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    DHCP and DNS in routed network

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    DHCP and DNS
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    • S
      SteveITS Rebel Alliance @astar
      last edited by

      @astar As in, you want VLAN3 to have DHCP? Is that an interface on pfSense? If so it can have its own DHCP server.

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      • johnpozJ
        johnpoz LAYER 8 Global Moderator @astar
        last edited by

        @astar if your vlan01 there is a transit and the L2 for your downstream networks is not connected to pfsense then no pfsense can not be a dhcp server for it - unless I missed some sort of release notes for 2.7 or 23.05 where they added that function.

        For pfsense to provide dhcp, it has to be connected to the network... It can be a relay if you have other dhcpd that has scopes for the different networks. But it can not be the server end on a relay where it hands out dhcp scopes for the downstream networks.

        It can for sure do dns for anything that can talk to it, but can only provide dhcp for networks it has an interface in.

        An intelligent man is sometimes forced to be drunk to spend time with his fools
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        • A
          astar @johnpoz
          last edited by

          The ASCII art lost it's format when it posted, typical.

          Thanks for the help guys. Steven's input is what I have arrived at too. I figured the DHCP server would not support it.

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          • JKnottJ
            JKnott @astar
            last edited by

            @astar

            Why does a routed network make a difference? You can have a DHCP server on each interface. You only need 1 DNS server for your entire network. I have a DNS server enabled for local addresses and use the resolver for external addresses.

            PfSense running on Qotom mini PC
            i5 CPU, 4 GB memory, 32 GB SSD & 4 Intel Gb Ethernet ports.
            UniFi AC-Lite access point

            I haven't lost my mind. It's around here...somewhere...

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            • johnpozJ
              johnpoz LAYER 8 Global Moderator @JKnott
              last edited by

              @JKnott said in DHCP and DNS in routed network:

              Why does a routed network make a difference?

              because if pfsense does not have a leg in the network, you can not setup dhcp server.

              If you have some downstream networks that are routed at a downstream router, pfsense wouldn't have an interface actually in the network..

              An intelligent man is sometimes forced to be drunk to spend time with his fools
              If you get confused: Listen to the Music Play
              Please don't Chat/PM me for help, unless mod related
              SG-4860 24.11 | Lab VMs 2.7.2, 24.11

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              • E
                Ethereal @johnpoz
                last edited by

                @johnpoz
                so I have a question around DHCP for remote networks.
                Why this feature has not been implemented yet with pfsense? are there any challenges ?
                This is quite a common feature (when used with DHCP relay/IP helper) and to me it's a bit absurd that pfsense has to have an interface in the network so it can provide leases.

                Cheers!

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                • S
                  SteveITS Rebel Alliance @Ethereal
                  last edited by

                  @Ethereal Something else would have to relay.

                  DHCP is basically the device asking โ€œcan anyone give me an address?โ€ If there were two DHCP servers on a network with different settings, either may answer first.

                  Pre-2.7.2/23.09: Only install packages for your version, or risk breaking it. Select your branch in System/Update/Update Settings.
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                  Upvote ๐Ÿ‘ helpful posts!

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                  • E
                    Ethereal @SteveITS
                    last edited by

                    @SteveITS the relay is always done by the router of the network where the host asking for a lease, sits. These frames are L2 and don't go outside the broadcast domain.

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                    • S
                      SteveITS Rebel Alliance @Ethereal
                      last edited by

                      @Ethereal ok but in this scenario thatโ€™s not pfSense, correct? If the request is forwarded to pfSense how does pfSense know for what other network it should answer?

                      Pre-2.7.2/23.09: Only install packages for your version, or risk breaking it. Select your branch in System/Update/Update Settings.
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                      • johnpozJ
                        johnpoz LAYER 8 Global Moderator @Ethereal
                        last edited by

                        @Ethereal pfsense does not support setting a scope for a non directly connected network maybe with the dhcpd that is coming they will that function?

                        An intelligent man is sometimes forced to be drunk to spend time with his fools
                        If you get confused: Listen to the Music Play
                        Please don't Chat/PM me for help, unless mod related
                        SG-4860 24.11 | Lab VMs 2.7.2, 24.11

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                        • AndyRHA
                          AndyRH @SteveITS
                          last edited by

                          @SteveITS said in DHCP and DNS in routed network:

                          If the request is forwarded to pfSense how does pfSense know for what other network it should answer?

                          If pfSense did support this common feature, the relay sees the broadcast, sends a directed packet to the DHCP server including subnet information. The DHCP server responds with the lease information. The relay then responds with a broadcast to the original requester with the DHCP lease information. Works great in large networks.
                          Maybe the rumors of a change in DHCP server for pfSense will add this feature.

                          o||||o
                          7100-1u

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                          • E
                            Ethereal @AndyRH
                            last edited by

                            @AndyRH I'm glad to see that there are many people out there asking for this feature to be implemented.

                            S johnpozJ 2 Replies Last reply Reply Quote 0
                            • S
                              SteveITS Rebel Alliance @Ethereal
                              last edited by

                              I understand the request now. In a very quick search I found this 7 year old thread saying it doesn't work in Kea but maybe they have added it since.

                              https://lists.isc.org/mailman/htdig/kea-users/2016-December/000707.html

                              ref: Replace ISC DHCP server with Kea: https://redmine.pfsense.org/issues/6960

                              Pre-2.7.2/23.09: Only install packages for your version, or risk breaking it. Select your branch in System/Update/Update Settings.
                              When upgrading, allow 10-15 minutes to restart, or more depending on packages and device speed.
                              Upvote ๐Ÿ‘ helpful posts!

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                              • johnpozJ
                                johnpoz LAYER 8 Global Moderator @Ethereal
                                last edited by johnpoz

                                @Ethereal said in DHCP and DNS in routed network:

                                many people

                                Define many? If you mean a few here and there as many - ok ;) hehehe

                                Most networks that get to the stage that they are routing downstream run their own dhcpd, and not off their edge router..

                                An intelligent man is sometimes forced to be drunk to spend time with his fools
                                If you get confused: Listen to the Music Play
                                Please don't Chat/PM me for help, unless mod related
                                SG-4860 24.11 | Lab VMs 2.7.2, 24.11

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                                • AndyRHA
                                  AndyRH
                                  last edited by

                                  If you use the Customer Service complaint theory, only a low percentage of people will complain, most just go somewhere else.
                                  In the last few months I have seen 3 or 4 posts in some way related to DHCP relay. So 3 times some number that just do something else. That total has to be more than a few dozen. Enough to warrant adding the feature, maybe. If relay is a feature of KEA (I have found no evidence it is) then it would be wise to implement it.
                                  In a lab environment relay would be nice so it can be used for practice.
                                  I am more after the feature to add a reservation in the range, which appears to be a feature. It just makes it easier for me and I do not have IP address OCD so I am cool with "random" reservations.

                                  o||||o
                                  7100-1u

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                                  • E
                                    Ethereal @johnpoz
                                    last edited by

                                    @johnpoz hahahaha yeah, well in my defense there are a few posts on this forum around this feature. People (like me) are a bit surprised that this is not supported and in the same time a bit disapointed, since it's quite a basic feature.
                                    In the same time, you're not wrong about the dedicated DHCP server.
                                    Myself I have the scopes configured on my 3750x switch, however would love to have them configured on the pfsense box. I love the gui, I can't help it.

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