ISC DHCPv4 Option Configuration
DHCP option values can be defined on a global or scoped basis to influence the configuration parameters of devices initializing via DHCP. Within the relevant scope the option is declared using the following general syntax which is equivalent to that for DHCP for IPv4:
option option-name option-value;
where:
- option is the keyword indicating that an option is specified on this line.
- option-name is the name of the option according to the server
- option-value is the actual value of the option to provide to the client.
The following table summarizes the DHCP options currently supported along with the corresponding ISC DHCP option-name and option-value data type. The Tag and Name columns in the table provide a cross reference to the Internet standard option definitions.
| Tag | Name | option-name | option-value type |
|---|---|---|---|
| 1 | Subnet Mask | subnet-mask | IP address formatted mask |
| 2 | Time Offset | time-offset | integer - seconds offset from UTC |
| 3 | Router (Default Gateway) | routers | IP address(es) in preferred order |
| 4 | Time Server | time-servers | IP address(es) in preferred order |
| 5 | Name Server | ien116-name-servers | IP address(es) of IEN 116 name server(s) in preferred order |
| 6 | Domain Server | domain-name-servers | IP address(es) in preferred order |
| 7 | Log Server | log-servers | IP address(es) in preferred order |
| 8 | Quotes Server | cookie-servers | IP address(es) in preferred order |
| 9 | LPR Server | lpr-servers | IP address(es) in preferred order |
| 10 | Impress Server | impress-servers | IP address(es) in preferred order |
| 11 | RLP Server | resource-location-servers | IP address(es) in preferred order |
| 12 | Hostname | host-name | text string |
| 13 | Boot File Size | boot-size | integer |
| 14 | Merit Dump File | merit-dump | text (filename) |
| 15 | Domain Name | domain-name | text - client's domain name of the client |
| 16 | Swap Server | swap-server | IP address |
| 17 | Root Path | root-path | text (directory path) |
| 18 | Extension File | extensions-path | text (filename) |
| 19 | Forward On/Off | ip-forwarding | * true = enable IP forwarding * false = disable |
| 20 | Source Routing | non-local-source-routing | * true = enable forwarding of datagrams with non-local source routing * false = disable |
| 21 | Policy Filter | policy-filter | IP address pair(s) consisting of destination and corresponding mask for filtering of source-routed datagrams separated by a space; multiple pairs are comma separated. |
| 22 | Max Datagram Size for Reassembly | max-dgram-reassembly | integer (minimum = 576) |
| 23 | Default IP TTL | default-ip-ttl | integer |
| 24 | MTU Timeout | path-mtu-aging-timeout | integer (seconds) |
| 25 | MTU Plateau | path-mtu-plateau-table | integer(s) - (68 is the minimum value of each) |
| 26 | MTU Interface | interface-mtu | MTU for a given interface (68 is the minimum value) |
| 27 | MTU Subnet | all-subnets-local | true or false |
| 28 | Broadcast Address | broadcast-address | IP address |
| 29 | Mask Discovery | perform-mask-discovery | * true = client should perform subnet mask discovery using ICMP * false = client should not do so |
| 30 | Mask Supplier | mask-supplier | *true = client should respond to ICMP subnet mask requests * false = client shouldn't respond |
| 31 | Router Discovery | router-discovery | * true = client should perform router discovery per RFC 1256 *false = client should not perform router discovery |
| 32 | Router Request | router-solicitation-address | IP address |
| 33 | Static Route | static-routes | IP address pair(s): destination address and corresponding router separated by space; multiple pairs comma separated; use routers option (3) to specify a default route |
| 34 | Trailers | trailer-encapsulation | * true = use trailers (RFC 893) when using ARP * false = do not use trailers |
