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Npcap 1.60 [2021-12-06]

  • Npcap can now tolerate network disconnections or NDIS stack modifications that previously resulted in programs like Wireshark stopping with the error "PacketReceivePacket error: The device has been removed. (1617)". This error may still be returned, but user programs can consider it a transient error. If the network is reconnected, capture can resume on the same handle. Fixes #506.

  • Improved validation for IRP parameters, resolving potential BSoD crashes that could be triggered by software interacting directly with the driver's device interface. These bugs still affect the last releases of WinPcap. Thanks to Ilja Van Sprundel from IOActive for reporting them.

  • Fix an issue with NX pool compatibility that caused Npcap 1.50 and 1.55 to fail to run on some Windows 7 systems. Fixes #536.

  • Fix how the installer handles /option=enforced, which was broken in Npcap 1.55. Fixes #556.

  • Concurrently released the Npcap SDK Version 1.12, which fixes native ARM compilation by including the ARM64 wpcap.lib, among other changes. The SDK now has its own change log at

  • Further driver source code hardening to catch more bugs before they manifest in worse ways. This includes adding more SAL annotations for code analysis, extra assertions, etc.

  • The /prior_driver installer option now selects the Npcap 1.30 driver, since Microsoft's cross-certificate expired 30 minutes before we signed Version 1.31. See #536.

  • Simplified the code base by removing a bunch of unused or unneccessary code. This includes "kernel dump mode" (MODE_DUMP) which was inherited from WinPcap 3.1 even though it had already been deactivated there in 2005. Also removed legacy WinPcap code which allowed their (long discontinued) "Pro" version DLL to install the driver itself. This is not allowed by modern operating systems. We were able to remove a bunch of code from NPFInstall.exe too. Updated the INF file to prevent npf_wifi service from being configured, since it was never actually used.

  • Fix an issue causing pcap_setmode()/PacketSetMode() with a value of MODE_CAPT to fail. MODE_CAPT is the default for new handles, so this only affects software that uses MODE_STAT and then switches to MODE_CAPT, or software that expects a call to pcap_setmode(MODE_CAPT) on a handle already in MODE_CAPT to succeed. Fixes #558.

  • When installing Npcap in WinPcap API-Compatible mode (the default), the Npcap installer will perform the uninstallation of WinPcap directly instead of running the WinPcap uninstaller. This prevents the WinPcap uninstaller from rebooting the system and allows us to clean up partial or broken installations.

  • Further deprecate the "Legacy loopback support" option: The npcapwatchdog scheduled task will not check for the existence of the Npcap Loopback Adapter.

  • Added the PnpLockDown directive to the npcap.sys INF file for additional Windows file protection of the driver binary.

  • Replaced a feature of NPFInstall.exe and the SimpleSC.dll NSIS plugin with Powershell commands to improve installer size and compatibility. May fix #226.

  • While you won't see it in the code itself, we dramatically improved our automated build and testing proceses. We now run automated native-arch builds and testing of multiple programs (particularly the SDK Examples) on all 3 architectures (x86, x64, and ARM). All tests are run with the debug build of the driver (assertions on) and Driver Verifier with at least standard settings, and only when that passes is the release build run through the same tests, also with Driver Verifier. The tests are also run in x86 emulation on x64 and ARM.

Npcap 1.55 [2021-09-03]

  • Npcap installer can now recognize NetCfg status codes indicating that a reboot is required (0x0004a020, NETCFG_S_REBOOT), and will prompt the user to reboot. In silent mode, the installer will return code 3010 (0x0bc2, ERROR_SUCCESS_REBOOT_REQUIRED) to indicate this result. Fixes #224.

  • The silent installer (only available in Nmap OEM) now offers better control over when to remove and reinstall an existing Npcap. You can specify your Npcap version number or feature requirements with the new /require_version, /require_features, and /force options. Software with strict requirements might re-run at startup to ensure that Npcap hasn't been uninstalled or changed. If Npcap still exists and meets your requirements, the installer quits immediately. These new options are documented at and Nmap OEM is described at Fixes #523.

