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65 lines
2.3 KiB
ReStructuredText
65 lines
2.3 KiB
ReStructuredText
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.. _hooks-ddns-tuning:
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``ddns_tuning``: Tuning DNS updates
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===================================
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This hook library adds support for fine tuning various DNS update aspects.
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Currently is supports procedural hostname generation and an ability to fine
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tune which devices should do the DNS update. The DDNS Tuning hook is a premium
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feature.
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The library, which was added in Kea 2.1.4, can be loaded in a
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similar way to other hook libraries by the ``kea-dhcp4`` and
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``kea-dhcp6`` processes.
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.. code-block:: javascript
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{
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"hooks-libraries": [
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{
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"library": "/usr/local/lib/libdhcp_ddns_tuning.so",
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"parameters": {
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"hostname-expr": "'host-'+hexstring(pkt4.mac,'-')"
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}
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}
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]
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}
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This hook allows generating hostname procedurally, based on an expression.
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The expression can be defined globally in the hook parameters, using `hostname-expr`.
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If defined globally, it will apply to all hosts in all subnets. The expressions can use
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all tokens defined in :ref:`classify`.
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It is also possible to define this parameter in a subnet, using user context mechanism.
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If defined in on subnet level, the expression applies to specific subnet only.
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.. code-block:: javascript
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"subnet4": [{
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"subnet": "192.0.2.0/24",
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"pools": [{
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"pool": "192.0.2.10 - 192.0.2.20",
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} ],
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// This is a subnet-specific user context.
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"user-context": {
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"hostame-expr": "'guest-'+Int8ToText(substring(pkt4.yiaddr, 0,1))+'-' \
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+Int8ToText(substring(pkt4.yiaddr, 1,2))+'-' \
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+Int8ToText(substring(pkt4.yiaddr, 2,3))+'-' \
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+Int8ToText(substring(pkt4.yiaddr, 3,4))",
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"last-modified": "2017-09-04 13:32",
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"description": "you can put anything you like here",
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"phones": [ "x1234", "x2345" ],
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"devices-registered": 42,
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"billing": false
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}
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}]
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.. note::
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Privacy should be taken into consideration when generating a hostname. The hostname is
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usually inserted into the DNS, which is a public system. Exposing identifiers that
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can be used to track devices, such as MAC address, are usually a very bad idea.
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The global expression example used MAC address for simplicity.
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