| 35 | ARP Timeout | arp-cache-timeout | integer (seconds) |
| 36 | Ethernet | ieee802-3-encapsulation | * true = 802.3 encapsulation * false = Ethernet2 (RFC 894) |
| 37 | Default TCP TTL | default-tcp-ttl | integer (seconds) |
| 38 | Keepalive Time | tcp-keepalive-interval | integer (seconds) |
| 39 | Keepalive Data | tcp-keepalive-garbage | * true = send a garbage octet with keepalive messages for backward TCP compatibility * false = do not send garbage octet |
| 40 | NIS Domain | nis-domain | text |
| 41 | NIS Servers | nis-servers | IP address(es) in preferred order |
| 42 | NTP Servers | ntp-servers | IP address(es) in preferred order |
| 43 | Vendor Specific | vendor-encapsulated-options | string of vendor-specific information |
| 44 | NETBIOS Name Server | netbios-name-servers | IP address(es) in preferred order |
| 45 | NETBIOS Dist Server | netbios-dd-server | IP address(es) in preferred order |
| 46 | NETBIOS Node Type | netbios-node-type | integer encoding of node type:1 = B-node - broadcast no WINS 2 = P-node - WINS only 4 = M-node - broadcast then WINS 8 = H-node - WINS then broadcast |
| 47 | NETBIOS Scope | netbios-scope | string encoded in accordance with RFCs 1001-1002 |
| 48 | X Window Font | font-servers | IP address(es) in preferred order |
| 49 | X Window Manager | x-display-manager | IP address(es) in preferred order |
| 50 | Address Request | dhcp-requested-address | N/A - used by the client to request a particular IP address |
| 51 | Address Time | dhcp-lease-time | N/A - used by client to request a lease time (this option is not configurable on the ISC DHCP server - config file parameters max-lease-time and default-lease-time are used) |
| 52 | Overload | dhcp-option-overload | integer indicating which DHCP header field(s) hold options:1 = file field 2 = sname field 3 = both file and sname fields |
| 53 | DHCP Message Type | dhcp-message-type | N/A used to identify message type1 = DHCPDISCOVER 2 = DHCPOFFER 3 = DHCPREQUEST 4 = DHCPDECLINE 5 = DHCPACK 6 = DHCPNAK 7 = DHCPRELEASE 8 = DHCPINFORM 9 = DHCPFORCERENEW 10=DHCPLEASEQUERY 11=DHCPLEASEUNASIGNED 12=DHCPLEASEUNKNOWN 13=DHCPLEASEACTIVE |
| 54 | DHCP Server Identifier | dhcp-server-identifier | N/A - server-identifier parameter in the config file is used instead |
| 55 | Parameter List | dhcp-parameter-request-list | integer(s) denoting options to provide to the client |
| 56 | DHCP Message | dhcp-message | N/A - used to populate an error message from the server with a DHCPNAK or from a client in a DHCPDECLINE message |
| 57 | DHCP Max Msg Size | dhcp-max-message-size | integer - used as a default if not provided by the client |
| 58 | Renewal Time | dhcp-renewal-time | N/A - based on the lease time |
| 59 | Rebinding Time | dhcp-rebinding-time | N/A - based on the lease time |
| 60 | Vendor Class Id | vendor-class-identifier | string |
| 61 | Client Id | dhcp-client-identifier | text (string or hex digits) - be aware that some clients prepend a 0 to the ASCII text so you may have to encode "\\ 0foo" instead of just foo |
| 62 | Netware/IP Domain | nwip-domain | string |
| 63 | Netware/IP Options - specify as single hex string or per suboption | nwip-suboptionsnwip.nsq-broadcast nwip.preferred-dss nwip.nearest-nwip-server nwip.autoretries nwip.autoretry-secs nwip.nwip-1-1 nwip.primary-dss | string of all options in hexflag IP address(es) IP address(es) integer integer integer IP address |
| 64 | NIS+ Domain Name | nisplus-domain | text (domain name) |
| 65 | NIS+ Server Address | nisplus-servers | IP address(es) in preferred order |
| 66 | Server Name | tftp-server-name | text (server domain name) |
| 67 | Bootfile Name | bootfile-name | text (file name) |
| 68 | Home Agent Addresses | mobile-ip-home-agent | IP address(es) in preferred order |
| 69 | SMTP Server | smtp-server | IP address(es) in preferred order |
