Appendix A – DHCPv4 options
A DHCP server can provide optional configuration settings to clients. Sophos Firewall supports the following DHCP options.
To set the options, see DHCP.
Note
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| Option number | Name | Description | Data type | Data format | Data value (example) | RFC |
|---|---|---|---|---|---|---|
| 2 | Time_Offset | Time offset in seconds from Coordinated Universal Time (UTC) | Four-byte numeric value | Four-byte numeric value | 18000 | RFC 2132 |
| 4 | Time_Servers | N/4 time server addresses | Array of IP addresses | array of | "192.0.2.10,192.0.2.11" | RFC 2132 |
| 5 | IEN116_Name_Servers | N/4 IEN-116 server addresses | Array of IP addresses | array of | "192.0.2.5,192.0.2.6" | RFC 2132 |
| 6 | Domain_Name_Servers | DNS name servers list | Array of IP addresses | array of | "192.0.2.1,192.0.2.2" | RFC 2132 |
| 7 | Log_Servers | N/4 logging server addresses | Array of IP addresses | array of | "192.0.2.7" | RFC 2132 |
| 8 | Cookie_Servers | N/4 quote server addresses | Array of IP addresses | array of | "192.0.2.8" | RFC 2132 |
| 9 | LPR_Servers | N/4 printer server addresses | Array of IP addresses | array of | "192.0.2.9" | RFC 2132 |
| 10 | Impress_Servers | N/4 impress server addresses | Array of IP addresses | array of | "192.0.2.10" | RFC 2132 |
| 11 | Resource_Location_Servers | N/4 RLP server addresses | Array of IP addresses | array of | "192.0.2.11" | RFC 2132 |
| 12 | Host_Name | Client host name | String | String | "myhost.example.com" | RFC 2132 |
| 13 | Boot_Size | Boot file size in 512-byte blocks | Two-byte numeric value | Two-byte numeric value | 512 | RFC 2132 |
| 14 | Merit_Dump | Path for client core dump file | String | String | "/var/crash/dump" | RFC 2132 |
| 15 | Domain_Name | Domain name for client DNS resolution | String | fqdn | "example.com" | RFC 2132 |
| 16 | Swap_Server | Swap server addresses | IP addresses | ipv4-address | "192.0.2.16" | RFC 2132 |
| 17 | Root_Path | Client root disk path | String | String | "/export/root" | RFC 2132 |
| 18 | Extension_Path | Extensions path for TFTP options file | String | String | "/tftp/extensions" | RFC 2132 |
| 19 | IP_Forwarding | Enable or disable IP forwarding | Boolean | Boolean | on | RFC 2132 |
| 20 | Non_Local_Source_Routing | Enable or disable source routing | Boolean | Boolean | off | RFC 2132 |
| 21 | Policy_Filter | Policy filter for non-local source routing | Array of IP addresses | array of | "10.229.0.128,255.255.255.128,10.27.129.0,255.255.255.0" | RFC 2132 |
| 22 | Max_Dgram_Resssembly | Maximum datagram reassembly size | Two-byte numeric value | Two-byte numeric value | 576 | RFC 2132 |
| 23 | Default_IP_TTL | Default IP Time-to-Live value | One-byte numeric value | One-byte numeric value | 64 | RFC 2132 |
| 24 | Path_MTU_Aging_Timeout | Path MTU aging timeout in seconds | Four-byte numeric value | Four-byte numeric value | 600 | RFC 2132 |
| 25 | Path_MTU_Plateau_Table | MTU plateau table for Path MTU Discovery | Array of two-byte numeric values | Array of two-byte numeric values | "68,296,508,1006,1492,1500" | RFC 2132 |
| 26 | Interface_MTU | Interface MTU value | Two-byte numeric value | Two-byte numeric value | 1500 | RFC 2132 |
| 27 | All_Subnets_Local | All subnets are local | Boolean | Boolean | on | RFC 2132 |
