[Differential] D10485: Replace dhcp option 150 by 66

Wed May 3 06:53:15 UTC 2017

tsoome added a comment.

  btw, I did test with my vmware fusion VM, the pxe boot is sending out:
  DHCP: Message type = DHCPDISCOVER
  DHCP: Requested Options:
  DHCP:    1 (Subnet Mask)
  DHCP:    2 (UTC Time Offset)
  DHCP:    3 (Router)
  DHCP:    5 (IEN 116 Name Servers)
  DHCP:    6 (DNS Servers)
  DHCP:   11 (RFC 887 Resource Location Servers)
  DHCP:   12 (Client Hostname)
  DHCP:   13 (Boot File size in 512 byte Blocks)
  DHCP:   15 (DNS Domain Name)
  DHCP:   16 (SWAP Server)
  DHCP:   17 (Client Root Path)
  DHCP:   18 (BOOTP options extensions path)
  DHCP:   43 (Vendor Specific Options)
  DHCP:   54 (DHCP Server Identifier)
  DHCP:   60 (Client Class Identifier =)
  DHCP:   67 (Simple Mail (SMTP) Servers)
  DHCP:   128 (Site Option)
  DHCP:   129 (Site Option)
  DHCP:   130 (Site Option)
  DHCP:   131 (Site Option)
  DHCP:   132 (Site Option)
  DHCP:   133 (Site Option)
  DHCP:   134 (Site Option)
  DHCP:   135 (Site Option)
  DHCP: Maximum DHCP Message Size = 1260 bytes
  DHCP: Unrecognized Option = 97, length = 17 octets
  DHCP:   Value = 0x00 0x56 0x4D 0xED 0x79 0xDF 0xA9 0x40 0xE1 0x61 0xAC 0x8F 0x85 0x11 0x7B 0xF5 0x59 (unprintable)
  DHCP: Unrecognized Option = 93, length = 2 octets
  DHCP:   Value = 0x00 0x00 (unprintable)
  DHCP: Unrecognized Option = 94, length = 3 octets
  DHCP:   Value = 0x01 0x02 0x01 (unprintable)
  DHCP: Client Class Identifier = "PXEClient:Arch:00000:UNDI:002001"

  So, no 66, 150 from this one. Also, I did check with isc-dhcp 4.3.4, this one does not offer options which are *not* asked for.

  And this means that if we do not want to rely on root path syntax, and if we want to have configurable (by dhcp server config) tftp-nfs selection, we can not rely on pxe reply and we have to build the proper option list and request them, thus leaving the PXE response as is (it is for the boot file loading anyhow).

  Yes, there may be an client asking for an option 66 as seen above, but there are also ones *not* asking, and the sad thing is, you have no way to tell if the 66 was asked for but the admin does not set it in dhcp config as the NFS is wanted, or 66 was not asked by PXE, but we would like to have TFTP boot.

REVISION DETAIL
  https://reviews.freebsd.org/D10485

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To: kczekirda, bapt, oshogbo, tsoome, sbruno, #network, freebsd-net-list, imp, jhb
Cc: rgrimes, garga, ler, asomers