Reference: DHCPv4 client options - BlueCat Address Manager - 9.1.0

Address Manager Administration Guide

prodname
BlueCat Address Manager
version_custom
9.1.0

This section describes DHCPv4 client options that can be configured in Address Manager.

These are the DHCPv4 client options that you can add to a DHCPv4 configuration and deploy to DHCP servers. These options relate to extra settings for clients. For more information about these options, see RFCs 2132, 2242, 2610, 2241, and 2485.

Readers are also encouraged to examine RFCs 1497 and 1122 for further background information. Options that accept Boolean values are activated by a value of 1 unless otherwise specified. When specifying a list of IPv4 addresses, the first address entered takes precedence.

IP Layer parameters per host

The following DHCPv4 client option codes specify values that apply to the entire client (host) system, and do not necessarily just apply to a single interface.
DHCP Option Description
Time Offset (2) Specifies the time offset from GMT (Greenwich Mean Time) for the DHCP client. This offset is expressed in seconds, with a negative value representing locations west of Greenwich. Thus EST, which is 5 hours behind Greenwich Mean Time, could be expressed as -18000.
Router (3) Indicates the default router for this configuration. In Windows DHCP, this option is known as Default Gateway. The data consists of one or more IP addresses.
Time Server (4 ) Indicates RFC 868 time servers that are available to a client. The data consists of one or more IP addresses.
IEN Name Server (5) Specifies IEN name servers. These are not the same as BIND name servers.
DNS Server (6 ) Specifies one or more DNS servers that the client contacts for DNS resolution. These are comparable to the Windows primary and secondary DNS servers that are configured for clients.
Log Server (7) Specifies a log server for the client to use. This is an MIT-LCS UDP log server, and is identified with on or more IPv4 addresses, with the first address taking precedence.
Cookie Server (8) Refers to “Quote of the Day” servers as described in RFC 865. They are specified with IPv4 addresses.
LPR Server (9) Lists line printer servers as defined in RFC 1179. They are defined using a list of IPv4 addresses and are matched in the order specified.
Impress Server (10) Lists Imagen Impress servers. They are defined using a list of IPv4 addresses and are matched in the order specified.
Resource Location Server (11) Lists resource location server addresses for the client to use on the local network as specified in RFC 887. They are defined using a list of IPv4 addresses and are matched in the order specified.
Host Name (12 ) Specifies a host name for the client. This may or may not be qualified with the local domain name.
Boot Size (13) Describes the size of the boot file image for the client. The size is expressed as a number of 512-byte segments.
Merit Dump File (14) Provides the complete path and file name of the server to which the client dumps its core image in the event that the client crashes.
Domain Name (15) Specifies the domain name for the client system.
Swap Server (16) Specifies a swap server for the client.
Root Path (17) Specifies the path as a text value. A root disk contains essential startup files for client systems in several schemes, including NFS.
Extensions Path (18) Specifies the path to a file as a text value. The file contains options or vendor-specific configuration settings to be used in DHCP device configuration.
IP Forwarding (19) A Boolean value indicating whether a client with more than one network interface should forward packets between its interfaces.
Non-Local Source Routing (20) A Boolean value indicating whether a client should forward packets from a non-local source.
Policy Filter Masks (21) Lists one or more addresses and submasks used with IP forwarding. If this option is specified, a forwarded packet goes to one of these addresses as its next hop or else the packet is dropped.
Max Datagram Reassembly (22) Specifies the maximum size of datagrams that the client should be prepared to reassemble, specified as an unsigned 16-bit integer value. This minimum legal value is 576.
Default IP TTL (23) Specifies the time to live (TTL) value that clients should specify for outgoing packets. This is expressed as an unsigned 16-bit integer with a value between 1 and 255.
Path MTU Aging Timeout (24) Specifies the aging timeout for Path Maximum Transfer Unit (PMTU) values in seconds as an unsigned 32-bit integer. For more information about PMTU, see option 25 (below), the PMTU Plateau Table or RFC 1191.
Path MTU Plateau Table (25) Specifies the PMTU Plateau Table. It is a list of Maximum Transfer Unit sizes for an arbitrary number of paths. These values are stored as unsigned 16-bit integers and are subject to a TTL. The mechanism for this operation is described in RFC 1191.