| 28 | Broadcast_address | Broadcast address | IP addresses | ipv4-address | "192.0.2.255" | RFC 2132 |
| 29 | Perform_Mask_Discovery | Perform mask discovery | Boolean | Boolean | off | RFC 2132 |
| 30 | Mask_Supplier | Provide mask to others | Boolean | Boolean | off | RFC 2132 |
| 31 | Route_Discovery | Perform router discovery | Boolean | Boolean | off | RFC 2132 |
| 32 | Router_Solicitation_Address | Router solicitation address | IP addresses | ipv4-address | "192.0.2.1" | RFC 2132 |
| 33 | Static_Routes | Static route entries (destination/gateway pairs) | Array of IP addresses | array of | "10.0.0.0,192.0.2.1,172.16.0.0,192.0.2.1" | RFC 2132 |
| 34 | Trailer_Encapsulation | Trailer encapsulation | Boolean | Boolean | off | RFC 2132 |
| 35 | ARP_Cache_Timeout | ARP cache entry timeout in seconds | Four-byte numeric value | Four-byte numeric value | 60 | RFC 2132 |
| 36 | IEEE802_3_Encapsulation | Ethernet encapsulation | Boolean | Boolean | off | RFC 2132 |
| 37 | Default_TCP_TTL | Default TCP segment TTL value | One-byte numeric value | One-byte numeric value | 64 | RFC 2132 |
| 38 | TCP_Keepalive_Interval | TCP keepalive interval in seconds | Four-byte numeric value | Four-byte numeric value | 7200 | RFC 2132 |
| 39 | TCP_Keepalive_Garbage | TCP keepalive garbage | Boolean | Boolean | on | RFC 2132 |
| 40 | NIS_Domain | Network Information Service domain name | String | String | "nisdomain" | RFC 2132 |
| 41 | NIS_Servers | NIS server addresses list | Array of IP addresses | array of | "192.0.2.41,192.0.2.42" | RFC 2132 |
| 42 | NTP_Servers | NTP server addresses list | Array of IP addresses | array of | "192.0.2.42,192.0.2.43" | RFC 2132 |
| 43 | Vendor_Encapsulated_Options | Vendor-specific encapsulated options | String | String | "0x01020304" | RFC 2132 |
| 44 | Netbios_Name_Servers | NetBIOS name server (WINS) addresses | Array of IP addresses | array of | "192.0.2.44,192.0.2.45" | RFC 2132 |
| 45 | Netbios_DD_Server | NetBIOS datagram distribution server addresses | Array of IP addresses | array of | "192.0.2.45" | RFC 2132 |
| 46 | Netbios_Node_Type | NetBIOS node type | One-byte numeric value | One-byte numeric value | 8 | RFC 2132 |
| 47 | Netbios_Scope | NetBIOS scope identifier | String | String | "mynetbios" | RFC 2132 |
| 48 | Font_Servers | X Window font server addresses | Array of IP addresses | array of | "192.0.2.48" | RFC 2132 |
| 49 | X_Display_Manager | X Window display manager addresses | Array of IP addresses | array of | "192.0.2.49" | RFC 2132 |
| 50 | DHCP_Requested_Address | Requested IP address | IP addresses | ipv4-address | "192.0.2.100" | RFC 2132 |
| 51 | DHCP_Lease_Time | IP address lease time in seconds | Four-byte numeric value | Four-byte numeric value | 86400 | RFC 2132 |
| 52 | DHCP_Option_Overload | Overload sname/file fields | One-byte numeric value | One-byte numeric value | 1 | RFC 2132 |
| 53 | DHCP_Message_Type | DHCP message type identifier | One-byte numeric value | One-byte numeric value | 1 | RFC 2132 |
| 54 | DHCP_Server_Identifier | DHCP server identifier address | IP addresses | ipv4-address | "192.0.2.1" | RFC 2132 |
| 55 | DHCP_Parameter_Request_List | Requested DHCP option codes list | Array of one-byte numeric values | Array of one-byte numeric values | "1,3,6,15,28,51" | RFC 2132 |
