BOOTP and DHCP options
 |
Description | Glossary | RFCs | Publications | Obsolete RFCs |
Description:
| Base protocols: | BOOTP, Bootstrap Protocol. DHCP, Dynamic Host Configuration Protocol. |
| Links: | IANA: BOOTP and DHCP options. |
DHCP options have the same format as the BOOTP ‘vendor extensions’. Options may be fixed length or variable length. All options begin with a tag byte, which uniquely identifies the option. Fixed length options without data consist of only a tag byte. The value of the length byte does not include the tag and length fields.
Options containing NVT ASCII data SHOULD NOT include a trailing NULL. The receiver of such options MUST be prepared to delete trailing NULLs if they exist. The receiver MUST NOT require that a trailing NULL be included in the data. In the case of some variable length options, the length field is a constant but must still be specified.
| Code | Data length | Description | References |
|---|---|---|---|
| 0 | 0 | Pad. | RFC 2132 |
| 1 | 4 | Subnet Mask. | RFC 2132 |
| 2 | 4 | Time Offset (deprecated). | RFC 2132 |
| 3 | 4+ | Router. | RFC 2132 |
| 4 | 4+ | Time Server. | RFC 2132 |
| 5 | 4+ | Name Server. | RFC 2132 |
| 6 | 4+ | Domain Name Server. | RFC 2132 |
| 7 | 4+ | Log Server. | RFC 2132 |
| 8 | 4+ | Quote Server. | RFC 2132 |
| 9 | 4+ | LPR Server. | RFC 2132 |
| 10 | 4+ | Impress Server. | RFC 2132 |
| 11 | 4+ | Resource Location Server. | RFC 2132 |
| 12 | 1+ | Host Name. | RFC 2132 |
| 13 | 2 | Boot File Size. | RFC 2132 |
| 14 | 1+ | Merit Dump File. | RFC 2132 |
| 15 | 1+ | Domain Name. | RFC 2132 |
| 16 | 4 | Swap Server. | RFC 2132 |
| 17 | 1+ | Root Path. | RFC 2132 |
| 18 | 1+ | Extensions Path. | RFC 2132 |
| 19 | 1 | IP Forwarding enable/disable. | RFC 2132 |
| 20 | 1 | Non-local Source Routing enable/disable. | RFC 2132 |
| 21 | 8+ | Policy Filter. | RFC 2132 |
| 22 | 2 | Maximum Datagram Reassembly Size. | RFC 2132 |
| 23 | 1 | Default IP Time-to-live. | RFC 2132 |
| 24 | 4 | Path MTU Aging Timeout. | RFC 2132 |
| 25 | 2+ | Path MTU Plateau Table. | RFC 2132 |
| 26 | 2 | Interface MTU. | RFC 2132 |
| 27 | 1 | All Subnets are Local. | RFC 2132 |
| 28 | 4 | Broadcast Address. | RFC 2132 |
| 29 | 1 | Perform Mask Discovery. | RFC 2132 |
| 30 | 1 | Mask supplier. | RFC 2132 |
| 31 | 1 | Perform router discovery. | RFC 2132 |
| 32 | 4 | Router solicitation address. | RFC 2132 |
| 33 | 8+ | Static routing table. | RFC 2132 |
| 34 | 1 | Trailer encapsulation. | RFC 2132 |
| 35 | 4 | ARP cache timeout. | RFC 2132 |
| 36 | 1 | Ethernet encapsulation. | RFC 2132 |
| 37 | 1 | Default TCP TTL. | RFC 2132 |
| 38 | 4 | TCP keepalive interval. | RFC 2132 |
| 39 | 1 | TCP keepalive garbage. | RFC 2132 |
| 40 | 1+ | Network Information Service Domain. | RFC 2132 |
| 41 | 4+ | Network Information Servers. | RFC 2132 |
| 42 | 4+ | NTP servers. | RFC 2132 |
| 43 | 1+ | Vendor specific information. | RFC 1533, RFC 2132 |
| 44 | 4+ | NetBIOS over TCP/IP name server. | RFC 1533, RFC 2132 |
| 45 | 4+ | NetBIOS over TCP/IP Datagram Distribution Server. | RFC 1533, RFC 2132 |
| 46 | 1 | NetBIOS over TCP/IP Node Type. | RFC 1533, RFC 2132 |
| 47 | 1+ | NetBIOS over TCP/IP Scope. | RFC 1533, RFC 2132 |
| 48 | 4+ | X Window System Font Server. | RFC 1533, RFC 2132 |
| 49 | 4+ | X Window System Display Manager. | RFC 1533, RFC 2132 |
