Ethernet Protocol¶

pcapkit.protocols.link.ethernet contains Ethernet only, which implements extractor for Ethernet Protocol [*], whose structure is described as below:

Octets	Bits	Name	Description
0	0	`eth.dst`	Destination MAC Address
1	8	`eth.src`	Source MAC Address
2	16	`eth.type`	Protocol (Internet Layer)

class pcapkit.protocols.link.ethernet.Ethernet(file=None, length=None, **kwargs)[source]¶

Bases: Link[Ethernet, Ethernet]

This class implements Ethernet Protocol.

property name: Literal['Ethernet Protocol']¶: Name of current protocol.

property length: Literal[14]¶: Header length of current protocol.

property protocol: EtherType¶: Name of next layer protocol.

property src: str¶: Source mac address.

property dst: str¶: Destination mac address.

read(length=None, **kwargs)[source]¶

Read Ethernet Protocol.

Structure of Ethernet header [RFC 7042]:

 0                   1                   2                   3
 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                         Dst MAC Addr                          |
+                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                               |                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
|                         Src MAC Addr                          |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|          Ether Type           |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Parameters:

length (int | None) – Length of packet data.
**kwargs (Any) – Arbitrary keyword arguments.

Return type:

Ethernet

Returns:

Parsed packet data.

make(dst='00:00:00:00:00:00', src='00:00:00:00:00:00', type=<EtherType.Internet_Protocol_version_4: 2048>, type_default=None, type_namespace=None, type_reversed=False, payload=b'', **kwargs)[source]¶

Make (construct) packet data.

Parameters:

dst (str | bytes | bytearray) – Destination MAC address.
src (str | bytes | bytearray) – Source MAC address.
type (EtherType | IntEnum | IntEnum | str | int) – EtherType.
type_default (int | None) – Default EtherType.
type_namespace (dict[str, int] | dict[int, str] | Type[IntEnum] | Type[IntEnum] | None) – EtherType namespace.
type_reversed (bool) – Whether EtherType is reversed.
payload (bytes | ProtocolBase | Schema) – Payload data.
**kwargs (Any) – Arbitrary keyword arguments.

Return type:

Ethernet

Returns:

Constructed packet data.

classmethod _make_data(data)[source]¶

Create key-value pairs from data for protocol construction.

Parameters:: data (Ethernet) – protocol data
Return type:: dict[str, Any]
Returns:: Key-value pairs for protocol construction.

classmethod __index__()[source]¶

Numeral registry index of the protocol.

Return type:: LinkType
Returns:: Numeral registry index of the protocol in tcpdump link-layer header types.

Header Schemas¶

class pcapkit.protocols.schema.link.ethernet.Ethernet(*args: _VT, **kwargs: _VT)[source]¶

Bases: Schema

Header schema for ethernet packet.

dst: bytes = <BytesField dst>¶: Destination MAC address.

src: bytes = <BytesField src>¶: Source MAC address.

type: EtherType = <EnumField type>¶: Protocol (internet layer).

payload: bytes = <PayloadField payload>¶: Payload.

Auxiliary Functions¶

pcapkit.protocols.schema.link.ethernet.callback_payload(self, packet)[source]¶

Callback function for Ethernet.payload.

Parameters:

self (PayloadField) – Payload field to resolve.
packet (dict[str, Any]) – Packet data, whose type names the next layer.

Returns:

None; the resolved class is assigned to self.protocol.

Important

The lookup goes through ProtocolBase._lookup_next_layer rather than subscripting the registry. Ethernet.__proto__ is Link.__proto__, a class-level collections.defaultdict, so reading a missing key inserted it – every unregistered EtherType a parse saw was recorded as though somebody had registered it, and Link.register afterwards reported it as an overwrite. The helper reads the fallback without recording it, and memoises a ModuleDescriptor for a code that really is registered, which this did not.

Data Models¶

class pcapkit.protocols.data.link.ethernet.Ethernet(*args: VT, **kwargs: VT)[source]¶

Bases: Protocol

Data model for ethernet packet.

dst: str¶: Destination MAC address.

src: str¶: Source MAC address.

type: EtherType¶: Protocol (internet layer).

Footnotes