• Recent
    • Unsolved
    • Tags
    • Popular
    • Users
    • Groups
    • Search
    • Register
    • Login

    FOG DHCP problems with possible printer interference?

    Scheduled Pinned Locked Moved Unsolved
    FOG Problems
    5
    26
    7.3k
    Loading More Posts
    • Oldest to Newest
    • Newest to Oldest
    • Most Votes
    Reply
    • Reply as topic
    Log in to reply
    This topic has been deleted. Only users with topic management privileges can see it.
    • A
      afriedman
      last edited by

      Hey Tom.

      “A rogue DHCP server”. I don’t see a second DHCP server anywhere on our network, that I’m aware of. Is wireshark one of the only ways to see if there’s a rogue/secret DHCP server hiding somewhere?

      I think there’s a switch in between, but if I even find that switch, would I have to do any type of forwarding with that?

      george1421G 1 Reply Last reply Reply Quote 0
      • george1421G
        george1421 Moderator @afriedman
        last edited by george1421

        @afriedman said in FOG DHCP problems with possible printer interference?:

        Hey Tom.

        “A rogue DHCP server”. I don’t see a second DHCP server anywhere on our network, that I’m aware of. Is wireshark one of the only ways to see if there’s a rogue/secret DHCP server hiding somewhere?

        Yes, wireshark will tell you this. Since dhcp is broadcast traffic, you just need to attach your wireshark computer the subnet where your target computer is and then set your filters for port 67 and port 68 then pxe boot your target computer. You will see a “DHCP Offer” packets from all of the dhcp servers that can hear the initial client dhcp request.

        But in this case I still think its a spanning tree issue.

        Please help us build the FOG community with everyone involved. It's not just about coding - way more we need people to test things, update documentation and most importantly work on uniting the community of people enjoying and working on FOG!

        1 Reply Last reply Reply Quote 0
        • A
          afriedman
          last edited by

          @george1421 Spanning tree issue? Please explain.

          george1421G 1 Reply Last reply Reply Quote 0
          • george1421G
            george1421 Moderator @afriedman
            last edited by george1421

            @afriedman said in FOG DHCP problems with possible printer interference?:

            @george1421 Spanning tree issue? Please explain.

            I thought I did in my first post??

            If you are not using a fast spanning tree protocol the switch port won’t start transmitting data until 27 seconds after the link comes up.

            Please help us build the FOG community with everyone involved. It's not just about coding - way more we need people to test things, update documentation and most importantly work on uniting the community of people enjoying and working on FOG!

            1 Reply Last reply Reply Quote 0
            • george1421G
              george1421 Moderator
              last edited by

              @Joe-Schmitt I think that Sebastian was working on one too using node-js. I’m not sure if is the same one you were working on or not.

              Please help us build the FOG community with everyone involved. It's not just about coding - way more we need people to test things, update documentation and most importantly work on uniting the community of people enjoying and working on FOG!

              1 Reply Last reply Reply Quote 0
              • A
                afriedman
                last edited by

                @george1421 sorry I didn’t see your original post - ill look at that.

                @Joe-Schmitt sounds good. I’ll be waiting for your answer.

                1 Reply Last reply Reply Quote 0
                • A
                  afriedman
                  last edited by

                  @Joe-Schmitt Thank you very much for this program.

                  When I run this program, I should then turn on a different machine in the same area and look at the results on the computer where im running your program?

                  1 Reply Last reply Reply Quote 0
                  • J
                    Joe Schmitt Senior Developer
                    last edited by Joe Schmitt

                    @afriedman Nope, the program will simulate a computer booting up requesting PXE information and capture who responds and with what.

                    Please help us build the FOG community with everyone involved. It's not just about coding - way more we need people to test things, update documentation and most importantly work on uniting the community of people enjoying and working on FOG! Get in contact with me (chat bubble in the top right corner) if you want to join in.

                    1 Reply Last reply Reply Quote 0
                    • A
                      afriedman
                      last edited by

                      @Joe-Schmitt Ahhhhhh okay. I’ll let you know the results very soon!

                      1 Reply Last reply Reply Quote 0
                      • george1421G
                        george1421 Moderator
                        last edited by george1421

                        @Joe-Schmitt Side note: it will need to capture at least two if not more offers from dhcp servers. If we are running dnsmasq you will get two offers right away one from the dhcp server and one from the dhcpProxy server.

                        Please help us build the FOG community with everyone involved. It's not just about coding - way more we need people to test things, update documentation and most importantly work on uniting the community of people enjoying and working on FOG!

                        1 Reply Last reply Reply Quote 0
                        • A
                          afriedman
                          last edited by afriedman

                          @Joe-Schmitt

                          http://imgur.com/a/y57wR

                          The bottom image is the first half, and the top image is the second half.

