DHCPv4 (`dhcpv4`)

Layer: Application and control
Header: variable length
Notes: Application protocols

Reached from

Lower layer	Selector	Value
`udp`	`dst_port` / `src_port`	67 (0x0043)
`udp`	`dst_port` / `src_port`	68 (0x0044)

Fields

Field	Type	Default	Auto	Description
`op`	`enum(8)`	`1` (boot_request)		BOOTP message op code (1 = BOOTREQUEST, 2 = BOOTREPLY).
`htype`	`uint(8)`	`1`		Hardware address type (1 = Ethernet).
`hlen`	`uint(8)`	`6`		Hardware address length, in octets (6 for Ethernet).
`hops`	`uint(8)`	`0`		Relay hop count, incremented by each relay agent.
`xid`	`uint(32)`	`305419896`		Transaction ID chosen by the client.
`secs`	`uint(16)`	`0`		Seconds elapsed since the client began acquisition.
`flags`	`flags(16)`	`0x0`		BOOTP flags (bit 15 = broadcast reply requested).
`ciaddr`	`ipv4`	`0.0.0.0`		Client IP address (when already bound).
`yiaddr`	`ipv4`	`0.0.0.0`		“Your” (client) IP address assigned by the server.
`siaddr`	`ipv4`	`0.0.0.0`		Next server IP address (boot server).
`giaddr`	`ipv4`	`0.0.0.0`		Relay agent (gateway) IP address; non-zero when relayed.
`chaddr`	`mac`	`02:00:00:00:00:01`		Client hardware (MAC) address; followed by 10 octets of padding.
`chaddr_padding`	`bytes(10)`	`00 00 00 00 00 00 00 00 00 00`
`sname`	`bytes(64)`	`00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00`		Optional server host name (64 octets, NUL padded).
`file`	`bytes(128)`	`00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00`		Boot file name (128 octets, NUL padded).
`magic_cookie`	`uint(32)`	`1669485411`		DHCP magic cookie (0x63825363).
`options`	`tlv` — rest of the PDU	2 items		DHCP options (8-bit code / length; Pad, End, Message Type, Relay Agent Information, …).

`op`

Value	Name
1 (0x01)	`boot_request`
2 (0x02)	`boot_reply`

`flags`

Bit	Mask	Name
15	32768 (0x8000)	`broadcast`

`options`

Type 8 bits, length 8 bits.
The length counts the value only.
Unknown types are kept as raw value octets.

Type	Name	Value fields	Description
0 (0x00)	`pad`	(type only, no length or value)
1 (0x01)	`subnet_mask`	`mask`
3 (0x03)	`router`	`addresses`
6 (0x06)	`dns_servers`	`addresses`
12 (0x0c)	`host_name`
15 (0x0f)	`domain_name`
50 (0x32)	`requested_ip`	`address`
51 (0x33)	`lease_time`	`seconds`
53 (0x35)	`message_type`	`type`
54 (0x36)	`server_id`	`address`
55 (0x37)	`parameter_request_list`	`codes`
58 (0x3a)	`renewal_time`	`seconds`
59 (0x3b)	`rebinding_time`	`seconds`
61 (0x3d)	`client_id`
82 (0x52)	`relay_agent_info`	`suboptions`
255 (0xff)	`end`	(type only, no length or value)

`options` › `subnet_mask`

Field	Type	Default	Auto	Description
`mask`	`ipv4`

`options` › `router`

Field	Type	Default	Auto	Description
`addresses`	`list<ipv4>` — rest of the PDU

`options` › `dns_servers`

Field	Type	Default	Auto	Description
`addresses`	`list<ipv4>` — rest of the PDU

`options` › `requested_ip`

Field	Type	Default	Auto	Description
`address`	`ipv4`

`options` › `lease_time`

Field	Type	Default	Auto	Description
`seconds`	`uint(32)`

`options` › `message_type`

Field	Type	Default	Auto	Description
`type`	`enum(8)`

`options` › `message_type` › `type`

Value	Name
1 (0x01)	`discover`
2 (0x02)	`offer`
3 (0x03)	`request`
4 (0x04)	`decline`
5 (0x05)	`ack`
6 (0x06)	`nak`
7 (0x07)	`release`
8 (0x08)	`inform`

`options` › `server_id`

Field	Type	Default	Auto	Description
`address`	`ipv4`

`options` › `parameter_request_list`

Field	Type	Default	Auto	Description
`codes`	`list<uint(8)>` — rest of the PDU

`options` › `renewal_time`

Field	Type	Default	Auto	Description
`seconds`	`uint(32)`

`options` › `rebinding_time`

Field	Type	Default	Auto	Description
`seconds`	`uint(32)`

`options` › `relay_agent_info`

Field	Type	Default	Auto	Description
`suboptions`	`tlv` — rest of the PDU

`options` › `relay_agent_info` › `suboptions`

Type 8 bits, length 8 bits.
The length counts the value only.
Unknown types are kept as raw value octets.

Type	Name	Value fields	Description
1 (0x01)	`circuit_id`
2 (0x02)	`remote_id`
5 (0x05)	`link_selection`	`address`
11 (0x0b)	`server_id_override`	`address`

`options` › `relay_agent_info` › `suboptions` › `link_selection`

Field	Type	Default	Auto	Description
`address`	`ipv4`

`options` › `relay_agent_info` › `suboptions` › `server_id_override`

Field	Type	Default	Auto	Description
`address`	`ipv4`

Constraints

Level	Rule
warning	`magic_cookie` = 1669485411

Sample templates

dhcpv4-discover — templates/protocols/app/dhcpv4-discover.wpg.yaml
dhcpv4-relay — templates/protocols/app/dhcpv4-relay.wpg.yaml
scenario-dhcp-discover-flood — templates/scenarios/dhcp-discover-flood.wpg.yaml