Interface-specific options

The following DHCPv4 client option codes apply to a specific interface. Therefore, it is possible for a client-device containing multiple interfaces to have different option values per interface.
DHCP Option Description
Interface MTU (26) Specifies the Maximum Transfer Unit (MTU) size for packets being sent from a specific interface. This is specified as an unsigned 16-bit integer value.
All Subnets Local (27) Indicates whether all local subnets have the same MTU as the network to which the client is attached. This is specified using a Boolean value.
Broadcast Address (28) Specifies a particular broadcast address for a subnet. This is specified using an IPv4 address value.
Perform Mask Discovery (29) A Boolean value indicating whether an ICMP address mask request message is sent to the gateway to receive a subnet mask. This process is explained in RFC 950.
Mask Supplier (30) A Boolean value indicating whether or not a client responds to subnet mask requests using ICMP. This process is explained in RFC 950.
Router Discovery (31) A Boolean value indicating whether the client performs Router Discovery as explained in RFC 1256. A specific router can be specified with DHCP Option 32.
Router Solicitation Address (32) An address used in conjunction with DHCP Option 31 specifying a particular router address with an IPv4 address. This address is used by the client when submitting router discovery messages in accordance with RFC 1256.
Static Routes (33) Lists static routes for the client to store in its routing cache. The first address specified is the destination address; the second address is the router for that address. The route 0.0.0.0 is an illegal entry for this option.

Link Layer interface-specific options

The following DHCPv4 client option codes apply to a specific interface. They deal with the link layer of the interface rather than the IP layer.
DHCP Option Description
Trailer Encapsulation (34) A Boolean value indicating whether the client should negotiate the use of ARP Trailers in accordance with RFC 893.
ARP Cache Timeout (35) Specifies the timeout for ARP cache entries in seconds, specified as an unsigned 32-bit integer value.
IEEE 802.3 Encapsulation (36) A Boolean value indicating the type of encapsulation used for Ethernet interfaces. A value of false indicates Ethernet 2 encapsulation (RFC 894) and a value of true indicates IEEE 802.3 (RFC 1042).

TCP interface-specific options

The following DHCPv4 client option codes in this section apply to Transport Control Protocol (TCP) settings on a per-interface basis.
DHCP Option Description
Default TCP TTL (37) Specifies the default TTL value that client systems uses for the TCP segments that they send out. It is specified with an unsigned 8-bit integer representing the number of seconds.
TCP Keep Interval (38) Specifies the number of seconds that the client waits before sending a TCP keepalive message, specified with an unsigned 32-bit integer. A value of 0 prevents the client TCP from sending keepalive messages.
TCP Keep Alive Garbage (39) A Boolean value used in conjunction with DHCP Option 38. It indicates whether a client should send keepalive messages with an octet of garbage to comply with older TCP implementations.

