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.. _ch-install-on-linux-ip-restriction:

IP Address Restriction
----------------------

.. contents:: |RST_TABLE_OF_CONTENTS|
   :depth: 2
   :local:


|PRODUCT_NAME| uses :ref:`CIDR Notation <ch-install-on-linux-cidr>` for IP
address restriction where needed.

.. _ch-install-on-linux-cidr:

CIDR Notation
~~~~~~~~~~~~~

`Classless Inter-Domain Routing <https://tools.ietf.org/html/rfc4632>`__
(CIDR) is developed in the 1990s as a standard scheme for routing
network traffic across the Internet.

CIDR notation is a syntax for specifying IP addresses and their
associated prefix size, the latter being equivalent to the number of
leading 1 bits in the routing prefix mask. The notation starts with an
IP address expressed according to the standards of IPv4 or IPv6 [1]_.
It is followed by a separator character, the slash (/) character, and
the prefix size expressed as a decimal number.

Some examples:

-  ``172.16.0.0/24`` represents the given IPv4 address and its
   associated routing prefix ``172.16.0.0``, or equivalently, its subnet
   mask ``255.255.255.0``. This represents the host address range
   ``172.16.0.0`` - ``172.16.0.255``.

-  CIDR ``192.168.1.40/32`` represents the single IPv4 address
   ``192.168.1.40``.

-  CIDR ``2021:661:4cc6:1:5561:96ff:ca11:d4a/128`` represents the single
   IPv6 address ``2021:661:4cc6:1:5561:96ff:ca11:d4a``.

-  CIDR ``2021:661:4cc6:1:5561:96ff:ca11:d00/120`` represents a block
   size of ``256`` with First IP ``2021:661:4cc6:1:5561:96ff:ca11:d00``
   and a Last IP ``2021:661:4cc6:1:5561:96ff:ca11:dff`` .


.. [1]
   CIDR notation for IPv6 is described in
   `RFC 4291 <https://tools.ietf.org/html/rfc4291#section-2.3>`__.


.. _ch-install-on-linux-cidr-set:

CIDR Set
~~~~~~~~

For |PRODUCT_NAME| Use Only we define a CIDR Set as a concatenation of
single :ref:`CIDR notations <ch-install-on-linux-cidr>` separated by any
of the characters *space*, *comma* or *semicolon*.