NDIS - Part 1

  • Article

Hi, my name Anurag Sarin, I am an escalation engineer in the Platforms Global Escalation Team. I would like to give some insight on NDIS.

NDIS Introduction

The Network Driver Interface Specification (NDIS) library abstracts the network hardware from network drivers. NDIS also specifies a standard interface between layered network drivers, thereby abstracting lower-level drivers that manage hardware from upper-level drivers, such as network transports. NDIS also maintains state information and parameters for network drivers, including pointers to functions, handles, and parameter blocks for linkage, and other system values.

Types of network drivers

  • Miniport drivers
  • Intermediate drivers
  • Filter drivers
  • Protocol drivers

ndiskd is a good extension for debugging NDIS drivers .The document Debugging NDIS Drivers  has more information about ndiskd.

To get a list of NDIS protocols drivers in the system, the protocols option in ndiskd can be used.

This also gives a list of all NDIS open blocks on each protocol driver. Protocol open block is described in the later section.

 

A Protocol Driver is represented by a NDIS Protocol Block, which is shown as Protocol below:

 

1: kd> !ndiskd.protocols

 Protocol 8ef57590: NDISUIO

    Open 8ef61860 - Miniport: 902bbab0 X Network Team #1

 Protocol 8f3aea50: TCPIP_WANARP

    Open 8f3ae508 - Miniport: 90287ae8 WAN Miniport (IP)

 Protocol 8f220008: TCPIP

    Open 8f21d210 - Miniport: 902bbab0 X Network Team #1

 Protocol 9029bbf8: NDPROXY

    Open 901618e0 - Miniport: 9019f130 Direct Parallel

    Open 90161c80 - Miniport: 9019f130 Direct Parallel

    Open 9018bcd0 - Miniport: 901ba130 WAN Miniport (L2TP)

    Open 90171490 - Miniport: 901ba130 WAN Miniport (L2TP)

 Protocol 901e3008: RASPPPOE

 Protocol 901bb008: NDISWAN

    Open 90216b30 - Miniport: 9019f130 Direct Parallel

    Open 9047e518 - Miniport: 901fdab0 WAN Miniport (PPTP)

    Open 90198c20 - Miniport: 90276ab0 WAN Miniport (PPPOE)

    Open 901989e0 - Miniport: 901ba130 WAN Miniport (L2TP)

 Protocol 902de6e0: Y_TEAM

    Open 9028ef10 - Miniport: 9029b5e8 P Gigabit Server Adapter #2

    Open 90198b10 - Miniport: 9029eab0 Q Multifunction Gigabit Server Adapter #2

 

NDIS filter drivers are represented by Filter Driver Block (s) shown below.

0: kd> !ndiskd.filters

NDIS Driver verifier level: 0

NDIS Failed allocations : 0

Filter Driver Block: 97412e58

  Filter: 97414c10 Z Network Connection-Native WiFi Filter Driver-0000

    Miniport 85d160e8 Z Network Connection

Filter Driver Block: 8797bdb0

  Filter: 97446c10 Z Network Connection - H Miniport-QoS Packet Scheduler-0000

    Miniport 8610b0e8 Z Network Connection - H Miniport

  Filter: 87b1b730 Y Network Adapter - H Miniport-QoS Packet Scheduler-0000

    Miniport 8611c0e8 Y Network Adapter - H Miniport

  Filter: 879c3008 G Network Connection - H Miniport-QoS Packet Scheduler-0000

    Miniport 861150e8 G Network Connection - H Miniport

  Filter: 879c0a50 WAN Miniport (IP) - H Miniport-QoS Packet Scheduler-0000

    Miniport 861240e8 WAN Miniport (IP) - H Miniport

  Filter: 879bb3f8 WAN Miniport (IPv6) - H Miniport-QoS Packet Scheduler-0000

    Miniport 861250e8 WAN Miniport (IPv6) - H Miniport

  Filter: 87981870 WAN Miniport (Network Monitor) - H Miniport-QoS Packet Scheduler-0000

    Miniport 861260e8 WAN Miniport (Network Monitor) - H Miniport

  Filter: 8797f518 Nortel IPSECSHM Adapter - H Miniport-QoS Packet Scheduler-0000

    Miniport 861170e8 Nortel IPSECSHM Adapter - H Miniport

 

The “miniports” option lists all NDIS miniport drivers represented by a Miniport Driver Block (s).

kd> !ndiskd.miniports

NDIS Driver verifier level: 0

NDIS Failed allocations : 0

Miniport Driver Block: 885915b8, Version 0.0

  Miniport: 8863a0e8, NetLuidIndex: 1, IfIndex: 7, RAS Async Adapter

Miniport Driver Block: 88018010, Version 0.0

  Miniport: 8828d488, NetLuidIndex: 1, IfIndex: 3, WAN Miniport (PPTP)