| 50 | 4 | Requested IP Address. | RFC 1533, RFC 2132 |
| 51 | 4 | IP address lease time. | RFC 1533, RFC 2132 |
| 52 | 1 | Option overload. | RFC 1533, RFC 2132 |
| 53 | 1 | DHCP message type. | RFC 1533, RFC 2132, RFC 3203, RFC 4388 |
| 54 | 4 | Server identifier. | RFC 1533, RFC 2132 |
| 55 | 1+ | Parameter request list. | RFC 1533, RFC 2132 |
| 56 | 1+ | Message. | RFC 1533, RFC 2132 |
| 57 | 2 | Maximum DHCP message size. | RFC 1533, RFC 2132 |
| 58 | 4 | Renew time value. | RFC 1533, RFC 2132 |
| 59 | 4 | Rebinding time value. | RFC 1533, RFC 2132 |
| 60 | 1+ | Class-identifier. | RFC 1533, RFC 2132 |
| 61 | 2+ | Client-identifier. | RFC 1533, RFC 2132, RFC 4361 |
| 62 | 1 to 255 | NetWare/IP Domain Name. | RFC 2242 |
| 63 | NetWare/IP information. | RFC 2242 | |
| 64 | 1+ | Network Information Service+ Domain. | RFC 2132 |
| 65 | 4+ | Network Information Service+ Servers. | RFC 2132 |
| 66 | 1+ | TFTP server name. | RFC 2132 |
| 67 | 1+ | Bootfile name. | RFC 2132 |
| 68 | 0+ | Mobile IP Home Agent. | RFC 2132 |
| 69 | 4+ | Simple Mail Transport Protocol Server. | RFC 2132 |
| 70 | 4+ | Post Office Protocol Server. | RFC 2132 |
| 71 | 4+ | Network News Transport Protocol Server. | RFC 2132 |
| 72 | 4+ | Default World Wide Web Server. | RFC 2132 |
| 73 | 4+ | Default Finger Server. | RFC 2132 |
| 74 | 4+ | Default Internet Relay Chat Server. | RFC 2132 |
| 75 | 4+ | StreetTalk Server. | RFC 2132 |
| 76 | 4+ | StreetTalk Directory Assistance Server. | RFC 2132 |
| 77 | Variable. | User Class Information. | RFC 3004 |
| 78 | Variable. | SLP Directory Agent. | RFC 2610 |
| 79 | Variable. | SLP Service Scope. | RFC 2610 |
| 80 | 0 | Rapid Commit. | RFC 4039 |
| 81 | 4+. | FQDN, Fully Qualified Domain Name. | RFC 4702 |
| 82 | Variable. | Relay Agent Information. | RFC 3046, RFC 5010 |
| 83 | 14+ | Internet Storage Name Service. | RFC 4174 |
| 84 | RFC 3679 | ||
| 85 | Variable. | NDS servers. | RFC 2241 |
| 86 | Variable. | NDS tree name. | RFC 2241 |
| 87 | Variable. | NDS context. | RFC 2241 |
| 88 | Variable. | BCMCS Controller Domain Name list. | RFC 4280 |
| 89 | 4+ | BCMCS Controller IPv4 address list. | RFC 4280 |
| 90 | Variable. | Authentication. | RFC 3118 |
| 91 | 4 | client-last-transaction-time. | RFC 4388 |
| 92 | 4n | associated-ip. | RFC 4388 |
| 93 | Variable. | Client System Architecture Type. | RFC 4578 |
| 94 | Variable. | Client Network Interface Identifier. | RFC 4578 |
| 95 | Variable. | LDAP, Lightweight Directory Access Protocol. | RFC 3679 |
| 96 | RFC 3679 | ||
| 97 | Variable. | Client Machine Identifier. | RFC 4578 |
| 98 | Open Group’s User Authentication. | RFC 2485 | |
| 99 | GEOCONF_CIVIC. | RFC 4776 | |
| 100 | IEEE 1003.1 TZ String. | RFC 4833 | |
| 101 | Reference to the TZ Database. | RFC 4833 | |
| 102 - 111 |
RFC 3679 | ||
| 112 | Variable. | NetInfo Parent Server Address. | RFC 3679 |
| 113 | Variable. | NetInfo Parent Server Tag. | RFC 3679 |
| 114 | Variable. | URL. | RFC 3679 |
| 115 | RFC 3679 | ||
| 116 | 1 | Auto-Configure | RFC 2563 |
| 117 | 2+ | Name Service Search. | RFC 2937 |
| 118 | 4 | Subnet Selection. | RFC 3011 |
| 119 | Variable | DNS domain search list. | RFC 3397 |
| 120 | Variable | SIP Servers DHCP Option. | RFC 3361 |
| 121 | 5+ | Classless Static Route Option. | RFC 3442 |
| 122 | Variable | CCC, CableLabs Client Configuration. | RFC 3495, RFC 3594, RFC 3634 |
