@george1421

Now you said that isc-dhcp server worked?? The reason why I ask is that isc-dhcp server and dnsmasq do the same thing. So why would isc-dhcp server issue IP addresses and dnsmasq does not respond?

To be honest, this is beyond me.

Initially, when I configured the FOG server I installed isc-dhcp server, configured pool of addresses and added “next-server” and “filename”. Then I set bootprelay of the switch to point to the FOG server and everything worked (and still works if I go back to this scenario).
Afterwards I realized that our expensive switch supports dhcp and decided to give it a shot (why use separate service for something that already runs on the switch, right?). Since then I’ve encountered this issue i.e. switch supporting only numerical option codes (66, 67 etc). Analyzing the frames turned out that my clients are unable to evaluate those options even though they do exist in the dhcp packets! Having “next-server” and “Boot file name” in the packet body seemed like the only way it works. I managed to confirm this by analyzing frames coming from my working isc-dhcp server.

Now, you can probably see how strange it is.

@george1421

Thanks, George. I had a look at this. The first link corresponds to the appliance we have. I had a shot with the mentioned configurations (by adding trusted server and dhcp snooping) but that didn’t change a thing.

The second link relates to securestacks and that doesn’t apply to our switch (EXOS). No such commands here.

At this point it seems easier just to stop switch’s built-in DHCP, re-enable the isc-dhcp server on my FOG machine and point bootprelay to it. That’s my working scenario that I used few days ago, and also what makes everything so frustrating.

@george1421

I’ve stopped and disabled the firewall since I configured the FOG machine. It’s inactive.

dnsmasq seems to be running:

ps aux|grep dnsmasq
dnsmasq    66328  0.0  0.0  25232  3912 ?        Ss   15:10   0:00 /usr/sbin/dnsmasq -k

netstat -an | grep :67
udp        0      0 0.0.0.0:67              0.0.0.0:*

It seems to me that the switch won’t relay anything to the FOG machine. I’ve also tested all this with and without options 66 & 67 set on the dhcp server.

@george1421

Yes, my test client is on the same subnet (192.168.230.0/24). It is a virtual machine. I also have physical computer in the same subnet, that I’m using to examine frames with Wireshark.

My dnsmasq is running on the fog server, but my test virtual machine won’t pxe boot. In Wireshark there’s only two discover packets and one REQUEST coming from the VM. Seems like my FOG machine isn’t involved at all! Maybe after all it could be issue with the switch.

@george1421

Hey George. Thank you so much for taking the time to assist me!
I’ve configured dnsmasq as per your guide, but unfortunately it makes no difference. Bootprelay is enabled and pointing at the dnsmasq server (which is the same machine as the FOG server). My client is receiving IP address from the pool, but afterwards I’m getting “Nothing to boot” message and can’t proceed. My dnsmasq seems to be correct.

@george1421

I really wanted to utilize our switch (if possible). As I have already tested this with isc-dhcp server and I know it works.
So far I’ve option codes 66 and 67 on the switch. Also enabled BOOTPRELAY to the FOG server, but still no joy. Do you believe setting up dnsmasq could help me, or should I just stick to the isc-dhcp server?

edit: I have also tried setting option 67 to “http://192.168.230.51/fog/service/ipxe/boot.php” and that works, but loads the FOG menu without the fancy graphics

@george1421 said in "Please enter tftp server:" with single dhcp server:

@xcess said in "Please enter tftp server:" with single dhcp server:

DHCP Option Code 67 : string “tftp://192.168.xxx.xx/undionly.kpxe”

^^ This value is wrong ^^, just enter undionly.kpxe for bios based computers and ipxe.efi for uefi based computers.

Greetings, George. Initially I tried with what you’re suggesting but it didn’t work. Then the maintainer of iPXE suggested using the whole address with tftp url and that provided result.

@george1421 said in "Please enter tftp server:" with single dhcp server:

@xcess said in "Please enter tftp server:" with single dhcp server:

Server host name not given
Boot file name not given

This will be a problem too. That should align up with dhcp options 66 and 67.

So now to the question, what is your dhcp server (mfg/model)?

I’m using the built-in dhcp server on a ExtremeNetworks switch.

I know this might be annoying because I’m not the first one with the problem. I’ve read the other topics but unfortunately still can’t resolve my issue.
The setup is:

• FOG server running on Fedora
• dhcp server running on ExtremeNetworks core-switch.
• everything is running in a VLAN dedicated for testing purposes. No other DHCP servers.
• switch supports dhcp options codes, so I’ve set the following:
  • DHCP Option Code 66 : string “192.168.xxx.xx”
  • DHCP Option Code 67 : string “tftp://192.168.xxx.xx/undionly.kpxe”

Client boots into “Please enter tftp server:”
Providing the IP works.
I’ve investigated what’s going on with Wireshark and can confirm that there’s only one DHCP server messing around.
Here’s a snipped of a bootp frame:

Frame 106: 369 bytes on wire (2952 bits), 369 bytes captured (2952 bits) on interface \Device\NPF_{4C63F991-A548-48B3-A772-5278B943AE7F}, id 0
Ethernet II, Src: ExtremeN_9b:8e:d0 (00:04:96:9b:8e:d0), Dst: Broadcast (ff:ff:ff:ff:ff:ff)
Internet Protocol Version 4, Src: 192.168.230.253, Dst: 255.255.255.255
User Datagram Protocol, Src Port: 67, Dst Port: 68
Dynamic Host Configuration Protocol (Offer)
    Message type: Boot Reply (2)
    Hardware type: Ethernet (0x01)
    Hardware address length: 6
    Hops: 0
    Transaction ID: 0x811fa173
    Seconds elapsed: 0
    Bootp flags: 0x8000, Broadcast flag (Broadcast)
    Client IP address: 0.0.0.0
    Your (client) IP address: 192.168.230.200
    Next server IP address: 0.0.0.0
    Relay agent IP address: 0.0.0.0
    Client MAC address: 82:5d:c6:8a:7e:48 (82:5d:c6:8a:7e:48)
    Client hardware address padding: 00000000000000000000
    Server host name not given
    Boot file name not given
    Magic cookie: DHCP
    Option: (51) IP Address Lease Time
    Option: (53) DHCP Message Type (Offer)
    Option: (1) Subnet Mask (255.255.255.0)
    Option: (54) DHCP Server Identifier (192.168.230.253)
    Option: (3) Router
    Option: (6) Domain Name Server
    Option: (66) TFTP Server Name
        Length: 14
        TFTP Server Name: 192.168.xxx.xx
    Option: (67) Bootfile name
        Length: 35
        Bootfile name: tftp://192.168.xxx.xx/undionly.kpxe
    Option: (255) End

Aaand it seems that I’m stuck. Any help will be appreciated.