DHCP Server not working

[Eria211]

Hi, I seem to have a very strange issue on my SG 3100

I had an older pfsense box and I have restored the backup of that to the SG 3100 and changed a few settings (like enabled the hardware offloading) and DHCP does not work

The log is full of:

parse_option_buffer: malformed option vendor-class.<unknown> (code 1027): code tag at end of buffer - missing length field.

I get DHCPDISCOVER, DHCPOFFER, and the odd DHCPACK over and over again but nothing actually gets an IP

I only have 1 dhcp server running:
4686 - Ss 0:00.22 /usr/local/sbin/dhcpd -user dhcpd -group _dhcp -chroot
11793 - S 0:00.00 sh -c ps ax | grep dhcpd 2>&1
12296 - S 0:00.00 grep dhcpd
68167 - Ss 0:07.37 /usr/sbin/syslogd -s -c -c -l /var/dhcpd/var/run/log -P

Ive restarted the service, restarted the pfsense appliance, ive removed all VOIP phone options from the DHCP options, ive restarted interfaces, I dont know what else to try

[Eria211]

I have managed to get 2 devices to accept a lease but they show in Status / DHCP Leases as offline and they continually show in the logs offering / discovering

[Eria211]

@Eria211 said in DHCP Server not working:

parse_option_buffer: malformed option vendor-class.<unknown> (code 1027): code tag at end of buffer - missing length field.

I dont think the error is relevant:

parse_option_buffer: malformed option vendor-class.<unknown> (code 1027): code tag at end of buffer - missing length field.

As from browsing the logs on the old pfsense appliance we had it had been happening for months so its not the reason the dhcp is not working

The main symptom seems to be that most devices dont send the acknowledgement of the offer they receive

[Gertjan]

Hi,

This https://www.isc.org/dhcp/ is the home of the DHCP server used in pfSense.

All over the world, at any time, it serves millions of DHCP leases a second, and yet, you have a network full of devices that can't work with it ? Possible, how long did it take for you to to find a collection of devices that won't work with ISC DHCP server ??

Good news : I'm pretty sure you can remove all issues within a couple of minutes.

Step 1 : save your pfsense config 'somewhere'.
Step 2 : reduce your network to "simple" : pfSense, a (lot of) switch(es) - and your wired devices.
Step3 : reset pfSense. Assign a WAN interface and LAN interface. Accept default values everywhere. Make work the WAN interface - change the password if you have to. And do nothing else. These words are critical : "Do nothing else".
Step 4 : your DHCP issue is gone, all your devices obtain a DHCP lease from pfSense.
Done.

Btw :

parse_option_buffer: malformed option vendor-class.<unknown> (code 1027):

The DHCP option code "1027" is some DHCP code that some device wants.
This device needs a known de find DHCP server that can understand this "1027", and has an answer for it.
Such a situation exists when you use equipment from your ISP that needs the presence of the ISP router - and DHCP server. A generic router with DHCP server doesn't know anything about "DHCP option "1027".
=> Consider creating this "1027" yourself in the DHCP settings.

See here for an example of known option numbers.

[Eria211]

If it needs to be stated, I don't have a collection of devices that won't work with the implementation of DHCP in pfsense, I have a problem that is stopping it from working, likely what I have done by restoring a backup from a non netgate appliance to a netgate appliance, but still a problem im facing.

However many leases are issued per second globally doesn't help me, I can't get the system to work

I have contacted netgate support and have been sent an image to flash onto the 3100 so that I can start again from scratch and not use my backup from the previous device

I will restore each setting from the previous pfsense appliance one by one and I will try to follow the order that you suggest

Good to know on the option code 1027, I haven't a clue what device is chirping about it but all devices worked on the previous appliance and whatever this device is has no problem not getting option 1027 so I will continue to ignore it

It's just a shame that there doesn't seem to be a way to resolve this issue without flashing the device, but again, it was likely inappropriate to try to restore a 3rd party devices config to a netgate appliance