Multiple Routes with Hex String in DHCP option 249

03/26/2020 6 8005

DESCRIPTION:

This article covers how to configure multiple routes with hex string in DHCP option 249 (Private Use) on a SonicWall firewall.

RESOLUTION:

STEP 1: Create Option Object
Go to Network | DHCP Server screen,

Step 2: Now, click on Advanced,

Step 3: Click DHCP Generic Option drop down Menu and select "Create New DHCP Option Object"

Step 4: Now, you have to fill up all the necessary fields,

OPTION NAME is the name of the object, OPTION NUMBER chosen is "DHCP Option 249" with OPTION ARRAY check-box "DISABLED" and OPTION TYPEset as "HEX STRING".

Example: You have to Add two Routes:

1)Network is 10.56.0.0/16 and Gateway is 10.10.5.253 and 

2)Network is 10.58.0.0/16 and Gateway is 10.10.5.253

When using Option Type as Hex String we have to convert each Decimal to its Hexadecimal value and add them in a continuous line but we have to separate each route with a SPACE/ENTER.

In Order to convert a Decimal to its Hexadecimal value follow this link:

"http://www.binaryhexconverter.com/decimal-to-hex-converter"

Now, before converting the Decimals to Hexadecimals you have to write the whole Route in the following patter:

"16;10;56;10;10;5;253" and start converting the Decimals starting from Left side i.e. 16;x;x;x;x;x;x as shown in the image below:

Now the syntax that we have to use in this scenario goes as follows:

100A380A050101                                   FOR Network 10.56.0.0/16 and Gateway 10.10.5.253 (16;10;56;10;10;5;253)
100A380A050101100A3A0A050101  FOR Network 10.58.0.0/16 and Gateway 10.10.5.253 (16;10;58;10;10;5;253)

Step 5: In order to Verify the same, you can run a packet capture on WIRESHARK and the results should be as follows: