dhcpd command (DHCP Server)

Address scope

Allows to create a scope, even if a scope cannot be attached to some interface, it is not deleted.

• "SCOPE_NAME" – scope name. It is not case-sensitive and must be unique. If scope name contains spaces, server will automatically substitute them with "underscore" sign (_).
• "INTERFACE" – name of the network interface with which this scope will be attached (allowed interface). If "*" is specified as interference, that means that this scope can be attached to all suitable network interfaces. Suitable network interface is an interface which contains a subnet of IP-addresses (aliases) that includes starting and ending IP-addresses of the scope.
• "START_IP" / "END_IP" – starting and ending IP-addresses of the scope correspondingly. When attaching to network interface, it is checked if a range of this scope does not intersect (and is not included) within another scope that might be attached to this interface. When IP-addresses are assigned to clients, only those scopes can be used which are attached to the same network interface through which requests from clients are accepted.

Scope of IP-addresses has clients class filter. If a client in its request submits its class, a server is able to give an IP-address only from those scopes which are connected to interface through which requests from clients are accepted. and which have client’s class specified in their class filter. Class filter is a set of client vendor class id from which it is allowed to give a lease for IP-addresses from the scope. In order to create a class filter for a scope, one should add one or more client vendor class id. This parameter is used to add a client vendor class id to the scope.

• "SCOPE_NAME" – name of the scope to which client vendor class id is added ("CLIENT_CLASS_ID").
• "CLIENT_CLASS_ID" – a set of characters of variable length (up to 255 characters). If this parameter contains spaces it should be specified in quotes. This "<CLIENT_CLASS_ID>" is compared to what client submits when requests for IP-address lease. If client submitted a class which does not present in any of scope’s filters or a client did not submit any class name, only scopes with no class filters can be used for IP-address lease.

Sets up exceptions into scope range of addresses. Exceptions are range of addresses which belong to the scope but are not given to DHCP server clients.

• "SCOPE_NAME" – scope name to which we add exceptions.
• "START_IP" and "END_IP" – starting and ending addresses of an exception. Exception’s range should not intersect (or belong) with any of previous exceptions assigned to this scope. Exception"s range should belong to the scope.

Deletes exception from the scope.

Creates a reservation for the scope. The scope reservation is using to reserve an IP-address for a specific client.

• "SCOPE_NAME" – name of the scope to which reservation is added.
• "CLIENT_ID" – client identifier.
• "CLIENT_IP" –  IP-address which will be given to this client. Scope reservations are saved in configuration database of the server and are identified by scope name and client’s identifier.

Adds a set of options for the scope.

• • "SCOPE_NAME" – name of the scope to which options are added.
  • "OPTION_NAME" and "OPTION_VALUE" – the description of these parameters is in paragraph "Configuration opions".

Adds a set of options for the resrvation in the scope.

• • "SCOPE_NAME" – scope name for which reservation an option value need to be defined.
  • "CLIENT_ID" – reservation client identifier. If this option with the same name was defined, the value will be changed to the one specified in this command.
  • "OPTION_NAME" and "OPTION_VALUE" – the description of these parameters is in paragraph "Configuration opions".

Deletes options for the reservation in the scope.

Displays the scope status. In the paragraph "Address Time" you can find decoding IP-address values for this option.

• "NAME" – scope name for which status need to be displayed. If "*" is specified as a name of scope, status for all scopes will be displayed.

scope <SCOPE_NAME|*> show declinehistory

delete scope <SCOPE_NAME>

Network interfaces

Displays network interfaces information. After its start, the server automatically detects all network interfaces which are suitable for serving DHCP clients. Suitable interface is an interface connected to a multiple-access network with broadcast support (including VLAN support). In server database each interface is identified by its name which was assigned to it while registration in WANFleX OS core.

• "INTERFACE" – network interface name which information is required. If "*" is specified instead of interface name, all interfaces information is printed. Command output is a structured list.

Assigns a set of options for the interface.

• "INTERFACE" – the name of the interface options are applied for.
• "OPTION_NAME" and "OPTION_VALUE" – the description of these parameters is in paragraph "Configuration opions".

Adds options for the interface's reservation. Interfaces reservations are required for specific settings for the client no matter from what scope the client is getting its IP-address lease. Interface reservation has two differences from scope reservation. At first, does not define a fixed IP-address for the client. Thus it takes for the server to dynamically define from which scope and which IP-address is to be given to the client. Secondly, allows to change client’s class. If "Class ID" option is defined for the interfaces reservation, the class will be changed for the option’s value when a client from this reservation sends a request. It becomes necessary when DHCP client does not send its class.

Creating interface reservation does not contradict with scope reservation for the same client.

