2019-02-08 19:10:16 +00:00
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====
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DHCP
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====
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DHCP is used to automatically provide clients with an IP address (instead of clients having to set one themselves).
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DHCP is available for both IPv4 and IPv6 clients, referred to as DHCPv4 and DHCPv6, respectively.
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-----------------
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Settings overview
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-----------------
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2019-03-06 17:27:21 +00:00
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DHCPv4 settings can be found at :menuselection:`Services --> DHCPv4`. DHCPv6 settings can be found at :menuselection:`Services --> DHCPv6`.
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2019-02-08 19:10:16 +00:00
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The DHCPv4 submenu further consists of:
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* An entry per interface of general settings, like a toggle to enable/disable DHCPv4 for this interface, DHCP range, DNS servers…
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2019-03-15 13:52:11 +00:00
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* **Relay**: DHCP requests can be “forwarded” to a DHCP server on another interface. This is called relaying.
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2019-02-08 19:10:16 +00:00
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* **Leases**: Shows all IP addresses that are handed out to clients (can be filtered to only show active and static leases).
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* **Log File**: Shows the log file of the DHCPv4 server.
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The DHCPv6 submenu further consists of:
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2019-03-15 13:52:11 +00:00
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* **Relay**: DHCP requests can be “forwarded” to a DHCP server on another interface. This is called relaying.
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2019-02-08 19:10:16 +00:00
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* **Leases**: Shows all IP addresses that are handed out to clients (can be filtered to only show active and static leases).
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------------
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Using DHCPv4
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------------
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A typical DHCPv4 usage scenario is using it on your LAN with an IP range of 192.168.1.x, where x can be a number from 1
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through 254. This means a subnet mask of 255.255.255.0. The range can also be written as 192.168.1.0/24. (The “1” in
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the third group can also be another number, and there are also other ranges available for private use. These are
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described in `RFC 1918 <https://tools.ietf.org/html/rfc1918#section-3>`_.)
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The LAN IP of the OPNsense device that serves DHCP to the LAN should fall in the same DHCP IP range. Typically, it gets
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2019-03-15 13:52:11 +00:00
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the address ending in .1 (so 192.168.1.1 in this example).
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2019-02-08 19:10:16 +00:00
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2019-03-06 17:27:21 +00:00
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To set the LAN IP, go to :menuselection:`Interfaces --> [LAN]`, set “IPv4 Configuration Type” to “Static”, and under
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2019-02-08 19:10:16 +00:00
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“Static IPv4 configuration”, set “IPv4 address” to ``192.168.1.1`` and the subnet dropdown to “24”. Then click Save.
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2019-03-15 13:52:11 +00:00
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To set the DHCP settings, go to :menuselection:`Services --> DHCPv4 --> [LAN]`. Under “Gateway”, put ``192.168.1.1``. Under range,
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2019-02-08 19:10:16 +00:00
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put ``192.168.1.100`` as the start address and ``192.168.1.200`` as the end address. Then click Save. After saving,
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2019-03-15 13:52:11 +00:00
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click the “Apply Settings” button.
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-------------
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DHCP relaying
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-------------
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DHCP relaying is the forwarding of DHCP requests received on one interface to the DHCP server on another. DHCP
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relaying is available for both DHCPv4 and DHCPv6. The DHCPv4 settings can be found at
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:menuselection:`Services --> DHCPv4 --> Relay`. The DHCPv6 settings can be found at
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:menuselection:`Services --> DHCPv6 --> Relay`.
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When setting up DHCP relaying (both DHCPv4 and DHCPv6 relaying have the same settings), the following options are
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available:
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+-----------------------+----------------------------------------------------------------------------------------------+
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| Setting | Explanation |
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+=======================+==============================================================================================+
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| Enable | |
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+-----------------------+----------------------------------------------------------------------------------------------+
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| Interface(s) | Which interfaces to apply relaying to. Only interfaces with an IP can be selected. |
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+-----------------------+----------------------------------------------------------------------------------------------+
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| Append circuit ID and | If this is checked, the DHCP relay will append the circuit ID (interface number) and the |
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| agent ID to requests | agent ID to the DHCP request. |
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+-----------------------+----------------------------------------------------------------------------------------------+
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| Destination servers | A comma separated list of IPs to which the requests should be forwarded. |
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+-----------------------+----------------------------------------------------------------------------------------------+
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