                          1 Reply Last reply Reply Quote 0
                          • A
                            afriedman
                            last edited by

                            @Joe-Schmitt You weren’t expecting that outcome? Lol interesting.

                            1 Reply Last reply Reply Quote 0
                            • A
                              afriedman
                              last edited by

                              @Joe-Schmitt Oh alright. Well it’s a pretty neat program.

                              @george1421 I’m going to try to talk to Cisco Technical Support either today or tomorrow about having them remote into our switch and turn on one of the fast STP protocols. I’ll let you know the results, unless you’d prefer I do something else before talking to Cisco.

                              george1421G 2 Replies Last reply Reply Quote 0
                              • george1421G
                                george1421 Moderator @afriedman
                                last edited by

                                @afriedman As I said, if you place the dumbest switch you can find (that’s still functional) between your cisco switch and the target computer. Then pxe boot the target computer, if you can get to the fog menu where you couldn’t without the dumb switch, then its most likely a spanning tree issue.

                                I can say typically they would turn on one of the fast STP protocols by default (just for this reason). There have been documented cases of target computers not getting dhcp addresses because of this.

                                Please help us build the FOG community with everyone involved. It's not just about coding - way more we need people to test things, update documentation and most importantly work on uniting the community of people enjoying and working on FOG!

                                1 Reply Last reply Reply Quote 0
                                • george1421G
                                  george1421 Moderator @afriedman
                                  last edited by

                                  @afriedman We’ll just taking with Joe through chat. What he’s seeing and what I thought I say was too different things.

                                  It would be helpful if you can capture a pcap of the pxe booting process.

                                  Please do the following (assuming your fog server, dhcp server, and pxe booting clinet are on the same subnet).

                                  1. Install tcpdump on your fog server
                                  2. Launch the tcpdump program with this command tcpdump -w output.pcap port 67 or port 68 or port 69 or port 4011
                                  3. PXE boot the target computer until you get the error
                                  4. Press ctrl-c to exit out of the tcpdump program
                                  5. Upload the pcap file here for review.

                                  Please help us build the FOG community with everyone involved. It's not just about coding - way more we need people to test things, update documentation and most importantly work on uniting the community of people enjoying and working on FOG!

                                  1 Reply Last reply Reply Quote 1
                                  • A
                                    afriedman
                                    last edited by

                                    @george1421

                                    Amazing!! I just used a dumb switch in between that trouble computer, and it booted to FOG INSTANTLY, no hesitation.

                                    Still want me to install tcpdump and follow your instructions for it?

                                    george1421G 1 Reply Last reply Reply Quote 0
                                    • george1421G
                                      george1421 Moderator @afriedman
                                      last edited by george1421

                                      @afriedman Yes please that would help understand the data that joe’s script is spitting out.

                                      But you know you need to talk with your network group about the switch configuration too, we kind of have two threads running inside this one.

                                      Please help us build the FOG community with everyone involved. It's not just about coding - way more we need people to test things, update documentation and most importantly work on uniting the community of people enjoying and working on FOG!

                                      1 Reply Last reply Reply Quote 0
                                      • A
                                        afriedman
                                        last edited by

                                        @george1421

                                        Sounds good. I’ll try to run that when I do some work from home tonight.

                                        Yeah I’m waiting on some responses from her. I believe I’ve narrowed it down to 1 specific cluster of computers (about 24-28 of them) in our building. All other 90% of computers see the FOG server with no problems.

                                        I’ll post an update when I can.

                                        1 Reply Last reply Reply Quote 0
                                        • A
                                          afriedman
                                          last edited by

                                          @george1421

                                          Sorry about the delayed response, I was out sick yesterday.

                                          Do you want me to PXE boot a computer that isn’t booting to FOG with the tcpdump program? Or PXE boot a computer that is working with FOG?

                                          george1421G 1 Reply Last reply Reply Quote 0
                                          • george1421G
                                            george1421 Moderator @afriedman
                                            last edited by

                                            @afriedman Thinking about it a bit more, lets hold off on the tcpdump. I think you have a path forward there. Collecting a pcap would be nice to know but not need to know.

                                            IF you are still having issues after you get the spanning tree issues resolved then we can go down that path.

                                            Please help us build the FOG community with everyone involved. It's not just about coding - way more we need people to test things, update documentation and most importantly work on uniting the community of people enjoying and working on FOG!

                                            1 Reply Last reply Reply Quote 0
                                            • 1
                                            • 2
                                            • 1 / 2
                                            • First post
                                              Last post

                                            156

                                            Online

                                            12.0k

                                            Users

                                            17.3k

                                            Topics

                                            155.2k

                                            Posts
                                            Copyright © 2012-2024 FOG Project