  • Fixed an installation failure (0xe0000247) on Windows 8.1/Server 2012 R2 and earlier systems which have not updated root certificates. The root certificates are now installed to the Roots trust store. Fixes #233.

  • Fixed an issue since Npcap 1.30 where broadcast and subnet masks for adapters returned by pcap_findalldevs() were in host byte order, displaying values like "". Fixes #525.

  • Libpcap 1.10.1 has been updated to include some recent changes to the libpcap-1.10 release branch which extend support to adapters with the NdisMediumIP media type, including Wireguard Wintun virtual adapters. Fixes #173.

  • Added specific bad-value checks for issues originating in other drivers which may be incorrectly attributed to Npcap. These checks, in combination with additional const qualifiers, should serve as assurance that Npcap is not modifying traffic during capture and cannot be responsible for such crashes.

  • Powershell commands launched by the installer are now run with the -NoProfile option. Fixes #529.

  • Npcap SDK 1.11 released. This includes upstream libpcap changes to allow building with older Visual Studio versions, as well as minor changes to add const qualifiers to parameters to several Packet.dll functions. Fixes #518.

  • Npcap installer now uses Unicode internally. This may result in mixed-encoding install.log files.

Npcap 1.50 [2021-06-22]

  • Fixed #513 which prevented Npcap 1.40 from installing.

  • Npcap can now be installed on Windows 10 for ARM64 devices. Both ARM64 and x86 DLLs will be installed, allowing existing x86 applications such as Nmap or Wireshark to run without modification.

  • Npcap SDK 1.10 release coincides with this release, providing updated documentation and libs for ARM64.

  • Npcap code now passes Microsoft's Static Driver Verifier for NDIS drivers and Visual Studio's Code Analysis "AllRules" ruleset. A couple of minor and extremely-improbable bugs were fixed in addition to general code cleanup and annotation.

  • On Windows 8 and 8.1, the Npcap driver has been updated to NDIS 6.30, supporting network stack improvements like RSC and QoS. Windows 10 still uses NDIS 6.50 and Windows 7 uses NDIS 6.20.

  • Npcap is no longer distributed with SHA-1 digital signatures. Windows 7 and Server 2008 R2 will require KB4474419 in order to install Npcap. All other platforms support SHA-2 digital signatures by default.

  • Streamlined loopback packet injection to avoid using Winsock Kernel (WSK) sockets. This removes a significant amount of complexity and overhead.

  • Due to Microsoft's deprecation of cross-signed root certificates for kernel-mode code signing, Npcap 1.40 may not install correctly on Windows versions prior to Windows 10. Our testing did not show any issues, but users who experience installation failures may use the /prior_driver=yes installation option to install the Npcap 1.31 driver instead, which has no such issues.

  • The "npcapwatchdog" scheduled task, which ensures the Npcap driver service is configured to start at boot, is now installed with a description when possible (Windows 7 does not support creating scheduled tasks via PowerShell). Fixes #498.

  • All PowerShell scripts installed or used during installation are now digitally signed.

  • Fix an issue where installation under Citrix Remote Access or other situations would fail with the message "Installer runtime error 255 at 76539962, Could not load SimpleSC.dll". Fixes #226.

  • Ensure driver signature can be validated on systems without Internet access by installing the entire certificate chain, including the chain for the timestamp counter-signature. This should address #233.

  • Fix an issue with comparing adapter names retrieved from the Registry. This prevented Npcap 1.31 from being used for SendToRx and other less-used features. Fixes #311.

  • Npcap driver no longer excludes adapters based on media type, which may allow capture on some devices that were previously unavailable.

Npcap 1.40 [2021-06-21]

  • This release was retracted due to installer issues. See #513.

Npcap 1.31 [2021-04-21]

  • Fix a bug with the non-default legacy loopback capture support that caused all requests to open a capture handle to open the loopback capture instead. It is recommended to not select "Legacy loopback support" at installation unless you know your application relies on it. Fixes #302.