Miniport Driver Block: 87e535a8, Version 0.0

  Miniport: 88150200, NetLuidIndex: 0, IfIndex: 4, WAN Miniport (PPPOE)

Miniport Driver Block: 87f63510, Version 0.0

  Miniport: 880ac4b8, NetLuidIndex: 0, IfIndex: 5, WAN Miniport (IPv6)

  Miniport: 880844c0, NetLuidIndex: 3, IfIndex: 6, WAN Miniport (IP)

Miniport Driver Block: 87f2ccb8, Version 0.0

  Miniport: 88091488, NetLuidIndex: 0, IfIndex: 2, WAN Miniport (L2TP)

Miniport Driver Block: 8809de60, Version 10.1

  Miniport: 883bf0e8, NetLuidIndex: 10, IfIndex: 15, MY PCI Fast Ethernet Adapter (Emulated) #4

  Miniport: 883be0e8, NetLuidIndex: 5, IfIndex: 11, MY PCI Fast Ethernet Adapter (Emulated) #3

  Miniport: 883bd0e8, NetLuidIndex: 6, IfIndex: 9, MY PCI Fast Ethernet Adapter (Emulated) #2

  Miniport: 883bc0e8, NetLuidIndex: 4, IfIndex: 8, MY PCI Fast Ethernet Adapter (Emulated)

Miniport Driver Block: 87f77df0, Version 1.0

  Miniport: 87f9c488, NetLuidIndex: 6, IfIndex: 16, isatap.{584AF5A9-63C2-44C5-970D-DB85057F2931}

  Miniport: 87f75488, NetLuidIndex: 4, IfIndex: 14, isatap.fareast.corp.microsoft.com

  Miniport: 87fc6488, NetLuidIndex: 3, IfIndex: 10, isatap.{CCDB4297-B958-4C2A-95A5-29150BD0A371}

 

The interfaces option lists all Network interfaces

kd> !ndiskd.interfaces

Interface block 87fb12a8

<Snip>

  IfIndex: 20, IfType: 6

Inerface Guid: 5d0bd81a-47c7-11dc-a9d2-0003ff2b6bfa

Interface block 88101ab0

  IfIndex: 21, IfType: 6

Inerface Guid: ed1c50d5-ff1f-11db-9b85-0003ff7133d2

Interface block 87f82ab0

  IfIndex: 15, IfType: 6

Inerface Guid: f442c036-8bf5-43a6-91fd-6792ef752100

Interface block 881cd5d8

  IfIndex: 22, IfType: 6

Inerface Guid: ed1c50d4-ff1f-11db-9b85-9459bf825974

Interface block 87f313f8

<Snip>

 

 Interface guids correspond to each network interface. Some interfaces have their information in the in the registry .For Example on my machine Interface Guid: f442c036-8bf5-43a6-91fd-6792ef752100 corresponds to registry:-

 

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces\{F442C036-8BF5-43A6-91FD-6792EF752100}

 

NDIS Driver Stack

Basic Stack Configuration

 

The MSDN web page NDIS Driver Stack  has basic documentation on the NDIS stack

 

For Miniport details, the miniport option can be used.

kd> !ndiskd.miniport 883bc0e8

 Miniport 883bc0e8 : MY PCI Fast Ethernet Adapter (Emulated), v5.0

    AdapterContext : 8809e000

    Flags : 2c412008

                     BUS_MASTER, IGNORE_TOKEN_RING_ERRORS, RESOURCES_AVAILABLE

                     SUPPORTS_MEDIA_SENSE, DOES_NOT_DO_LOOPBACK, MEDIA_CONNECTED

    PnPFlags : 80210000

                     RECEIVED_START, HARDWARE_DEVICE,

    MiniportState : STATE_RUNNING

    IfIndex : 8

    Ndis5MiniportInNdis6Mode : 1

    InternalResetCount : 0000

    MiniportResetCount : 0000

    References : 5

    UserModeOpenReferences: 0

    PnPDeviceState : PNP_DEVICE_STARTED

    CurrentDevicePowerState : PowerDeviceD0

    Bus PM capabilities

       DeviceD1: 0

       DeviceD2: 0

       WakeFromD0: 0

       WakeFromD1: 0

       WakeFromD2: 0

       WakeFromD3: 0

       SystemState DeviceState

       PowerSystemUnspecified PowerDeviceUnspecified

       S0 D0

       S1 PowerDeviceUnspecified

       S2 PowerDeviceUnspecified

       S3 PowerDeviceUnspecified

       S4 D3

       S5 D3

       SystemWake: PowerSystemUnspecified

       DeviceWake: PowerDeviceUnspecified

    Current PnP and PM Settings: : 00000030

                     DISABLE_WAKE_UP, DISABLE_WAKE_ON_RECONNECT,

    Translated Allocated Resources:

