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    Does pfSense support A clsss DHCP?

    Scheduled Pinned Locked Moved DHCP and DNS
    11 Posts 4 Posters 2.0k Views
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    • D Offline
      doktornotor Banned
      last edited by

      /24 = 255.255.255.0
      /8 = 255.0.0.0 = 16M IPs and that thing would eat 5.1GB of RAM doing nothing all all, just to create the scope.

      Please, stick to SANE values for your subnet.

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      • emammadovE Offline
        emammadov
        last edited by

        I have 4GB of RAM, maybe according to low ram memory, it is not working. Could you please let me know how much RAM Memory does pfSense need for C class and also B class networks at all?

        Elvin

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        • D Offline
          doktornotor Banned
          last edited by

          304 bytes per IP in scope. There is no such thing as A/B/C class. You can have DHCP running perfectly fine with whatever valid subnet on pfSense, but again: Please, stick to SANE values for your subnet.

          Why do you need hundreds of thousands/millions of hosts on same subnet/broadcast domain? Very broken design.

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          • DerelictD Offline
            Derelict LAYER 8 Netgate
            last edited by

            What about 18 billion billion in a /64?

            The size of the netmask doesn't really matter.

            It's the number of active hosts in the broadcast domain that matters.

            Still a silly question.

            Chattanooga, Tennessee, USA
            A comprehensive network diagram is worth 10,000 words and 15 conference calls.
            DO NOT set a source address/port in a port forward or firewall rule unless you KNOW you need it!
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            • D Offline
              doktornotor Banned
              last edited by

              Things are handled differently there. ISC DHCP will either crash on /8 scope (overflows 32bit allocation space), or refuse the configuration. So here, netmask DOES matter. Active or not doesn't matter either there, the memory is usedwasted to create the scope itself.

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              • DerelictD Offline
                Derelict LAYER 8 Netgate
                last edited by

                Hmm. Thanks. Never actually tried a 32-bit /8 scope merp.

                Chattanooga, Tennessee, USA
                A comprehensive network diagram is worth 10,000 words and 15 conference calls.
                DO NOT set a source address/port in a port forward or firewall rule unless you KNOW you need it!
                Do Not Chat For Help! NO_WAN_EGRESS(TM)

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                • D Offline
                  doktornotor Banned
                  last edited by

                  Here's the "Dude, hit yourself with a cluebat" message from fixed versions:

                  
                  /etc/dhcp/dhcpd.conf line 13: 10.0.0.2-10.255.255.254 is an overly large address range.
                  
                  

                  Others just segfault. (But, your box may crash sooner than you get there if you are low on RAM.)

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                  • emammadovE Offline
                    emammadov
                    last edited by

                    I am new in pfSense. So my questions may come strange to you. We have more than 300 devices at our office, so we need at least B class network. Because C class network contains maximum 254 ip. I have 4Gb of RAM memory available at the moment. When I change DHCP scope from 192.168.2.1 to either (172.16.0.0\16 or 10.0.0.1\8), DHCP stops working. I wonder why this happens? And how much Ram memory do I need for pfsense installation firstly?

                    Elvin

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                    • D Offline
                      doktornotor Banned
                      last edited by

                      Let me repeat: There is no such thing as class A, B, C. Need more IPs? Use /23 instead of /24. Or /22. Or /21. But NOT /8.

                      Google: subnet calculator.

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                      • johnpozJ Offline
                        johnpoz LAYER 8 Global Moderator
                        last edited by

                        "We have more than 300 devices at our office"

                        Ok then use /23 that would give you 510 IPs to work.. More than enough IPs with room for growth even.

                        A /8 or /16 is not really a valid host mask.. Those masks are good for summary routing, firewall rules, etc..  But not meant to be used on an actual network with hosts. A /8 gives you 16.7 million IPs - you would never want anywhere close to that on the same broadcast domain..  To be honest /22 could be considered too many, unless are quiet hosts.. If they love to squawk broadcast/multicast like windows yeah prob too many..

                        Your other option when you go over the /24 for hosts is to segment your network.  So all your hosts need to be on the same L2/Broadcast domain??  Do you not have different stuff, servers, printers, users, wifi that you might want to keep from talking to each other..  Different departments - Sales, Engineer, Finance, etc.. So you put them on different networks/vlans with pfsense say using /24 networks so 250 IPs each to work with and now you can firewall between them..

                        As mentioned already multiple times Classful networks A,B,C etc.. have been dead for long time - not sure where your getting your info.. But cidr (classless inter domain routing) or VLSM (variable length subnet masking) has been the standard since introduced - early 90's if I recall..  So to be honest unless your older then I am you shouldn't even remember having to be limited to classful.. I sure don't ;)  And I have been working with networking before tcp/ip was even a thing.. hehehe  I have been working on computers since before there really were computers and networks, and honestly do not recall ever being limited to classful masks.. Was never in a spot where oh.. yeah we need more than /24 have to use /16..  Back then used IPX and or netbeui and do recall having to go around and actually install tcp/ip on all the work computers.. Sweet 386's and 486's and such running windows for workgroups 3.1 etc..

                        Back then there were not so many devices that /24 wasn't HUGE…

                        An intelligent man is sometimes forced to be drunk to spend time with his fools
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