  • For Windows 10 and Server 2016 and later, restore the ability to capture traffic on VMware VMnet interfaces such as the host-only and NAT virtual networks. This will be restored for other supported Windows versions in a later release. Fixes #304.

Npcap 1.30 [2021-04-09]

  • Restore raw WiFi frame capture support, which had been broken in a few ways since Npcap 0.9983. Additional improvements enable PacketSetMonitorMode() for non-admin-privileged processes, allowing Wireshark to correctly enable monitor mode via checkbox without requiring WlanHelper.exe.

  • Fixed WlanHelper.exe to correctly set modes and channels for adapters, if run with Administrator privileges. Fixes #122.

  • Improved speed of pcap_findalldevs() by using fewer calls to GetAdaptersAddresses() and avoiding direct Registry inspection. The new method may result in more adapters being available for capture than previously reported. See #169.

  • Updated Packet.dll to use modern HeapAlloc() allocation, faster than the legacy GlobalAlloc() inherited from WinPcap.

  • Improve error reporting from PacketGetAdapterNames() and related functions.

Npcap 1.20 [2021-03-10]

  • Upgrade wpcap.dll to libpcap 1.10. This change enables software to use pcap_set_tstamp_type() to set the packet capture time source and precision per capture handle. The currently-supported types (see pcap-tstamp) are:

  • Fix an issue preventing WlanHelper.exe from changing WiFi parameters for adapters which caused the error message "makeOIDRequest::My_PacketOpenAdapter error". Fixes #122 and several other reports of the same issue.

  • Fixed an issue that prevented NDIS protocol drivers from reducing the hardware packet filter, even if the removed bits/filters were only set by that protocol driver initially. This caused network interruptions on VMware systems. Fixes #106.

  • Fixed an issue with pcap_sendqueue_transmit() that caused it to busy-wait in an attempt to synchronize packet sends with pcap timestamps, even when the program did not request synchronization. Fixes #113.

  • The installer will now safely remove and replace broken installations due to #268.

  • Upgraded installer to NSIS 3, which improves compatibility with modern Windows versions.

  • Added application manifests to several installer tools and removed Windows Vista from the manifests of others, improving compatibility.

Npcap 1.10 [2020-12-11]

  • Fixed an issue where our upgrade uninstaller would trigger the #1924 BSoD crash when upgrading from Npcap 0.9988 or older to version 0.9996 or greater. Fixes #268.

  • Improved handling of large packets when a very small user buffer size is specified, which could lead to stalled captures and dropped packets.

  • Fix a packet corruption issue when one capture handle sets a snaplen of exactly 256 bytes and another sets a snaplen of greater than 256 bytes and the packet size exceeds 256 bytes.

  • Fix accounting of free space in the kernel buffer so that bugs like the previous one do not cause space to be permanently lost, leading to dropped packets. Instead, use assertions to catch this condition in testing with the debug build.

  • Check that the npcap driver service is configured for SYSTEM_START in the npcapwatchdog scheduled task and correct it if necessary. Windows feature updates can modify this value.

Npcap 1.00 [2020-09-25]

  • After more than 7 years of development and 170 previous public releases, the Nmap Project is delighted to release Npcap version 1.00!

  • New Packet.dll function PacketGetTimestampModes() to retrieve supported packet timestamping modes. These do not currently vary by adapter, but TIMESTAMPMODE_QUERYSYSTEMTIME_PRECISE is not supported on Windows 7, for example. Fixes #174.

  • Npcap driver is now only signed with SHA256 signatures on platforms other than Windows 7, which may resolve signature validation issues on some systems. The Windows 7 driver is signed with SHA-1 signatures only.

Npcap 0.9997 [2020-08-25]

  • Fix an integer underflow in the amount of free buffer space available leading to excessive memory consumption. Fixes #223.

  • Significantly reduced per-packet memory overhead for packets in the kernel capture buffer.