        IO Port: 0000e480, Length: 80

        Memory: febfc000, Length: 1000

     Interrupt Level: 10, Vector: 3b

    MediaType : 802.3

    DeviceObject : 883bc030, PhysDO : 87ca1030 Next DO: 87ca1030

    MapRegisters : 00000000

    FirstPendingPkt: 00000000

    DriverVerifyFlags : 00000000

    Miniport Interrupt : 8809e008

    Miniport version 5.0

    Miniport Filter List:

 Filter 88301c28: FilterDriver 88129300, FilterModuleContext 880d7230 MY PCI Fast Ethernet Adapter (Emulated)-QoS Packet Scheduler-0000

    Miniport Open Block Queue:

      88263278: Protocol 88300830 = RSPNDR, ProtocolBindingContext 87fb7820, v6.0

      882446d0: Protocol 8835a300 = LLTDIO, ProtocolBindingContext 88323310, v6.0

      880d2c58: Protocol 8831e2e0 = TCPIP, ProtocolBindingContext 88329008, v6.0

 

Current PnP capacities and Power Management Settings are shown by flags and can be one of these values in the Current PnP and PM Settings’ section.

 

NOT_STOPPABLE : The device is not stoppable i.e. ISA

NOT_REMOVEABLE : The device cannot be safely removed

NOT_SUSPENDABLE : The device cannot be safely suspended

DISABLE_PM : Disable all Power Management features

DISABLE_WAKE_UP : Disable device waking up the system .This is evident when the user disables Wake-On-LAN (WOL)  feature on the miniport adaptor

DISABLE_WAKE_ON_RECONNECT: Disable device waking up the -system- due to a cable re-connect

 

Above , the miniport block 883bc0e8 represents MY PCI Fast Ethernet Adapter, i.e. the NIC driver on my machine. The NIC driver has a binding with filter driver MY PCI Fast Ethernet Adapter (Emulated)-QoS Packet Scheduler and protocols drivers RSPNDR, LLTDIO and TCPIP.

 

                   The stack with the debug output above would look somewhat like this.

To see what all miniport drivers the Protocol driver has bound to - the protocol option can be used.

kd> !protocol 8831e2e0

 Protocol 8831e2e0 : TCPIP

 RootDeviceName is \DEVICE\{B4982B71-0255-4D04-A585-4C339162A25D}

 v6.0 RefCount 5

    Open 880d2c58 - Miniport: 883bc0e8 Intel 21140-Based PCI Fast Ethernet Adapter (Emulated)

    Open 881bbc58 - Miniport: 883bd0e8 Intel 21140-Based PCI Fast Ethernet Adapter (Emulated) #2

    Open 881bcc58 - Miniport: 883be0e8 Intel 21140-Based PCI Fast Ethernet Adapter (Emulated) #3

    Open 881c0c58 - Miniport: 883bf0e8 Intel 21140-Based PCI Fast Ethernet Adapter (Emulated) #4

 BindAdapterHandlerEx 8e93da28, UnbindAdapterHandlerEx 8e9d7a87

 PnPEventHandler 8e933b83, UnloadHandler 00000000

 OpenAdapterCompleteEx 8e9d74ff, CloseAdapterCompleteEx 8e9d7722

 SendNetBufferListsCompleteHandler 8e997067, ReceiveNetBufferListsHandler 8e98ff5f

 StatusComplete 00000000, StatusHandler 8e942cad

 AssociatedMiniDriver 00000000

      Flags : 00000000

This also shows the various handler routines of the Protocol TCPIP Driver routines.

Un-assembling the routines would verify them further.

kd> u 8e93da28

tcpip!FlBindAdapter:

8e93da28 8bff mov edi,edi

8e93da2a 55 push ebp

8e93da2b 8bec mov ebp,esp

8e93da2d 83ec1c sub esp,1Ch

8e93da30 53 push ebx

8e93da31 56 push esi

8e93da32 57 push edi

8e93da33 6a06 push 6

kd> u 8e933b83

tcpip!Fl48PnpEvent:

8e933b83 8bff mov edi,edi

8e933b85 55 push ebp

8e933b86 8bec mov ebp,esp

8e933b88 837d0800 cmp dword ptr [ebp+8],0

8e933b8c 7406 je tcpip!Fl48PnpEvent+0x11 (8e933b94)

8e933b8e 5d pop ebp

8e933b8f e96c030000 jmp tcpip!FlPnpEvent (8e933f00)

8e933b94 8b450c mov eax,dword ptr [ebp+0Ch]

 

