to be shared by multiple client devices either because
they are part of a shared hosting web server environment or because a network
address translator (NAT) or proxy server acts as an intermediary agent on
behalf of its customers, in which case the real originating IP addresses might be
hidden from the server receiving a request. A common practice is to have a NAT
hide a large number of IP addresses, in the private address space defined by
RFC 1918, an address block that cannot be routed on the public Internet. Only
the "outside" interface(s) of the NAT need to have Internet-routable addresses.
Most commonly, the NAT device maps TCP or UDP port numbers on the outside
to individual private addresses on the inside. Just as there may be site-specific
extensions on a telephone number, the port numbers are site-specific
extensions to an IP address.
IP addresses are managed and created by the Internet Assigned Numbers
Authority (IANA). The IANA generally allocates super-blocks to Regional Internet
Registries, who in turn allocate smaller blocks to Internet service providers
and enterprises.
Attributes and Credits
The information and facts supplied on this subject
derive from http://en.wikipedia.org/wiki/Main_Page
electronic devices use in order to identify and communicate with each other on a
computer network utilizing the Internet Protocol standard (IP)—in simpler terms,
a computer address. Any participating network device—including routers,
computers, time-servers, printers, Internet fax machines, and some telephones
can have their own unique address.
In other words, the IP address acts as a locator for one IP device to find
another and interact with it. It is not intended, however, to act as an identifier
that always uniquely identifies a particular device.
An IP address can also be thought of as the equivalent of a street address or a
phone number (compare: VoIP (voice over (the) Internet protocol)) for a
computer or other network device on the Internet. Just as each street address
and phone number uniquely identifies a building or telephone, an IP address
can uniquely identify a specific computer or other network device on a network.
An IP address differs from other contact information, however, because the
linkage of a user's IP address to his/her name is not publicly available
information.
Further, an IP address is not necessarily linked, in a persistent way, to a
physical location or even data link layer address.
In the past, an IP address could be considered a unique identifier of a
particular IP host, in addition to being a locator. When it was usable as an
identifier, it was static, and it was assumed to be globally unique from end to
end of the Internet.
In current practice, an IP address is less likely to be an identifier, due to
technologies such as:
Dynamic assignment, as with an address that is assigned by the access device
by which the user's host connects over a dial-up telephone line or by a set-top
box for an IP over cable network. However the network provider maintains a
database of which IP address was assigned to which access port on dial-up, or
MAC address on LANs or broadband networks. This information, assuming it is
available to the investigator, may help to identify the computer, although that is
unlikely if it was a dial-up connection where the identifier is of the dial-in port, not
the
computer itself. More extensive forensic work, with access to telephone records,
may identify the calling telephone, although that may itself be a "cutout" on
the way to the real telephone. Network address translation, where the address
visible on the Internet is the "outside" of a device that maps it to a
completely different and hidden address on the "inside".
Static and dynamic IP addresses.
A Static IP address is where a computer uses the same address every time, as
opposed to situations where the user IP address changes frequently, when a
user logs on to a network by dial-up or on shared residential cable. Static
addressing is essential in some infrastructure situations, such as finding the
Domain Name Service directory host that will translate names to numbers.
Static addresses are convenient, but not absolutely necessary, to locate servers
inside an enterprise. An address obtained from a DNS server comes with a
lifetime argument, after which it should be looked up to confirm that it has not
changed. Addresses do change as a result of network administration (RFC
2072).
This contrasts with a Dynamic IP address, wherein an IP address is assigned to
a computer, usually by a remote server which is acting as a Dynamic Host
Configuration Protocol server. IP addresses assigned using DHCP may change
depending on the addresses available in the set scope. Dynamic IP Addresses
assigned by Dynamic Host Configuration Protocol servers are used because it
reduces the administrative burden of assigning static addresses within a
network.
IP address translation
IP addresses can appear to be shared by multiple client devices either because
they are part of a shared hosting web server environment or because a network
address translator (NAT) or proxy server acts as an intermediary agent on
behalf of its customers, in which case the real originating IP addresses might be
hidden from the server receiving a request. A common practice is to have a NAT
hide a large number of IP addresses, in the private address space defined by
RFC 1918, an address block that cannot be routed on the public Internet. Only
the "outside" interface(s) of the NAT need to have Internet-routable addresses.
Most commonly, the NAT device maps TCP or UDP port numbers on the outside
to individual private addresses on the inside. Just as there may be site-specific
extensions on a telephone number, the port numbers are site-specific
extensions to an IP address.
IP addresses are managed and created by the Internet Assigned Numbers
Authority (IANA). The IANA generally allocates super-blocks to Regional Internet
Registries, who in turn allocate smaller blocks to Internet service providers
and enterprises.
Attributes and Credits
The information and facts supplied on this subject
derive from http://en.wikipedia.org/wiki/Main_Page
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