How to Configure DHCP Option 2 (Time Offset) in the SonicWall

10/14/2021 1,075 People found this article helpful 107,609 Views

Description

The SonicWall DHCP server options feature provides support for DHCP options, also known as vendor extensions, as defined primarily in RFCs 2131 and 2132. DHCP options allow users to specify additional DHCP parameters in the form of pre-defined, vendor-specific information that is stored in the options field of a DHCP message. When the DHCP message is sent to clients on the network, it provides vendor-specific configuration and service information.

"The time offset field specifies the offset of the client's subnet in seconds from Coordinated Universal Time (UTC). The offset is expressed as a two's complement 32-bit integer. A positive offset indicates a location east of the zero meridian and a negative offset indicates a location west of the zero meridian. The code for the time offset option is 2, and its length is 4 octets" RFC 2132.

The following table gives the conversion of the different time zones around the world. The hexadecimal values are set to have a fixed length of 32 bits as specified in Option 2 of the DHCP RFC 2132. SonicWall does not accept negative numbers for the time offset, Hex must be used.

GMT offset (in hr)	GMT offset in seconds	GMT offset in Hexadecimal
0	0	0x00000000
+1	3600	0x00000E10
+2	7200	0x00001C20
+3	10800	0x00002A30
+4	14400	0x00003840
+5	18000	0x00004650
+6	21600	0x00005460
+7	25200	0x00006270
+8	28800	0x00007080
+9	32400	0x00007E90
+10	36000	0x00008CA0
+11	39600	0x00009AB0
+12	43200	0x0000A8CD
-1	N/A	0xFFFFF1F0
-2	N/A	0xFFFFE3E0
-3	N/A	0xFFFFD5D0
-4	N/A	0xFFFFC7CD
-5	N/A	0xFFFFB9B0
-6	N/A	0xFFFFABA0
-7	N/A	0xFFFF9D90
-8	N/A	0xFFFF8F80
-9	N/A	0xFFFF8170
-10	N/A	0xFFFF7360
-11	N/A	0xFFFF6550

Resolution

Resolution for SonicOS 6.5

This release includes significant user interface changes and many new features that are different from the SonicOS 6.2 and earlier firmware. The below resolution is for customers using SonicOS 6.5 firmware.

To configure DHCP Option objects, perform the following steps:

Login to the SonicWall Mangement GUI

Click Manage in the top navigation menu
Navigate to the Network | DHCP Server page.
Click on the Advanced button alonside the Enable DHCP Server check-box.
In the DHCP Advanced Settings window,
Click on the Add Option.. button.
In the Add DHCP Option Object window, enter the following:
Option Name: Enter a name for this object
Option Number: Select 2 (Time Offset)
Under Option Value, enter the offset value in hexadecimal. For example:0xFFFF8F80.
Enable check box Option Array to enter multiple values separated by a semi-colon (;). For example: 0xFFFF8F80;0x00009AB0. Click on OK to save.

Resolution for SonicOS 6.2 and Below

The below resolution is for customers using SonicOS 6.2 and earlier firmware. For firewalls that are generation 6 and newer we suggest to upgrade to the latest general release of SonicOS 6.5 firmware.

To configure DHCP Option objects, perform the following steps:

Login to the SonicWall Mangement GUI
Navigate to the Network | DHCP Server page.
Click on the Advanced button alonside the Enable DHCP Server check-box. Note: In Gen4 devices the Option Objects button is under DHCP Server Lease Scopes. Although the screenshots in the KB article are of a Gen4 NSA device, the options are similar in Gen3 devices.
In the DHCP Advanced Settings window, click on the Add Option.. button.
In the Add DHCP Option Object window, enter the following:
Option Name: Enter a name for this object
Option Number: Select 2 (Time Offset)
Under Option Value, enter the offset value in hexadecimal. For example:0xFFFF8F80.
Enable check box Option Array to enter multiple values separated by a semi-colon (;). For example: 0xFFFF8F80;0x00009AB0.
Click on OK to save.