Hot!Time Offset sent as DHCP option 2 not correct

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HDClown
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2019/05/13 09:20:45 (permalink)
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Time Offset sent as DHCP option 2 not correct

60E on 6.0.4.  I am using the FGT as DHCP server.  The FGT itself has timezone and offset (-5 hours Eastern) and reflects the correct time in the dashboard.  The DHCP server on the FGT is defined with "set timezone-option specify" and "set timezone 12" where "12" corresponds to -5 Eastern per "set timezone ?".
 
The problem is, the FGT DHCP server is sending out option 2 time offset of -14400s which is -4  hours.  I've confirmed this with a packet capture made on the FGT and viewed in WireShark.  It should be sending -18000s or -5 hours.
 
If I set the DHCP server to "set timezone-option default" I still have the same problem, the time offset is still -4
 
Anyone seen this issue before?
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    ede_pfau
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    Re: Time Offset sent as DHCP option 2 not correct 2019/05/13 10:45:47 (permalink)
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    just an idea...some DHCP options have to be specified in hex. If you enter "12" is would mean 12hex = 18dec. But I haven't checked this.
    Another idea: do you have DST enabled?

    Ede

    " Kernel panic: Aiee, killing interrupt handler!"
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    HDClown
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    Re: Time Offset sent as DHCP option 2 not correct 2019/05/13 10:53:58 (permalink)
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    ede_pfau
    just an idea...some DHCP options have to be specified in hex. If you enter "12" is would mean 12hex = 18dec. But I haven't checked this.

     
    DHCP option 2 is controlled by the DHCP advanced option of "Time Zone" in the GUI, which lets you choose "Same as System" or "Specify".  When you use "Same as System" you end up in the CLI with "set timezone-option default" with nothing showing for "set timezone".  If you use "Specify" than you have in the CLI "set timezone-option specify" and "set timezone 12" (in my case since I am choosing Eastern in the GUI)
     
    The "12" is just some translation FortiOS is using internally.  It seems like there is something going on as it relates to that translation and DST.
     
    You actually can't manually specify DHCP Option 2 as a custom option.   It tells you "Option is in use as DHCP setting: timezone-option, timezone" which is being setup by the option GUI setting.  If I could set option 2 this way, I could makes sure the correct value is being sent,
      

    Another idea: do you have DST enabled?



    DST is enabled by default. I confirmed this by doing "set dst enable" under "config system global" but it doesn't display an entry under "show system global", indicating that is the default.
    post edited by HDClown - 2019/05/13 10:56:03
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