Application and service options

The following DHCPv4 client option codes are provided to specify client settings for particular clients and services.
DHCP Option Description
NIS Domain (40) Defines the clients NIS domain using the ASCII character set.
NIS Server (41) Lists NIS servers, specified using IPv4 addresses in the order of preference.
NTP Server (42) Lists NTP servers, specified using IPv4 addresses in order of preference.
Vendor Encapsulated Options (43) Contains vendor-specific information or options for devices, specified as a hexadecimal string. The value must start with 1 or 2 hexadecimal digits, with subsequence digits separated with colons. For example:
  • Single-digit values: A:B:0:1:2:3
  • Two-digit values: AA:BB:00:01:02:03
WINS/NBNS Server (44) Lists WINS/NBNS servers (RFC 1001/1002), specified using IPv4 addresses in order of preference.
NetBIOS over TCP/IP NBDD (45) Lists NetBIOS Datagram Distribution servers (RFC 1001/1002) specified using IPv4 addresses in order of preference.
WINS/NBT Node Type (46) Specifies the type of NetBIOS node for the client, specified as an 8-bit integer value:1—B-node2—P-node4—M-node8—H-node
NetBIOS Scope ID (47) Specifies the NetBIOS Scope ID for a client.
X-Window Font Server (48) Lists X-Window Font servers (RFC 1198), specified using IPv4 addresses in order of preference.
X-Window Display Manager (49) Lists X-Window Display Manager servers (RFC 1198) available to the client, specified using IPv4 addresses in order of preference.
Netware/IP Domain (62) Specifies the NetWare/IP domain name for the client.
Netware/IP - NSQ broadcast (63.5) A Boolean value indicating whether or not the client should perform a NetWare nearest server query to locate the nearest NetWare/IP server.
Netware/IP - Preferred DSS (63.6) Lists NetWare domain SAP/RIP servers (DSS), specified using IPv4 addresses in order of preference.
Netware/IP - Nearest NWIP Server (63.7) Lists the nearest NetWare/IP servers, specified using IPv4 addresses in order of preference.
Netware/IP - Auto Retries (63.8) Identifies the number of times a client attempts to communicate with a DSS server upon startup, specified using an unsigned 8-bit integer value.
Netware/IP - Auto Retry Delay (63.9) Indicates the number of seconds that a client should wait between attempts to contact a NetWare domain SAP/RIP server (DSS) at startup, specified as an unsigned 8-bit integer value.
Netware/IP - 1.1 Compatibility (63.10) A Boolean value indicating whether a client supports connectivity to NetWare/IP version 1.1 servers.
Netware/IP - Primary DSS (63.11) Identifies the primary NetWare domain SAP/RIP server (DSS) for the NetWare/IP domain to which the client belongs, specified as an IPv4 address.
NIS+ Domain Name (64) Identifies the name of the NIS+ domain to which the client belongs.
NIS+ Server (65) Lists NIS+ servers, specified using IPv4 addresses in order of preference.
TFTP Server Name (66) Identifies the name of a TFTP server.
Boot File Name (67) Identifies the name of the boot file for this client.
Mobile IP Home Agent (68) Lists mobile IP home agents available to the client, specified using IPv4 addresses in order of preference.
SMTP Server (69) Lists Simple Mail Transport Protocol (SMTP) servers available to the client, specified using IPv4 addresses in order of preference.
POP3 Server (70) Lists POP servers available to the client, specified using IPv4 addresses in order of preference.
NNTP Server (71) Lists Network News Transport Protocol (NNTP) servers available to the client, specified using IPv4 addresses in order of preference.
WWW Server (72) Lists World Wide Web (WWW) servers available to the client, specified using IPv4 addresses in order of preference.
Finger Server (73) Lists Finger servers available to the client, specified using IPv4 addresses in order of preference.
IRC Server (74) Lists IRC servers available to the client, specified using IPv4 addresses in order of preference.
Street Talk Server (75) Lists Street Talk servers available to the client, specified using IPv4 addresses in order of preference.
Street Talk Directory Assistance Server (76) Lists StreetTalk Directory Assistance servers available to the client, specified using IPv4 addresses in order of preference.
SLP Directory Agent (78) Lists SLP Directory Agents available to the client, specified using IPv4 addresses in order of preference (as defined in RFC 2610). If the check box is selected, the client must not use either active or passive multicast discovery of directory agents. This option also requires the use of DHCP Option 79, SLP Service Scope.
SLP Service Scope (79) Lists SLP scopes that a client is configured to use. If the check box is selected, the client’s static SLP Service Scope settings are overridden by the settings specified by this option.
NDS Server (85) Lists Novell Directory Services (NDS) servers available to the client, specified using IPv4 addresses in order of preference.