| 56 | DHCP_Message | Error or status message from DHCP server | String | String | "Requested address not available" | RFC 2132 |
| 57 | DHCP_Max_Message_Size | Maximum DHCP message size accepted by the client | Two-byte numeric value | Two-byte numeric value | 1500 | RFC 2132 |
| 58 | DHCP_Renewal_Time | Renewal (T1) time value in seconds | Four-byte numeric value | Four-byte numeric value | 43200 | RFC 2132 |
| 59 | DHCP_Rebinding_Time | Rebinding (T2) time value in seconds | Four-byte numeric value | Four-byte numeric value | 75600 | RFC 2132 |
| 60 | Vendor_Class_Identifier | Vendor class identifier string | String | String | "MSFT 5.0" | RFC 2132 |
| 61 | DHCP_Client_Identifier | Client unique identifier | String | Hex format data | "1A BB AD AB BA D0 00 00 00 00 00 00 00 00 CA FE" | RFC 2132 |
| 62 | NWIP_Domain | NetWare/IP domain name | String | String | "netware.example.org" | RFC 2242 |
| 63 | NWIP_SubOptions | NetWare/IP suboptions | String | String | "1A BB AD AB BA D0 00 00 00 00 00 00 00 00 CA FE" | RFC 2242 |
| 64 | NISPlus_Domain | NIS+ domain name | String | String | "nisplus.example.org" | RFC 2132 |
| 65 | NISPlus_Servers | NIS+ server addresses | Array of IP addresses | array of | "192.0.2.65" | RFC 2132 |
| 66 | TFTP_Server_Name | TFTP server name | String | String | "tftp.example.org" | RFC 2132 |
| 67 | Bootfile_Name | Boot file name | String | String | "pxelinux.0" | RFC 2132 |
| 68 | Mobile_IP_Home_Agent | Mobile IP home agent addresses | Array of IP addresses | array of | "192.0.2.68" | RFC 2132 |
| 69 | SMTP_Server | Simple Mail Transfer Protocol server addresses | Array of IP addresses | array of | "192.0.2.69" | RFC 2132 |
| 70 | POP_Server | Post Office Protocol server addresses | Array of IP addresses | array of | "192.0.2.70" | RFC 2132 |
| 71 | NNTP_Server | Network News Transfer Protocol server addresses | Array of IP addresses | array of | "192.0.2.71" | RFC 2132 |
| 72 | WWW_Server | WWW server addresses | Array of IP addresses | array of | "192.0.2.72" | RFC 2132 |
| 73 | Finger_Server | Finger server addresses | Array of IP addresses | array of | "192.0.2.73" | RFC 2132 |
| 74 | IRC_Server | Internet Relay Chat server addresses | Array of IP addresses | array of | "192.0.2.74" | RFC 2132 |
| 75 | Streettalk_Server | StreetTalk server addresses | Array of IP addresses | array of | "192.0.2.75" | RFC 2132 |
| 76 | Streettalk_Dir_Asst_Server | StreetTalk directory assistance server addresses | Array of IP addresses | array of | "192.0.2.76" | RFC 2132 |
| 77 | User_Class | User class information | String | String | "engineering" | RFC 3004 |
| 78 | SLP_Directory_Agent | Service Location Protocol directory agent information | String | boolean,array of | "on,192.0.2.78" | RFC 2610 |
| 79 | SLP_Service_Scope | Service Location Protocol service scope information | String | boolean,string | "on,engineering" | RFC 2610 |
| 85 | NDS_Servers | Novell Directory Services server addresses | Array of IP addresses | array of | "192.0.2.85,192.0.2.86" | RFC 2241 |
| 86 | NDS_Tree_Name | Novell Directory Services tree name | String | String | "CORP_TREE" | RFC 2241 |
| 87 | NDS_Context | Novell Directory Services context | String | String | "OU=Engineering.O=Corp" | RFC 2241 |
| 88 | BCMS_Controller_Names | BCMCS controller domain name list | fqdn Array | fqdn Array | "bcms1.example.org,bcms2.example.org" | RFC 4280 |
