AH - Authentication Header¶

pcapkit.protocols.internet.ah contains AH only, which implements extractor for Authentication Header (AH) [*], whose structure is described as below:

Octets	Bits	Name	Description
0	0	`ah.next`	Next Header
1	8	`ah.length`	Payload Length
2	16		Reserved (must be zero)
4	32	`sah.spi`	Security Parameters Index (SPI)
8	64	`sah.seq`	Sequence Number Field
12	96	`sah.icv`	Integrity Check Value (ICV)

class pcapkit.protocols.internet.ah.AH(file=None, length=None, **kwargs)[source]¶

Bases: IPsec[AH, AH]

This class implements Authentication Header.

property name: Literal['Authentication Header']¶: Name of corresponding protocol.

property length: int¶: Header length of current protocol.

property payload: ProtocolBase | NoReturn¶

Payload of current instance.

Raises:: UnsupportedCall – if the protocol is used as an IPv6 extension header

property protocol: str | None | NoReturn¶

Name of next layer protocol (if any).

Raises:: UnsupportedCall – if the protocol is used as an IPv6 extension header

property protochain: ProtoChain | NoReturn¶

Protocol chain of current instance.

Raises:: UnsupportedCall – if the protocol is used as an IPv6 extension header

classmethod id()[source]¶

Index ID of the protocol.

Return type:: tuple[Literal['AH']]
Returns:: Index ID of the protocol.

read(length=None, *, version=4, extension=False, **kwargs)[source]¶

Read Authentication Header.

Structure of AH header [RFC 4302]:

 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header   |  Payload Len  |          RESERVED             |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                 Security Parameters Index (SPI)               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                    Sequence Number Field                      |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                                                               |
+                Integrity Check Value-ICV (variable)           |
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Parameters:

length (Optional[int]) – Length of packet data.
version (Literal[4, 6]) – IP protocol version.
extension (bool) – If the protocol is used as an IPv6 extension header.
**kwargs (Any) – Arbitrary keyword arguments.

Return type:

AH

Returns:

Parsed packet data.

make(next=<TransType.UDP: 17>, next_default=None, next_namespace=None, next_reversed=False, spi=0, seq=0, icv=b'', payload=b'', **kwargs)[source]¶

Make (construct) packet data.

Parameters:

next (TransType | IntEnum | IntEnum | str | int) – Next header type.
next_default (Optional[int]) – Default value of next header type.
next_namespace (Union[dict[str, int], dict[int, str], Type[IntEnum], Type[IntEnum], None]) – Namespace of next header type.
next_reversed (bool) – If the namespace is reversed.
spi (int) – Security Parameters Index.
seq (int) – Sequence Number Field.
icv (bytes) – Integrity Check Value-ICV.
payload (bytes | ProtocolBase | Schema) – Payload of current instance.
**kwargs (Any) – Arbitrary keyword arguments.

Return type:

AH

Returns:

Constructed packet data.

classmethod _make_data(data)[source]¶

Create key-value pairs from data for protocol construction.

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

__post_init__(file=None, length=None, *, version=4, extension=False, **kwargs)[source]¶

Post initialisation hook.

Parameters:

file (Union[IO[bytes], bytes, None]) – Source packet stream.
length (Optional[int]) – Length of packet data.
version (Literal[4, 6]) – IP protocol version.
extension (bool) – If the protocol is used as an IPv6 extension header.
**kwargs (Any) – Arbitrary keyword arguments.

Return type:

None

Header Schemas¶

class pcapkit.protocols.schema.internet.ah.AH(dict_=None, **kwargs)[source]¶

Bases: Schema

Header schema for AH packet.

next: Enum_TransType = <EnumField next>¶: Next header.

len: int = <UInt8Field len>¶: Payload length.

reserved: bytes = <PaddingField reserved>¶: Reserved.

spi: int = <UInt32Field spi>¶: Security parameters index.

seq: int = <UInt32Field seq>¶: Sequence number field.

icv: bytes = <BytesField icv>¶: Integrity check value.

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

Data Models¶

class pcapkit.protocols.data.internet.ah.AH(*args: VT, **kwargs: VT)[source]¶

Bases: Protocol

Data model for AH protocol.

next: TransType¶: Next header.

length: int¶: Payload length.

spi: int¶: Security parameters index.

seq: int¶: Sequence number field.

icv: bytes¶: Integrity check value.

Footnotes