NDIS Open Block is a block that represents the binding between a Miniport Driver and a Protocol Driver. So there is one NDIS Open Block per binding between a protocol and a miniport.

kd> !ndiskd.opens

  Open 885283c0

    Miniport: 8863a0e8 - RAS Async Adapter

    Protocol: 8803be48 -

  Open 88263278

    Miniport: 883bc0e8 - MY PCI Fast Ethernet Adapter (Emulated)

    Protocol: 88300830 - RSPNDR

  Open 88263628

    Miniport: 883bd0e8 - MY PCI Fast Ethernet Adapter (Emulated) #2

    Protocol: 88300830 - RSPNDR

  Open 88124008

    Miniport: 883be0e8 - MY PCI Fast Ethernet Adapter (Emulated) #3

    Protocol: 88300830 - RSPNDR

  Open 883276a0

    Miniport: 883bf0e8 - MY PCI Fast Ethernet Adapter (Emulated) #4

    Protocol: 88300830 - RSPNDR

  Open 882446d0

    Miniport: 883bc0e8 - MY PCI Fast Ethernet Adapter (Emulated)

    Protocol: 8835a300 - LLTDIO

  Open 882fa398

    Miniport: 883bd0e8 - MY PCI Fast Ethernet Adapter (Emulated) #2

    Protocol: 8835a300 - LLTDIO

  Open 882d5550

    Miniport: 883be0e8 - MY PCI Fast Ethernet Adapter (Emulated) #3

    Protocol: 8835a300 - LLTDIO

  Open 882cf470

    Miniport: 883bf0e8 - MY PCI Fast Ethernet Adapter (Emulated) #4

    Protocol: 8835a300 - LLTDIO

  Open 88219968

    Miniport: 880ac4b8 - WAN Miniport (IPv6)

    Protocol: 880f04a0 - WANARPV6

  Open 8816e008

    Miniport: 880844c0 - WAN Miniport (IP)

    Protocol: 882e5008 - WANARP

  Open 881eec58

    Miniport: 883bd0e8 - MY PCI Fast Ethernet Adapter (Emulated) #2

    Protocol: 88383138 - TCPIP6

  Open 881b6c58

  Miniport: 883be0e8 - MY PCI Fast Ethernet Adapter (Emulated) #3

    Protocol: 88383138 - TCPIP6

  Open 880d2c58

    Miniport: 883bc0e8 - MY PCI Fast Ethernet Adapter (Emulated)

    Protocol: 8831e2e0 - TCPIP

  Open 881bbc58

    Miniport: 883bd0e8 - MY PCI Fast Ethernet Adapter (Emulated) #2

    Protocol: 8831e2e0 - TCPIP

  Open 881c2c58

    Miniport: 883bf0e8 - MY PCI Fast Ethernet Adapter (Emulated) #4

    Protocol: 88383138 - TCPIP6

  Open 881bcc58

    Miniport: 883be0e8 - MY PCI Fast Ethernet Adapter (Emulated) #3

    Protocol: 8831e2e0 - TCPIP

  Open 881c0c58

    Miniport: 883bf0e8 - MY PCI Fast Ethernet Adapter (Emulated) #4

    Protocol: 8831e2e0 - TCPIP

  Open 8811a6a0

    Miniport: 87fbb0e8 - isatap.{B4982B71-0255-4D04-A585-4C339162A25D}

    Protocol: 882d8298 - TCPIP6TUNNEL

  Open 8811a008

    Miniport: 87fc6488 - isatap.{CCDB4297-B958-4C2A-95A5-29150BD0A371}

    Protocol: 882d8298 - TCPIP6TUNNEL

  Open 881f8870

    Miniport: 87f75488 - isatap.fareast.corp.microsoft.com

    Protocol: 882d8298 - TCPIP6TUNNEL

  Open 882a4850

    Miniport: 87f9c488 - isatap.{584AF5A9-63C2-44C5-970D-DB85057F2931}

    Protocol: 882d8298 - TCPIP6TUNNEL

   Open 881ad960

    Miniport: 8828d488 - WAN Miniport (PPTP)

    Protocol: 8803be48 -

   Open 88018c58

    Miniport: 88150200 - WAN Miniport (PPPOE)

    Protocol: 8803be48 -

   Open 8831f818

    Miniport: 88091488 - WAN Miniport (L2TP)

    Protocol: 87f1e100 -

   Open 8831fc10

    Miniport: 88091488 - WAN Miniport (L2TP)

    Protocol: 87f1e100 -

   Open 881425a8

    Miniport: 88091488 - WAN Miniport (L2TP)

    Protocol: 8803be48 -

Use mopen option to see the details of the NDIS Open Block.

kd> !mopen 881bbc58

 Miniport Open Block 881bbc58

    Protocol 8831e2e0 = TCPIP, ProtocolContext 88348008, v6.0

    Miniport 883bd0e8 = MY PCI Fast Ethernet Adapter (Emulated) #2, v5.0

    MiniportAdapterContext: 880a1000

    Flags : 01000000

                     OPEN_USE_MULTICAST_LIST,

    References : 1

The ‘References’ section above shows the number of outstanding Input Output Requests. This can be use full to investigate how many requests by a protocol driver are passed to the next lower driver which are currently outstanding.

