Appendix A – DHCP Options (RFC 2132)
A DHCP server can provide optional configurations to the client. Sophos Firewall provides support to configure following DHCP Options as defined in RFC 2132.
To set the options, refer to DHCP Management section.
| Option Number | Name | Description | Data Type |
|---|---|---|---|
| 2 | Time offset | Time offset in seconds from UTC | Four-byte numeric value |
| 4 | Time servers | N/4 time server addresses | Array of IP addresses |
| 5 | Name servers | N/4 IEN-116 server addresses | Array of IP addresses |
| 7 | Log servers | N/4 logging server addresses | Array of IP addresses |
| 8 | Cookie servers | N/4 quote server addresses | Array of IP addresses |
| 9 | LPR servers | N/4 printer server addresses | Array of IP addresses |
| 10 | Impress servers | N/4 impress server addresses | Array of IP addresses |
| 11 | RLP servers | N/4 RLP server addresses | Array of IP addresses |
| 12 | Host name | Hostname string | String |
| 13 | Boot file size | Size of boot file in 512 byte chunks | Two-byte numeric Value |
| 14 | Merit dump file | Client to dump and name of file to dump to | String |
| 16 | Swap server | Swap server addresses | IP address |
| 17 | Root path | Path name for root disk | String |
| 18 | Extension file | Patch name for more BOOTP info | String |
| 19 | IP layer forwarding | Enable or disable IP forwarding | Boolean |
| 20 | Src route enabler | Enable or disable source routing | Boolean |
| 22 | Maximum DG reassembly size | Maximum datagram reassembly size | Two-byte numeric value |
| 23 | Default IP TTL | Default IP time-to-live | One-byte numeric value |
| 24 | Path MTU aging timeout | Path MTU aging timeout | Four-byte numeric value |
| 25 | MTU plateau | Path MTU plateau table | Array of two-byte numeric values |
| 26 | Interface MTU Size | Interface MTU size | Two-byte numeric value |
| 27 | All subnets are local | All subnets are local | Boolean |
| 28 | Broadcast address | Broadcast address | IP address |
| 29 | Perform mask discovery | Perform mask discovery | Boolean |
| 30 | Provide mask to others | Provide mask to others | Boolean |
| 31 | Perform router discovery | Perform router discovery | Boolean |
| 32 | Router solicitation address | Router solicitation address | IP address |
| 34 | Trailer encapsulation | Trailer encapsulation | Boolean |
| 35 | ARP cache timeout | ARP cache timeout | Four-byte numeric value |
| 36 | Ethernet encapsulation | Ethernet encapsulation | Boolean |
| 37 | Default TCP TTL | Default TCP TTL | One-byte numeric value |
| 38 | TCP keepalive interval | TCP keepalive interval | Four-byte numeric value |
| 39 | TCP keepalive garbage | TCP keepalive garbage | Boolean |
| 40 | NIS domain name | NIS domain name | String |
| 41 | NIS server addresses | NIS server addresses | Array of IP addresses |
| 42 | NTP servers addresses | NTP servers addresses | Array of IP addresses |
| 43 | Vendor specific information | Vendor specific information | String |
| 45 | NetBIOS datagram distribution | NetBIOS datagram distribution | Array of IP addresses |
| 46 | NetBIOS node type | NetBIOS node type | One-byte numeric Value |
| 47 | NetBIOS scope | NetBIOS scope | String |
| 48 | X window font server | X window font server | Array of IP addresses |
| 49 | X window display manager | X window display manager | Array of IP addresses |
| 50 | Requested IP address | Requested IP address | IP addresses |
| 51 | IP address lease time | IP address lease time | Four-byte numeric value |
| 52 | Option overload | Overload “sname” or “file” | One-byte numeric value |
| 53 | DHCP message type | DHCP message type | One-byte numeric value |
| 55 | Parameter Request List | Parameter request list | Array of one-byte numeric values |
| 56 | Message | DHCP error message | String |
| 57 | DHCP maximum message size | DHCP maximum message size | Two-byte numeric value |
| 58 | Renew time value | DHCP renewal (T1) time | Four-byte numeric value |
| 59 | Rebinding time value | DHCP rebinding (T2) time | Four-byte numeric value |
| 60 | Client identifier | Client identifier | String |
| 61 | Client identifier | Client identifier | String |
| 62 | Netware/IP domain name | Netware/IP domain name | String |
| 64 | NIS+ V3 client domain name | NIS+ V3 client domain name | String |
| 65 | NIS+ V3 server address | NIS+ V3 server address | Array of IP addresses |
| 66 | TFTP server name | TFTP server name | String |
| 67 | Boot file name | Boot file name | String |
| 68 | Home agent addresses | Home agent addresses | Array of IP addresses |
| 69 | Simple mail server addresses | Simple mail server addresses | Array of IP addresses |
| 70 | Post office server addresses | Post office server addresses | Array of IP addresses |
| 71 | Network news server addresses | Network news server addresses | Array of IP addresses |
| 72 | WWW server addresses | WWW server addresses | Array of IP addresses |
| 73 | Finger server addresses | Finger server addresses | Array of IP addresses |
| 74 | Chat server addresses | Chat server addresses | Array of IP addresses |
| 75 | StreetTalk server addresses | StreetTalk server addresses | Array of IP addresses |
| 76 | StreetTalk directory assistance addresses | StreetTalk directory assistance addresses | Array of IP addresses |
| 120 | SIP server | The SIP server DHCP option carries a 32-bit (binary) IPv4 address used by the SIP client to locate a SIP server. | Array of IP addresses |
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