TFTP boot timing out

  • Hello,

    I have been trying to setup Fog on a company network for a few days now and I have been running into the issue of TFTP boot timing out. Option 66 has been set to “” (the Fog server address). option 67 has been set to “undionly.kpxe” for the bootfile name.

    I am confused on why the “next server” address would be going to the gateway when i beleive it should show the fog server’s IP address to boot from that server…

    DHCP is being handled at the gateway

    Screen Shot 2019-02-21 at 10.49.48 AM.png The client does get a valid IP ( for example.

    Any help would be appriciated on why I would be having a TFTP timeout.

  • Your Fantastic! My system admin and I have been going through as many settings as we could find this week. The Dnsmasq solved it!

    Please mark as read

  • Moderator

    @ethan-s Why yes I do:

    If your pxe booting clients are on a different subnet than the FOG server then you will need to update your dhcp-relay service on your vlan router by adding the FOG server as the last dhcp server in the dhcp relay list.

  • Hello,

    Do you have any instructions/guide on how to setup Dnsmasq with an existing DHCP service?

    Thank you

  • Moderator

    @ethan-s Some (crappy) routers will give out their address instead of the defined next-server address. You should be able to see this if you setup wireshark on a witness computer. Use the capture filter of “port 67 or port 68”. PXE boot the target computer until you get the error then stop wireshark. Look at the DHCP OFFER packet and look to see what next-server is set to.

    If your router isn’t capable of handing out the proper pxe boot information then we can load dnsmasq on your fog server and have your fog server only provide the pxe boot information. The rest of dhcp would be provided by your current dhcp server. So even if you have a misbehaving dhcp server we can get you going.

  • Hello, DHCP is being handled by a Cradlepoint AER2200 router in our environment

    The “next server:” should be looking at the Fog server correct? instead of the DHCP server

  • Developer

    @ethan-s said in TFTP boot timing out:

    Option 66 has been set to “” (the Fog server address).

    The picture clearly shows Next server: - what is serving DHCP in your network?

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