Network Data

Network data consists of packets of data that are sent or received over the network. NDIS provides data structures to describe and organize such data. The primary NDIS 6.0 network data structures include the following:

· NET_BUFFER structures

· NET_BUFFER LIST structures

· NET_BUFFER_LIST_CONTEXT structures

For NDIS 5.x we have NDIS PACKETS in place of NET_BUFFER structure.

NDIS_PACKET Structure

NDIS packets (represented by a NDIS_PACKET  structure) are allocated by a protocol driver, filled with data, and passed to the next lower NDIS driver so that the data can be sent on the network. Some lowest level NIC drivers allocate packets to hold received data and pass the packet up to interested higher-layer drivers. Sometimes, a protocol driver allocates a packet and passes it to a NIC driver with a request that the NIC driver copy received data into the provided packet. NDIS provides functions for allocating and manipulating the substructures that make up a packet. The following figure illustrates a structure of a packet.

Each NDIS Packet is basically a Packet Descriptor. Each Packet Descriptor has a series of Buffer Descriptors.

A packet is composed of the following:

  • A packet descriptor that contains private areas for the miniport driver and a protocol driver, a set of flags associated with the packet and whose meaning is defined by a cooperating miniport driver(s) and protocol driver(s), the number of physical pages that contain the packet, the total length of the packet, and a pointer to the first buffer descriptor that maps the first buffer in the packet.
  • A set of buffer descriptors. A buffer descriptor describes the starting virtual address of each buffer, the buffer's byte offset into the page pointed to by the virtual address, the total number of bytes in the buffer and a pointer to the next buffer descriptor, if any.
  • The virtual range, possibly spanning more than one page that makes up the buffer described by the buffer descriptor. These virtual pages map to physical memory.

The pkt option in ndiskd helps us to see the contents of the NDIS Packet. It has various verbose options:

Usage: pkt <pointer to packet> <verbosity>

<verbosity> can be between 1 to 5.

1-Packet Private

2-Packet Extension

3-Ndis Reference

 4-Buffer List

5- Data in Packet List

1: kd> !ndiskd.pkt 0x8f3aabf8

NDIS_PACKET at 8f3aabf8

Packet.Private

  PhysicalCount 00000001 Total Length 00000036

  Head 8f3aa630 Tail 8a667d30

  Pool 90331d20 Count 00000001

  Flags 00000002 ValidCounts 01

  NdisPacketFlags 00000000 NdisPacketOobOffset 006c

      Private.Flags : 00000002

      Private.NdisPacketFlags: 0

 

Above output indicates a typical Packet Descriptor.

 

Below is a description of the fields in above output.

 

PhysicalCount : Number of physical pages in packet.

TotalLength    : Total amount of data in the packet in bytes.

Head                    : First buffer in the chain. If Head is NULL the chain is empty.

Tail                    : Last buffer in the chain.

Count                 : The number of Buffers in the chain.

ValidCounts   : Represent a Boolean value on validity of the Counts.

Pool                  : NDIS Packet Pool address so we know where to free it back to.

To demonstrate what an NDIS packet looks like, a breakpoint was placed on routine NdisMSendComplete. The definition of NdisMSendComplete states that ‘PNDIS_PACKET Packet’ is the second parameter. So the address of NDIS Packet can be found at EBP+0xC position on the stack.

 kd> kvn

 # ChildEBP RetAddr Args to Child

00 818f1c44 8b8848c3 883be0e8 88727538 00000000 ndis!NdisMSendComplete+0x10 (FPO: [Non-Fpo])

01 818f1c7c 8b884b2f 8817d280 81827c97 00000000 dc21x4vm!ProcessTransmitDescRing+0x363 (FPO: [Non-Fpo])

02 818f1c9c 81718cb1 00010005 88166008 883be0e8 dc21x4vm!DC21X4HandleInterrupt+0xfb (FPO: [Non-Fpo])

03 818f1cc8 81682d1f 8816601c 88166008 00000000 ndis!ndisMDpc+0x16b (FPO: [Non-Fpo])

04 818f1ce8 818a93ae 8816601c 88166008 00000000 ndis!ndis5InterruptDpc+0x9c (FPO: [Non-Fpo])