| 70 | POP3 Server | pop-server | IP address(es) in preferred order |
| 71 | NNTP Server | nntp-server | IP address(es) in preferred order |
| 72 | WWW Server | www-server | IP address(es) in preferred order |
| 73 | Finger Server | finger-server | IP address(es) in preferred order |
| 74 | IRC Server | irc-server | IP address(es) in preferred order |
| 75 | StreetTalk Server | streettalk-server | IP address(es) in preferred order |
| 76 | StreetTalk Directory Assistance (STDA) Server | streettalk-directory- assistance-server | IP address(es) |
| 77 | User Class | user-class | string |
| 78 | Service Location Protocol (SLP) Directory Agent | slp-directory-agent | Two parameters (space separated): * Boolean - true = use only addresses provided in this option; false = use provided options and others via SLP agent discovery * IP address(es) of SLP directory agent(s) |
| 79 | SLP Service Scope | slp-service-scope | Two parameters (space separated): * Boolean - true = use only service scope(s) provided in this option; false = use provided scope(s) and others statically configured * text string(s) of service scope(es) |
| 80 | Rapid Commit | N/A - sent by client to request 2 packettransaction instead of the normal 4 packet transaction | |
| 81 | Client FQDN | fqdn option space | N/A - sent by client regarding DDNS update. Please refer to the Client FQDN Option page for server parameters associated with this option |
| 82 | Relay Agent Information | agent.circuit-id agent.remote-id agent.DOCSIS-device-class agent.link-selection | N/A for setting values. Please refer to the Relay Agent Information Options page for more details. |
| 83 | iSNS | Not natively supported | N/A |
| 85 | NDS Servers | nds-servers | IP address(es) |
| 86 | NDS Tree Name | nds-tree-name | string |
| 87 | NDS Context | nds-context | string |
| 88 | BCMCS Controller Domain Name | bcms-controller-names | domain list |
| 89 | BCMCS Controller IPv4 address option | bcms-controller-address | IP address list |
| 90 | Authentication | N/A - used to pass DHCP authentication information | |
| 91 | Client-last-transaction- time option | N/A - used as part of DHCP Lease Query | |
| 92 | Associated-ip option | N/A - used as part of DHCP Lease Query | |
| 93 | Client System | N/A - used by PXE clients to convey the client hardware architecture to the server | |
| 94 | Client NDI | N/A - used by PXE clients to convey the client's network interface type to the server | |
| 95 | LDAP | Not natively supported | N/A |
| 97 | UUID/GUID | N/A - used by PXE clients to convey the client's unique identifier to the server | |
| 98 | User Authentication Servers | uap-servers | text (URL list) |
| 99 | GEOCONF_ CIVIC | Not natively supported | N/A |
| 112 | Netinfo Address | netinfo-server-address | IP address(es) - not defined in any RFC but assigned by IANA |
| 113 | Netinfo Tag | netinfo-server-tag | test string - - not defined in any RFC but assigned by IANA |
| 114 | Default URL | default-url | text (URL) - not defined in any RFC but assigned by IANA |
| 116 | Auto-Config | N/A - used by clients to request auto-configuration support from the server | |
| 117 | Name Service Search | Not natively supported | N/A |
| 118 | Subnet Selection Option | subnet-selection | N/A - client preferred subnet for address assignment |
| 119 | Domain Search | domain-search | One or more domain names each enclosed in quotes and separated by commas |
| 120 | SIP Servers DHCP Option | Not natively supported | N/A |
| 121 | Classless Static Route Option | Not natively supported | N/A |
| 122 | CCC | Not natively supported | N/A |
| 123 | GeoConf Option | Not natively supported | N/A |
| 124 | Vendor Identified Vendor Class | N/A - sent by client to convey its vendor-identified vendor class | |
| 125 | Vendor Identified Vendor- Specific Information | vivso | string |