DHCP

[treiher]

Schemas

• Fixed-size field systematization-binary-schemas#1
• Field length defined by available space systematization-binary-schemas#3 (options)
• Field type: unsigned integer with restricted value range systematization-binary-schemas#12 (flags)
• Optional field (occurrence determined by available space) systematization-binary-schemas#14 (options)
• Field type: unsigned integer systematization-binary-schemas#20 (xid, secs)
• Field type: signed integer systematization-binary-schemas#21 (options: time offset)
• Field type: enumeration systematization-binary-schemas#22 (op, htype, hlen, options: code)
• Field type: ASCII string systematization-binary-schemas#25 (sname, file)
• Sequence length defined by available space systematization-binary-schemas#30 (options)
• Field type: constant systematization-binary-schemas#41 (options)

The first four octets of the 'options' field of the DHCP message
contain the (decimal) values 99, 130, 83 and 99, respectively (this
is the same magic cookie as is defined in RFC 1497 [17]).

• Invariant over sequence elements systematization-binary-schemas#34 (options)

the "DHCP message type" option - must be included in every DHCP
message. This option defines the "type" of the DHCP message.
Additional options may be allowed, required, or not allowed,
depending on the DHCP message type.

• Non-contiguous field systematization-binary-schemas#56 (options, sname, file)

Option Overload

This option is used to indicate that the DHCP "sname" or "file"
fields are being overloaded by using them to carry DHCP options. A
DHCP server inserts this option if the returned parameters will
exceed the usual space allotted for options.

If this option is present, the client interprets the specified
additional fields after it concludes interpretation of the standard
option fields.

Specification

https://tools.ietf.org/html/rfc2131