05 818f1d50 818912ae 00000000 0000000e 00000000 nt!KiRetireDpcList+0x147

06 818f1d54 00000000 0000000e 00000000 00000000 nt!KiIdleLoop+0x46 (FPO: [0,0,0])

You can use verbosity 4 for looking at the Buffer Descriptors anda pointer to the next buffer descriptor, if any as shown below.

ndis.h available with Windows Driver Kit (WDK) orWindows Driver Device Kit (DDK) has definition for NdisPacketFlags

The verbosity 5 as most interesting - the NDIS packet data contents are displayed.

kd> !pkt poi(@ebp+c) 5

NDIS_PACKET at 88727538

       MDL = 886f3ca0

              StartVa ffffffff886f3000, ByteCount 0x36, ByteOffset 0xd06, NB MdlOffset 0x0

       886f3d06: 00 13 5f 0b ef ca 00 15 5d 50 f3 34 08 00 45 00

       886f3d16: 03 23 04 44 40 00 80 06 ce 2e 41 34 50 de 41 34

       886f3d26: 52 1c c0 51 00 50 6d f9 e6 c2 9a 14 d4 99 50 18

       886f3d36: 40 29 0e e5 00 00

              MDL = 87f3aad0

              StartVa ffffffff886f4000, ByteCount 0x2fb, ByteOffset 0x40, NB MdlOffset 0x0

       886f4040: 47 45 54 20 68 74 74 70 3a 2f 2f 77 77 77 2e 6d

       886f4050: 73 6e 2e 63 6f 6d 2f 61 6a 61 78 2f 48 2e 61 73

       886f4060: 70 78 20 48 54 54 50 2f 31 2e 31 0d 0a 41 63 63

       886f4070: 65 70 74 3a 20 2a 2f 2a 0d 0a 41 63 63 65 70 74

       886f4080: 2d 4c 61 6e 67 75 61 67 65 3a 20 65 6e 2d 75 73

       886f4090: 0d 0a 52 65 66 65 72 65 72 3a 20 68 74 74 70 3a

       886f40a0: 2f 2f 77 77 77 2e 6d 73 6e 2e 63 6f 6d 2f 0d 0a

       886f40b0: 55 41 2d 43 50 55 3a 20 78 38 36 0d 0a 41 63 63

       886f40c0: 65 70 74 2d 45 6e 63 6f 64 69 6e 67 3a 20 67 7a

       886f40d0: 69 70 2c 20 64 65 66 6c 61 74 65 0d 0a 55 73 65

       886f40e0: 72 2d 41 67 65 6e 74 3a 20 4d 6f 7a 69 6c 6c 61

       886f40f0: 2f 34 2e 30 20 28 63 6f 6d 70 61 74 69 62 6c 65

       886f4100: 3b 20 4d 53 49 45 20 37 2e 30 3b 20 57 69 6e 64

       886f4110: 6f 77 73 20 4e 54 20 36 2e 30 3b 20 53 4c 43 43

       886f4120: 31 3b 20 2e 4e 45 54 20 43 4c 52 20 32 2e 30 2e

       886f4130: 35 30 37 32 37 3b 20 2e 4e 45 54 20 43 4c 52 20

       886f4140: 33 2e 30 2e 30 34 35 30 36 29 0d 0a 48 6f 73 74

       886f4150: 3a 20 77 77 77 2e 6d 73 6e 2e 63 6f 6d 0d 0a 50

       886f4160: 72 6f 78 79 2d 43 6f 6e 6e 65 63 74 69 6f 6e 3a

       886f4170: 20 4b 65 65 70 2d 41 6c 69 76 65 0d 0a 43 6f 6f

       886f4180: 6b 69 65 3a 20 4d 43 31 3d 56 3d 33 26 47 55 49

       886f4190: 44 3d 31 61 31 61 65 64 38 31 38 36 34 30 34 32

       886f41a0: 39 62 61 63 32 37 38 61 65 37 65 39 63 38 35 39

       886f41b0: 64 39 3b 20 6d 68 3d 4d 53 46 54 3b 20 43 55 4c

       886f41c0: 54 55 52 45 3d 45 4e 2d 55 53 3b 20 4d 55 49 44

       886f41d0: 3d 32 43 38 33 35 42 36 32 34 35 42 46 34 46 30

       886f41e0: 36 38 36 36 43 34 37 38 38 42 46 39 30 43 35 38

       886f41f0: 32 3b 20 7a 69 70 3d 7a 3a 45 43 31 7c 6c 61 3a

       886f4200: 35 31 2e 35 31 32 32 32 31 38 38 7c 6c 6f 3a 30

       886f4210: 7c 63 3a 47 42 7c 68 72 3a 31 3b 20 46 6c 69 67

       886f4220: 68 74 47 72 6f 75 70 49 64 3d 34 37 3b 20 46 6c

       886f4230: 69 67 68 74 49 64 3d 42 61 73 65 50 61 67 65 3b