NDS Tree Name (86) Specifies the name of the NDS tree that the client contacts. This is a UTF-8 string with a limit of 255 characters and cannot be zero terminated.
NDS Context (87) Describes the NDS context for the client. This field has a maximum length of 255 bytes. If the NDS Context string is longer than this, it must be split over multiple instances of this option. This is a limitation of the DHCP options specification (RFC 2131/2132).
UAP Server (98) Contains a list of servers that support user authentication protocol for the client. These are specified with URL notation. They can be HTTP or HTTPS URLs specified in ASCII with space character delimitation. Port numbers can be specified to override the default ports (80, 443).
Name Service Search (117) Specifies the order in which different types of naming services should be consulted on a network (as described in RFC 2937). The numbers are listed by preference and the client uses the naming services based on this list:6—DNS server option41—NIS Option 44—WINS/NetBIOS option 65—NIS+ server option 0—Local Naming Information (such as /etc/hosts )
Domain Search (119) Specifies the domain search list used when resolving hostnames with DNS as defined in RFC 3397.
SIP Servers (120) Enable a client to locate a SIP server for VoIP use (as defined in RFC 3361). You can choose whether a field for address or text entry appears based on the option selected.
Classless Static Route (121) Updates a client’s routing table when DHCP messages are exchanged. The fields for address, mask, and router are used to define routes, and Move up/Move down are used to sort routes by precedence. Clicking Remove removes routes from this list.
Cablelabs Client Configuration Option (122) Configures cable modems and media terminal adapters according to the PacketCable security standard. More information can be found in this standard, or in RFC 3495.
TSP’s Primary DHCP Server Address (122.1) The IPv4 address for the primary DHCP server from which this client is allowed to accept DHCP offer messages.
TSP’s Secondary DHCP Server Address (122.2) The IPv4 address for the secondary DHCP server from which this client is allowed to accept DHCP offer messages.
TSP’s Provisioning Server Address (122.3) The address or FQDN for the provisioning server that this modem or MTA contacts.
TSP’s AS-REQ/AS-REP Backoff and Retry (122.4) Requests to the Kerberos Authentication Server or the Ticket Granting Server are managed by the values in this option.
  • The Minimum Timeout value specifies the minimum expiry time that tickets should be requested in seconds, according to policy at this site.
  • The Maximum Timeout value specifies the maximum expiry time that tickets should be requested in seconds, according to policy at this site.
  • The Retry Count value specifies the number of retries that should be attempted before the request is aborted. Each field accepts values between 0 and 4,294,967,295.
TSP’s AP-REQ/AP-REP Backoff and Retry (122.5) Controls the timeout and retry values for Kerberos authentication headers.
  • The Minimum Timeout value specifies the minimum expiry time that tickets should be requested in seconds, according to policy at this site.
  • The Maximum Timeout value specifies the maximum expiry time that tickets should be requested in seconds, according to policy at this site.
  • The Retry Count value specifies the number of retries that should be attempted before the request is aborted. Each field accepts values between 0 and 4,294,967,295.
TSP’s Kerberos Realm Name (122.6) Lists the Kerberos realm that should be used to authenticate against. Realm names are always specified in capitals and this instance must be specified in domain style as described in RFC 1510.
TSP’s Ticket Granting Server Utilization (122.7) Select this check box if the option should use a Ticket Granting Ticket when obtaining service from a PacketCable application server.
TSP’s Provisioning Timer Value (122.8) Defines the timeout in seconds that the provisioning process has to complete, specified as an integer value between 0 and 255.
TFTP Server Address (150) Specifies the IPv4 address for the TFTP server that the client uses. Some devices, such as certain Voice over Internet Protocol (VoIP) phones, download their initial configuration from a TFTP server.
IP Telephone (176) This option is used to inform Avaya phones of several parameters around the host network using string values. Typically, several copies of this option pass the various required strings to the Avaya phones. Implementors of this option should check the Avaya Administrator’s Guide for their phone system to obtain the appropriate values for this option.
WPAD URL (252) This options provides the URL for a WPAD (Web Proxy Autodiscovery Protocol) configuration file. Specify the URL for the configuration file in the Text field.