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Wayne11
Contributor

DHCP Options

Hi I' ve a little problem with the DHCP option 78 [link=]http://www.networksorcery.com/enp/rfc/rfc2610.txt[/link] In option 1 " Code" I put in 78 and in the " Option" the Hex code for the IP address 3137322e31372e33362e3630 but the clients don' t receive this option. I think the problem is this Mandatory byte! Novell clients may require the configuration of DHCP options 78 and 79. These options are sometimes referred to as the SLP options. The SLP options (from Request for Comments [rfc] 2610) have an extra flag in the option field that is different than any other DHCP option. This flag is called the Mandatory byte. No other DHCP options for simple address arrays follow this structure. The following example compares SLP options to DCHP options: SLP options: | Code = 78 | Length | Mandatory | a1 | a2 | a3 | a4 | ... All other DHCP options: | Code = 32 | Length | a1 | a2 | a3 | a4 |... This extra byte prevents you from using the IPAddress array type in the snap-in when you add this option. However, you can add the option by creating option 78 as a Byte array and option 79 as an Encapsulated array. How do I have to add this extra Mandatory-byte in the Fortigate DHCP options? Any suggestions? Thx Wayne
4 REPLIES 4
FortiRack_Eric
New Contributor III

Hi The FG calculates the length field itself so don' t supply it, furthermore use capitals for the HEX values. The mandatory field should be supplied. Cheers, Eric

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Wayne11
Contributor

Hi Eric No way, I tried with capitals, with and without length but the clients never received this option Any other suggestions? Thx Wayne
romanr
Valued Contributor

Have you ever tried sniffing (with wireshark) what is being sent by the FGT? Wireshark is able to decode the DHCP options that are sent out! EDIT: BTW: There were changes in the DHCP section of the FGT from 3MR6 to 3MR7! Maybe some update will help as well, if you still got 3MR6! cheers.roman
Wayne11
Contributor

Hi Roman Nope, I will try that with Whireshark as soon as possible and will upgrade to MR7 also. Thx Wayne
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