| 123 | 16 | GeoConf. | RFC 3825 |
| 124 | Vendor-Identifying Vendor Class. | RFC 3925 | |
| 125 | Vendor-Identifying Vendor-Specific. | RFC 3925 | |
| 126 | RFC 3679 | ||
| 127 | RFC 3679 | ||
| 128 | TFTP Server IP address. | RFC 4578 | |
| 129 | Call Server IP address. | RFC 4578 | |
| 130 | Discrimination string. | RFC 4578 | |
| 131 | Remote statistics server IP address. | RFC 4578 | |
| 132 | 802.1P VLAN ID. | RFC 4578 | |
| 133 | 802.1Q L2 Priority. | RFC 4578 | |
| 134 | Diffserv Code Point. | RFC 4578 | |
| 135 | HTTP Proxy for phone-specific applications. | RFC 4578 | |
| 136 | 4+ | PANA Authentication Agent. | RFC 5192 |
| 137 | variable | LoST Server. | RFC 5223 |
| 138 | CAPWAP Access Controller addresses. | RFC 5417 | |
| 139 | OPTION-IPv4_Address-MoS. | RFC 5678 | |
| 140 | OPTION-IPv4_FQDN-MoS. | RFC 5678 | |
| 141 | 2+ | SIP UA Configuration Service Domains. | RFC 6011 |
| 142 | OPTION-IPv4_Address-ANDSF. | RFC 6153 | |
| 143 | OPTION-IPv6_Address-ANDSF. | RFC 6153 | |
| 144 - 149 |
RFC 3942 | ||
| 150 | TFTP server address. | RFC 5859 | |
| 150 | Etherboot. GRUB configuration path name. |
||
| 151 | status-code. | ||
| 152 | base-time. | ||
| 153 | start-time-of-state. | ||
| 154 | query-start-time. | ||
| 155 | query-end-time. | ||
| 156 | dhcp-state. | ||
| 157 | data-source. | ||
| 158 - 174 |
RFC 3942 | ||
| 175 | Etherboot. | ||
| 176 | IP Telephone. | ||
| 177 | Etherboot. PacketCable and CableHome. |
||
| 178 - 207 |
RFC 3942 | ||
| 208 | pxelinux.magic (string) = F1:00:74:7E (241.0.116.126). | RFC 5071 | |
| 209 | pxelinux.configfile (text). | RFC 5071 | |
| 210 | pxelinux.pathprefix (text). | RFC 5071 | |
| 211 | pxelinux.reboottime (unsigned integer 32 bits). | RFC 5071 | |
| 212 | 18+ | OPTION_6RD. | RFC 5969 |
| 213 | OPTION_V4_ACCESS_DOMAIN. | RFC 5986 | |
| 214 - 219 |
|||
| 220 | Subnet Allocation. | ||
| 221 |
1+
|
Virtual Subnet Selection. | RFC 6607 |
| 222 223 |
RFC 3942 | ||
| 224 - 254 |
Private use. | ||
| 255 | 0 | End. | RFC 2132 |
Glossary:
RFCs:
[RFC 2132] DHCP Options and BOOTP Vendor Extensions.
- Category: Standards Track.
- Updated by:
RFC 3942, RFC 4361. - Obsoletes:
RFC 1533.
[RFC 5417] Control And Provisioning of Wireless Access Points (CAPWAP) Access Controller DHCP Option.
- Category: Standards Track.
- Defines DHCP option 138 (CAPWAP Access Controller addresses).
- Defines DHCPv6 option 52 (CAPWAP Access Controller addresses).
[RFC 6011] Session Initiation Protocol (SIP) User Agent Configuration.
- Category: Informational.
- Defines DHCP option 141 (SIP UA Configuration Service Domains).
- Defines DHCPv6 option 58 (OPTION_SIP_UA_CS_LIST).
[RFC 6607] Virtual Subnet Selection Options for DHCPv4 and DHCPv6.
- Category: Standards Track.
- Defines DHCP option 221 (Virtual Subnet Selection).
- Defines DHCP option 82 suboption 151 (DHCPv4 Virtual Subnet Selection).
- Defines DHCP option 82 suboption 152 (DHCPv4 Virtual Subnet Selection Control).
- Defines DHCPv6 option 68 (Virtual Subnet Selection).
- Updates:
RFC 3046.
Publications:
http://www.networksorcery.com/enp/protocol/bootp/options.htm#Publications
http://www.networksorcery.com/enp/protocol/bootp/options.htm#Publications
Obsolete RFCs:
[ RFC 2489] Procedure for Defining New DHCP Options.
- BCP: 29.
- Obsoleted by:
RFC 2939.
http://www.networksorcery.com/enp/protocol/bootp/options.htm#Description