Setting additional DHCP configuration parameters
This feature is advanced and should be used only by expert users in special situations.
The vRouter DHCP server commands provide a set of commonly used DHCP server features. However, many additional features are available. Information regarding the available DHCP server features are located on the dhcpd.conf man page. To access it, type the following at the Vyatta command prompt:
man dhcpd.conf
To access these additional features, use one of the following commands, depending on the required scope of the feature. The commands are listed from widest to narrowest scope.
- service dhcp-server global-parameters params
- service dhcp-server static-mapping mapname static-mapping-parameters params
- service dhcp-server shared-network-name name shared-network-parameters params
- service dhcp-server shared-network-name name subnet ipv4net subnet-parameters params
The precedence of scope of these commands is from narrowest to widest. That is, if more than one command is specified and a given host address falls within the scope of both, it is governed by parameters specified in the command with the narrowest scope.
Multiple parameter strings can be specified. Each parameter string that is specified adds a separate line to the dhcpd.conf file.
Note that no validation is done by the vRouter before passing the parameter string from these commands to the DHCP server process (dhcpd). Because of this lack of validation, it is imperative that the syntax described in the dhcpd.conf documentation be strictly followed. Failure to do so could result in a failure of the DHCP server. It is advisable to check the system log for errors when using these parameter strings. In addition, the show system processes command can be used to determine if the dhcpd process is still running.
The following example shows how the additional DHCP server parameters can be accessed. To configure additional DHCP server parameters, perform the following steps in configuration mode.
Step |
Command |
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Enable the DHCP server and define an option that does not already have a keyword defined in the dhcpd process. See the dhcpd man page for further information. |
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Specify the value to be used for the option for all shared networks, subnets, and static mappings defined in the DHCP server configuration. |
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Specify an IP address to statically map to a host with a specific MAC address. |
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Specify the MAC address of a host to be statically mapped to an IP address. |
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Override the global value of the parameter defined previously for a specific host. |
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Specify that the DHCP server is authoritative for the specified shared network. |
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Specify the subnet and address pool to use. |
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Commit the changes. |
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Show the configuration. |
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