Does pfSense support A clsss DHCP?

emammadov

Hello,

I have installed pfSense. I have 2 issues:

1. having done instllation, pfSense doesn't automatically give LAN ip address, in this case I enter LAN ip address manually within pfSense serial console.
2. After changing LAN ip address from C class to A class, it is not working. I enter IP address: 10.0.0.1 Subnet mask: 24 (255.0.0.0) and enable DHCP. But after that it doesn't give ip addresses to devices and I can't access to pfsense web configurator.

Could you please help on this matter?

doktornotor

/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.

emammadov

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?

doktornotor

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.

Derelict

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.

doktornotor

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 ~~used~~wasted to create the scope itself.

Derelict

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

doktornotor

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.)

emammadov

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?

doktornotor

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.

johnpoz

"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…