| 89 | BCMS_Controller_Address | BCMCS controller IPv4 addresses | Array of IP addresses | array of | "192.0.2.89,192.0.2.90" | RFC 4280 |
| 93 | Client_System | Client system architecture type | String | Array of two-byte numeric values | "0,6,7" | RFC 4578 |
| 94 | Client_NDI | Client network device interface identifier | String | Three one-byte numeric values | "1,2,1" | RFC 4578 |
| 97 | UUID_GUID | Client machine UUID/GUID | String | Hex format data | "4d,36,e9,67,11,22,33,44,55,66,77,88,99,aa,bb,cc" | RFC 4578 |
| 98 | UAP_Servers | User Authentication Protocol server addresses | Array of IP addresses | array of | "192.0.2.98" | RFC 2485 |
| 99 | Geoconf_Civic | Civic location configuration information | String | String | "civic-location-data" | RFC 4776 |
| 100 | PCode | Postal code | String | String | "SW1A1AA" | RFC 4833 |
| 101 | TCode | Tax area code | String | String | "TCODE001" | RFC 4833 |
| 112 | Netinfo_Server_Address | NetInfo parent server addresses | Array of IP addresses | array of | "192.0.2.112" | RFC 3679 |
| 113 | Netinfo_Server_Tag | NetInfo parent server tags | String | String | "corporate-netinfo" | RFC 3679 |
| 114 | V4_Captive_Portal | Captive portal URI | String | URI | "https://portal.example.org/captive" | RFC 7710 |
| 116 | Auto_Config | Auto-configuration setting | Boolean | Boolean | on | RFC 2563 |
| 117 | Name_Service_Search | Name service search list | fqdn Array | fqdn Array | "corp.example.org,eng.example.org" | RFC 2937 |
| 119 | Domain_Search | DNS domain search list | fqdn Array | fqdn Array | "example.org,branch.example.org" | RFC 3397 |
| 121 | Classless_Static_Route | Classless static route information | String | array of | "10.0.0.0/8,192.0.2.1,172.16.0.0/12,192.0.2.2" | RFC 3442 |
| 124 | Vivco_Suboptions | Vendor-identifying vendor class suboptions | String | String | "vendor-suboption-data" | RFC 3925 |
| 125 | Vivso_Suboptions | Vendor-identifying vendor-specific suboptions | String | String | "vendor-specific-data" | RFC 3925 |
| 136 | Pana_Agent | PANA agent addresses | Array of IP addresses | array of | "192.0.2.136" | RFC 5192 |
| 137 | V4_Lost | LoST server FQDN | String | fqdn | "lost.example.org" | RFC 5223 |
| 138 | Capwap_AC_V4 | CAPWAP AC addresses | Array of IP addresses | array of | "192.0.2.138" | RFC 5417 |
| 141 | SIP_UA_CS_Domains | SIP UA CS domains | fqdn Array | fqdn Array | "sip.example.org" | RFC 6011 |
| 143 | V4_Sztp_Redirect | Secure ZTP redirect servers | String | array of | "https://sztp1.example.com:8443,https://sztp2.example.com:8444" | RFC 8572 |
| 146 | Rdnss_Selection | RDNSS selection information | String | One-byte numeric value, IPv4 address, IPv4 address, array of | "1,192.0.2.70,192.0.2.71,example.com,example.org" | RFC 6731 |
| 159 | V4_Portparams | Port parameters | String | uint8,PSID | "2,3/4" | RFC 7618 |
| 212 | Option_6rd | IPv6 Rapid Deployment configuration | String | One-byte numeric value, One-byte numeric value, IPv6 address, array of | "24,96,2001:db8::f001,192.0.2.72,192.0.2.73" | RFC 5969 |
| 213 | V4_Access_Domain | Access network domain name | String | fqdn | "access.example.org" | RFC 5986 |
| Custom | Custom | Create a custom DHCP option. Specify the option code, select the option type, and enter the option value. | User-defined | Depends on the selected type | User-defined | N/A |