Ethernet frame is a OSI data link layer (layer 2) protocol data unit for Ethernet networks. In practice, many other networks and/or in-file dumps adopted the same format for encapsulation purposes.
This page hosts a formal specification of Ethernet frame (layer 2, IEEE 802.3) using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.
All parsing code for Python generated by Kaitai Struct depends on the Python runtime library. You have to install it before you can parse data.
The Python runtime library can be installed from PyPI:
python3 -m pip install kaitaistructParse a local file and get structure in memory:
data = EthernetFrame.from_file("path/to/local/file.bin")
Or parse structure from a bytes:
from kaitaistruct import KaitaiStream, BytesIO
raw = b"\x00\x01\x02..."
data = EthernetFrame(KaitaiStream(BytesIO(raw)))
After that, one can get various attributes from the structure by invoking getter methods like:
data.dst_mac # => Destination MAC address
data.ether_type # => Ether type can be specied in several places in the frame. If
first location bears special marker (0x8100), then it is not the
real ether frame yet, an additional payload (`tci`) is expected
and real ether type is upcoming next.
# This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild
import kaitaistruct
from kaitaistruct import KaitaiStruct, KaitaiStream, BytesIO
from enum import Enum
if getattr(kaitaistruct, 'API_VERSION', (0, 9)) < (0, 9):
raise Exception("Incompatible Kaitai Struct Python API: 0.9 or later is required, but you have %s" % (kaitaistruct.__version__))
import ipv4_packet
import ipv6_packet
class EthernetFrame(KaitaiStruct):
"""Ethernet frame is a OSI data link layer (layer 2) protocol data unit
for Ethernet networks. In practice, many other networks and/or
in-file dumps adopted the same format for encapsulation purposes.
.. seealso::
Source - https://ieeexplore.ieee.org/document/7428776
"""
class EtherTypeEnum(Enum):
ipv4 = 2048
x_75_internet = 2049
nbs_internet = 2050
ecma_internet = 2051
chaosnet = 2052
x_25_level_3 = 2053
arp = 2054
ieee_802_1q_tpid = 33024
ipv6 = 34525
def __init__(self, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
def _read(self):
self.dst_mac = self._io.read_bytes(6)
self.src_mac = self._io.read_bytes(6)
self.ether_type_1 = KaitaiStream.resolve_enum(EthernetFrame.EtherTypeEnum, self._io.read_u2be())
if self.ether_type_1 == EthernetFrame.EtherTypeEnum.ieee_802_1q_tpid:
self.tci = EthernetFrame.TagControlInfo(self._io, self, self._root)
if self.ether_type_1 == EthernetFrame.EtherTypeEnum.ieee_802_1q_tpid:
self.ether_type_2 = KaitaiStream.resolve_enum(EthernetFrame.EtherTypeEnum, self._io.read_u2be())
_on = self.ether_type
if _on == EthernetFrame.EtherTypeEnum.ipv4:
self._raw_body = self._io.read_bytes_full()
_io__raw_body = KaitaiStream(BytesIO(self._raw_body))
self.body = ipv4_packet.Ipv4Packet(_io__raw_body)
elif _on == EthernetFrame.EtherTypeEnum.ipv6:
self._raw_body = self._io.read_bytes_full()
_io__raw_body = KaitaiStream(BytesIO(self._raw_body))
self.body = ipv6_packet.Ipv6Packet(_io__raw_body)
else:
self.body = self._io.read_bytes_full()
class TagControlInfo(KaitaiStruct):
"""Tag Control Information (TCI) is an extension of IEEE 802.1Q to
support VLANs on normal IEEE 802.3 Ethernet network.
"""
def __init__(self, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
def _read(self):
self.priority = self._io.read_bits_int_be(3)
self.drop_eligible = self._io.read_bits_int_be(1) != 0
self.vlan_id = self._io.read_bits_int_be(12)
@property
def ether_type(self):
"""Ether type can be specied in several places in the frame. If
first location bears special marker (0x8100), then it is not the
real ether frame yet, an additional payload (`tci`) is expected
and real ether type is upcoming next.
"""
if hasattr(self, '_m_ether_type'):
return self._m_ether_type
self._m_ether_type = (self.ether_type_2 if self.ether_type_1 == EthernetFrame.EtherTypeEnum.ieee_802_1q_tpid else self.ether_type_1)
return getattr(self, '_m_ether_type', None)