• • "INTERFACE" –  name of the interface where client’s (CLIENT_ID) reservation is created. If this interface did not have a reservation for this client, this command will automatically create this reservation and will add it the options set.
  • "CLIENT_ID" – reservation client identifier. If this option with the same name was defined, the value will be changed to the one specified in this command.
  • "OPTION_NAME" and "OPTION_VALUE" – the description of these parameters is in paragraph "Configuration opions".

Allows to control options which were requested by the client and given to it. On the map divisions (option sets) are displayed using the following indication:

• "SR" – scope reservation division;
• "IR" – interface reservation division;
• "S" – scope reservation;
• "I" – client’s interface division;
• "SV" – server’s division.

If a requested option was not defined in any of server’s divisions, it is displayed as <not supplied> in the list. Moreover, the options which were requested by clients and supplied to them but which were not defined in any division (e.g. Subnet Mask) are marked as "DF".

• "INTERFACE" – name of a network interface which information is requested. Instead of interface name can be specified "*", this will print information for all interfaces.

• "CLIENT_ID" – client’s identifier, which information is requested. Instead of client’s identifier it is permitted to specify "*", this will print information about all clients for the specified interface. The information is shown only for clients with given address lease from one of the scopes which is attached to the specified interface.

Displays the IP-addresses canceled leases database.

• "INTERFACE" – name of a network interface which information is requested. Instead of interface name can be specified "*", this will print information for all interfaces.

Virtual interfaces

Creates virtual interface.

After their start, DHCP clients send broadcast request in order to get an IP-address lease. As a client at this time does not yet have an IP-address the server also uses broadcast packets to communicate with a client. It is known that broadcast packets are not routed and, thus, the dialog between DHCP server and DHCP client can occur only within one network (physical network). If DHCP server is connected to another network, the direct dialog cannot take place. However, the router which logically connects two networks with DHCP client and DHCP server can have a special software running – DHCP Relay Agent (DRA). DRA retranslates DHCP packets (including broadcast packets) from DHCP clients to DHCP server and back. Data exchange between DRA and DHCP server is performed using unicast packets only. Thus, DRA and DHCP must know each other’s IP-addresses starting from their configuration stage. For this purpose DHCP server has virtual interfaces. In fact DHCP server virtual interface is a physical network interface placed in DRA. As DHCP server does not know this interface's subnets sets, these subnets should be specified while virtual interfaces configuration.

• "VIFNAME" – name of the DHCP server’s virtual interface.
• "GATEWAY" – IP-address of DRA which has a corresponding physical interface.
• "GWIFNAME" – name of DRA’s interface that performs retranslation of DHCP packets to DHCP clients. If the "*" symbol is used as "GWIFNAME" parameter DRA is allowed to use all its interfaces to retranslate DHCP packets.

virtual interface <VIFNAME> change <GATEWAY> <GWIFNAME|*>

Changes settings of virtual interface.

• "VIFNAME" – name of the DHCP server’s virtual interface.
• "GATEWAY" – new IP-address of DRA.
• "GWIFNAME" – new name of DRA’s interface.

In server’s configuration we now can observe the virtual interface. Working with this interface is no different from other interfaces. However, before a scope is attached to it, a set of subnets should be configured.

• "VIFNAME" – name of the DHCP server’s virtual interface.
• "IP_ADDRESS" – IP-address which DRA has for this subnet.
• "SUBNET_MASK" – subnet mask.

delete virtual interface <VIFNAME>

General parameters

Shows the list of all options DHCP server can include in messages for clients.

Shows version of DHCP server in XML format.

useroption <NAME> code <CODE> type <TYPE>

Besides standard DHCP Server options user can create his own.

• "NAME" – name of option.
• "CODE" – the code of the created option should be unique from the standard and previously created user-defined DHCP options.
• "TYPE" – the type of the option can be of the following values:
  • "n8" – 8-bit integer.
  • "n16" – 16-bytes integer.
  • "n32" – 32-bytes integer.
  • "ip" – IP-address.
  • "text" – text string (254 characters maximum)
  • "ipp" – IP-address pairs (classful routes).
  • "clr" – classless routes in the following format: A.B.C.D/M>R.R.R.R:
    • "A.B.C.D" – network address,
    • "M" – network mask,
    • "R.R.R.R" – gateway IP-address.

Displays the list of unleased IP-addresses. Clients to which DHCP server failed to give an IP-address for a lease are put to a special list – unleases. The records in this list are saved for 15 minutes if a client does not repeat an attempt to get a lease. Each record in the list consists of the following fields:

• Name of a network interface from which a client’s request for a lease was received.
• Client’s identifier
• Client’s class identifier
• Host name

• "SUBSTR" – a substring for a partial list view. When executing a command the server will print only those records which fields contain the substring (one of the fields). Substring is case-sensitive. If "*" is specified as a substring the full list is printed.