       886f4240: 20 75 73 68 70 73 76 72 3d 4d 3a 35 7c 46 3a 35

       886f4250: 7c 54 3a 35 7c 45 3a 35 7c 44 3a 62 6c 75 7c 57

       886f4260: 3a 46 7c 50 3a 4e 7c 56 3a 30 3b 20 75 73 68 70

       886f4270: 63 6c 69 3d 30 7c 48 2e 30 2e 31 7c 47 2e 30 2e

       886f4280: 31 7c 5a 2e 30 2e 31 7c 52 2e 30 2e 31 2e 63 61

       886f4290: 70 7c 43 2e 30 2e 31 2e 6c 67 3a 6e 65 77 79 6f

       886f42a0: 72 6b 6e 79 7c 4c 2e 30 2e 31 2e 4c 4e 3a 57 4e

       886f42b0: 42 43 3b 20 75 73 68 70 77 65 61 3d 77 63 3a 55

       886f42c0: 53 4e 59 30 39 39 36 3b 20 75 73 68 70 70 72 3d

       886f42d0: 43 3a 31 3a 30 38 30 37 32 31 7c 53 3a 31 3a 30

       886f42e0: 38 30 38 30 36 3b 20 68 70 63 6c 69 3d 57 2e 48

       886f42f0: 7c 4c 2e 7c 53 2e 7c 52 2e 7c 55 2e 4c 7c 43 2e

       886f4300: 3b 20 68 70 73 76 72 3d 4d 3a 35 7c 46 3a 35 7c

       886f4310: 54 3a 35 7c 45 3a 35 7c 44 3a 62 6c 75 7c 57 3a

       886f4320: 46 3b 20 68 70 6f 6c 79 3d 4f 3a 31 7c 48 3a 31

       886f4330: 3b 20 77 70 76 3d 30 0d 0a 0d 0a

Above output shows starting virtual address of each buffer, the buffer's byte offset into the page pointed to by the virtual address and the total number of bytes in the buffer

 

Looking at the contents of the memory buffer closely :-

 

kd> dc 886f4040 886f4330+0xc

886f4040 20544547 70747468 772f2f3a 6d2e7777 GET https://www.m

886f4050 632e6e73 612f6d6f 2f78616a 73612e48 sn.com/ajax/H.as

886f4060 48207870 2f505454 0d312e31 6363410a px HTTP/1.1..Acc

886f4070 3a747065 2a2f2a20 63410a0d 74706563 ept: */*..Accept

886f4080 6e614c2d 67617567 65203a65 73752d6e -Language: en-us

886f4090 65520a0d 65726566 68203a72 3a707474 ..Referer: http:

886f40a0 77772f2f 736d2e77 6f632e6e 0a0d2f6d //www.msn.com/..

886f40b0 432d4155 203a5550 0d363878 6363410a UA-CPU: x86..Acc

886f40c0 2d747065 6f636e45 676e6964 7a67203a ept-Encoding: gz

886f40d0 202c7069 6c666564 0d657461 6573550a ip, deflate..Use

886f40e0 67412d72 3a746e65 7a6f4d20 616c6c69 r-Agent: Mozilla

886f40f0 302e342f 6f632820 7461706d 656c6269 /4.0 (compatible

886f4100 534d203b 37204549 203b302e 646e6957 ; MSIE 7.0; Wind

886f4110  2073776f 3620544e 203b302e 43434c53 ows NT 6.0; SLCC

886f4120 2e203b31 2054454e 20524c43 2e302e32 1; .NET CLR 2.0.

886f4130 32373035 2e203b37 2054454e 20524c43 50727; .NET CLR

886f4140 2e302e33 30353430 0a0d2936 74736f48 3.0.04506)..Host

886f4150 7777203a 736d2e77 6f632e6e 500a0d6d : www.msn.com..P

886f4160 79786f72 6e6f432d 7463656e 3a6e6f69 roxy-Connection:

886f4170 65654b20 6c412d70 0d657669 6f6f430a Keep-Alive..Coo

886f4180 3a65696b 31434d20 333d563d 49554726 kie: MC1=V=3&GUI

886f4190 61313d44 64656131 36383138 32343034 D=1a1aed81864042

886f41a0 63616239 61383732 39653765 39353863 9bac278ae7e9c859

886f41b0 203b3964 4d3d686d 3b544653 4c554320 d9; mh=MSFT; CUL

886f41c0 45525554 2d4e453d 203b5355 4449554d TURE=EN-US; MUID

886f41d0 3843323d 36423533 42353432 30463446 =2C835B6245BF4F0

886f41e0 36363836 38373443 39464238 38354330 6866C4788BF90C58

886f41f0 7a203b32 7a3d7069 3143453a 3a616c7c 2; zip=z:EC1|la:

886f4200 352e3135 32323231 7c383831 303a6f6c 51.51222188|lo:0

886f4210 473a637c 72687c42 203b313a 67696c46 |c:GB|hr:1; Flig

886f4220 72477468 4970756f 37343d64 6c46203b htGroupId=47; Fl

886f4230 74686769 423d6449 50657361 3b656761 ightId=BasePage;

886f4240 68737520 72767370 353a4d3d 353a467c ushpsvr=M:5|F:5

886f4250 353a547c 353a457c 623a447c 577c756c |T:5|E:5|D:blu|W

886f4260 507c463a 567c4e3a 203b303a 70687375 :F|P:N|V:0; ushp

886f4270 3d696c63 2e487c30 7c312e30 2e302e47 cli=0|H.0.1|G.0.

886f4280 2e5a7c31 7c312e30 2e302e52 61632e31 1|Z.0.1|R.0.1.ca

886f4290 2e437c70 2e312e30 6e3a676c 6f797765 p|C.0.1.lg:newyo

886f42a0 796e6b72 302e4c7c 4c2e312e 4e573a4e rkny|L.0.1.LN:WN

886f42b0 203b4342 70687375 3d616577 553a6377 BC; ushpwea=wc:U

886f42c0 30594e53 3b363939 68737520 3d727070 SNY0996; ushppr=

886f42d0 3a313a43 37303830 537c3132 303a313a C:1:080721|S:1:0

886f42e0 30383038 68203b36 696c6370 482e573d 80806; hpcli=W.H

886f42f0 7c2e4c7c 527c2e53 2e557c2e 2e437c4c |L.|S.|R.|U.L|C.

886f4300 7068203b 3d727673 7c353a4d 7c353a46 ; hpsvr=M:5|F:5|

886f4310 7c353a54 7c353a45 6c623a44 3a577c75 T:5|E:5|D:blu|W:

886f4320 68203b46 796c6f70 313a4f3d 313a487c F; hpoly=O:1|H:1

886f4330 7077203b 0d303d76 2e0a0d0a 2e6e736d ; wpv=0.....msn.

 

So this packets contains HTTP traffic for MSN ! (Very true I had the msn site open while I was debugging this machineJ).

 

 A list all NDIS packet pools can be displayed with the pktpools option, each pool would have set of NDIS packets.

kd> !pktpools

Pool Allocator BlocksAllocated BlockSize PktsPerBlock PacketLength

87faa268 8b88d1a1 0x6 0x1000 0x13 0xd0 dc21x4vm!AllocateAdapterMemory+16b

87f6f4e0 8b88d1a1 0x6 0x1000 0x13 0xd0 dc21x4vm!AllocateAdapterMemory+16b

87fbf2f0 8b88d1a1 0x6 0x1000 0x13 0xd0 dc21x4vm!AllocateAdapterMemory+16b

87f4eb40 8b88d1a1 0x6 0x1000 0x13 0xd0 dc21x4vm!AllocateAdapterMemory+16b

87e19620 8174d66c 0x1 0x1000 0x12 0xd8 ndis!DriverEntry+43d

87e19670  8174d65a 0x1 0x1000 0x13 0xd0 ndis!DriverEntry+42b

 

 A list of the NDIS packets in a packet pool can be displayed with the findpacket option. The pool address 87e19670 was obtained from the pktpools output above.

 

kd> !findpacket p 87e19670

Searching Free block <0x88727000>

Packet at 0x88727538

0x88727538 is our http packet shown above.

 

Another variant of findpacket is used to find an NDIS packet with a Virtual address from the packet buffer. A random address 886f4110 was obtained from the packet buffer above with http contents.

kd> !findpacket v 886f4110

Searching Free block <0x881a3000>

Searching Used block <0x88185000>

Searching Used block <0x88187000>

Searching Used block <0x8818b000>

Searching Used block <0x8818f000>

Searching Used block <0x88193000>

Searching Free block <0x88176000>

<Snip>

Searching Free block <0x88727000>

Packet found

Packet at 0x88727538

Packet.Private

  PhysicalCount 00000000 Total Length 00000000

  Head 00000000 Tail 00000000

  Pool 00000000 Count 00000000

  Flags 00000000 ValidCounts 00

  NdisPacketFlags 00000000 NdisPacketOobOffset 0000

      Private.Flags : 00000082

                     DONT_LOOPBACK,

      Private.NdisPacketFlags: 90

                     fPACKET_PENDING, fPACKET_CLEAR_ITEMS, fPACKET_ALLOCATED_BY_NDIS

 

I hope this gives the reader a better understanding of NDIS stacks.