DHCP PXE configuration on multiple LANs - wrong filename (Bug?)

[naughtydog]

Hello,

something strange is happening over here.

I have an PXE Server running on subnet 10.91.0.0/24 (IP 10.91.0.1) which i use to serve PXE on multiple LANs.

For testing is use different boot filenames on each LAN.

LAN 10.91.0.0/24

LAN 10.94.0.0/24

"Additional BOOTP/DHCP Options" is empty on both LANs.

After booting up a Client on 10.91.0.0/24 i wondered why he received "undionly.kkpxe" instead of "ipxe.efi". I did a packet capture and indeed, the DHCP Server sends the wrong file.

0.0.0.0.68 > 255.255.255.255.67: [udp sum ok] BOOTP/DHCP, Request from ea:75:25:77:f1:7e, length 359, xid 0x81068654, Flags [Broadcast] (0x8000)
  Client-Ethernet-Address ea:75:25:77:f1:7e
  Vendor-rfc1048 Extensions
    Magic Cookie 0x63825363
    DHCP-Message Option 53, length 1: Request
    Server-ID Option 54, length 4: 10.91.0.253
    Requested-IP Option 50, length 4: 10.91.0.169
    MSZ Option 57, length 2: 65280
    Parameter-Request Option 55, length 35: 
      Subnet-Mask, Time-Zone, Default-Gateway, Time-Server
      IEN-Name-Server, Domain-Name-Server, Hostname, BS
      Domain-Name, RP, EP, RSZ
      TTL, BR, YD, YS
      NTP, Vendor-Option, Requested-IP, Lease-Time
      Server-ID, RN, RB, Vendor-Class
      TFTP, BF, GUID, Option 128
      Option 129, Option 130, Option 131, Option 132
      Option 133, Option 134, Option 135
    GUID Option 97, length 17: 0.206.73.168.108.53.9.185.72.128.118.176.75.127.225.187.247
    NDI Option 94, length 3: 1.3.1
    ARCH Option 93, length 2: 7
    Vendor-Class Option 60, length 32: "PXEClient:Arch:00007:UNDI:003001"

10.91.0.252.67 > 255.255.255.255.68: [udp sum ok] BOOTP/DHCP, Reply, length 306, xid 0x81068654, Flags [Broadcast] (0x8000)
  Your-IP 10.91.0.169
  Server-IP 10.91.0.1
  Client-Ethernet-Address ea:75:25:77:f1:7e
  file "undionly.kkpxe"
  Vendor-rfc1048 Extensions
    Magic Cookie 0x63825363
    DHCP-Message Option 53, length 1: ACK
    Server-ID Option 54, length 4: 10.91.0.252
    Lease-Time Option 51, length 4: 6155
    Subnet-Mask Option 1, length 4: 255.255.255.0
    Default-Gateway Option 3, length 4: 10.91.0.254
    Domain-Name-Server Option 6, length 8: 10.0.1.1,10.0.1.2
    Domain-Name Option 15, length 9: "net.intra"
    NTP Option 42, length 4: 10.91.0.254
    TFTP Option 66, length 9: "10.91.0.1"

In the DHCP configuration file i found this:

subnet 10.94.0.0 netmask 255.255.255.0 {
    pool {
            option domain-name-servers 10.0.1.1,10.0.1.2;
            deny dynamic bootp clients;
            failover peer "dhcp_opt77";

            range 10.94.0.1 10.94.0.200;
    }

    option routers 10.94.0.254;
    option domain-name "net.intra";
    option domain-name-servers 10.0.1.1,10.0.1.2;
    ping-check true;
    option ntp-servers 10.94.0.254;
    option tftp-server-name "10.91.0.1";

    next-server 10.91.0.1;
    if option arch = 00:06 {
            filename "snponly.efi";
    } else if option arch = 00:07 {
            filename "snponly.efi";
    } else if option arch = 00:09 {
            filename "snponly.efi";
    } else {
            filename "undionly.kkpxe";
    }

}

subnet 10.91.0.0 netmask 255.255.255.0 {
    pool {
            option domain-name-servers 10.0.1.1,10.0.1.2;
            deny dynamic bootp clients;
            failover peer "dhcp_opt19";

            filename "undionly.kkpxe";
            range 10.91.0.100 10.91.0.200;
    }

    option routers 10.91.0.254;
    option domain-name "net.intra";
    option domain-name-servers 10.0.1.1,10.0.1.2;
    ping-check true;
    option ntp-servers 10.91.0.254;
    option tftp-server-name "10.91.0.1";

    next-server 10.91.0.1;
    if option arch = 00:06 {
            filename "ipxe.efi";
    } else if option arch = 00:07 {
            filename "ipxe.efi";
    } else if option arch = 00:09 {
            filename "ipxe.efi";
    } else {
            filename "ipxe.efi";
    }

}

"subnet 10.91.0.0" wrongly contains filename "undionly.kkpxe";, which belongs to "subnet 10.94.0.0"

Looks like a bug to me.