  • Replaced object pool/slab allocator with Windows lookaside lists, improving performance by avoiding spinlocks and allowing the system to adjust memory consumption.

Npcap 0.9996 [2020-08-07]

  • Fix a runaway memory leak triggered by low-resources condition leading to system hangs. Fixes #213.

  • Fix a BSoD crash in NPF_Read in some high-traffic cases. Fixes #206.

  • Fix a handle leak in Packet.dll when enumerating interfaces. Fixes #26.

  • Fix an inconsistency between return value and IRP completion status in NPF_Read when an adapter is removed. Driver Verifier would cause a bugcheck (BSoD) in this case, and pcap API functions would not detect an error. Fixes #217

  • Improved performance by reusing allocated packet data buffers and implementing DISPATCH_LEVEL tracking throughout the driver to speed up lock acquisition.

  • When upgrading from compatible recent versions (currently Npcap 0.9985 and newer), the installer will unpack a new Uninstall.exe and NPFInstall.exe prior to removing the existing installation. This resolves issues with the uninstallation process such as were common in Npcap 0.9991 through 0.9994.

  • Upgraded build system to VisualStudio 2019 and WDK 10.0.18362.0

Npcap 0.9995 [2020-07-10]

  • Fix a BSoD crash in NPF_Read when NDIS filter module is detached from the adapter. Fixes #194

  • On Windows 10, the Npcap driver has been updated to NDIS 6.50 and Windows 10 WFP compatibility, supporting network stack improvements like RSC. Fixes #196.

  • Correctly obey maximum frame size for an adapter by querying OID_GEN_MAXIMUM_TOTAL_SIZE instead of using MTU, which does not include space for the link layer header. Fixes #186.

  • Fix detection of processes using Npcap resources during uninstall or upgrade. The fix for #2015 had broken this so such processes were not terminated, leading to failed installations.

  • Obey snaplen (pcap_set_snaplen()) even if a packet filter is not set. This is a backported change from upstream libpcap that corrects a deficiency that has been present in all previous versions of WinPcap and Npcap. Fixes #201.

  • Improvements to object pool/slab allocator to allow nonpaged memory to be freed when not in use.

  • When installing Npcap OEM in silent mode, avoid running C:\Uninstall.exe if no existing Npcap installation is present.

Npcap 0.9994 [2020-06-12]

  • Fix a BSoD crash in NPF_ReleaseOpenInstanceResources due to miscounting of number of open Loopback capture instances. Fixes #185.

  • Fix corrupted and missing packets in Npcap 0.9992 and 0.9993 due to reusing a data structure that already contained packet data.

  • Ensure our SHA-1 code signing certificate is also installed on systems which may require it. This was preventing installation on older platforms since Npcap 0.9991.

  • Fix a crash in NPFInstall.exe that happened when trying to rebind Npcap to the network stack as part of some installations. Reported by Microsoft App Assure ISV Outreach Team.

  • When multiple packets are indicated in a single FilterReceiveNetBufferLists callback, only get a single timestamp for all of them. Avoids extra calls to KeQueryPerformanceCounter or KeQuerySystemTimePrecise which only ended up measuring Npcap processing delay, not actual packet arrival time.

  • Fix a potential NULL pointer deref issue in Objpool.h macros if an allocation were to fail and return a NULL pointer.

  • Fix parsing of pnputil.exe output that resulted in Npcap drivers not being cleared from the DriverStore before installing or upgrading. This led to older drivers being preferred in some cases, such as installing an unsigned driver in test mode.

  • Move all capture- and injection-related initialization code out of NPF_OpenAdapter, improving efficiency of operations like listing adapters or performing OID requests without starting a full capture.

  • Added SAL annotations to most driver functions to improve static analysis. Found one issue related to using a NULL NDIS handle in an allocation function, which is not supported on Windows 7.

  • Allow driver to load even if there is a problem initializing loopback capture or injection functions. The loopback capture device will simply be unavailable in that case.

Npcap 0.9993 [2020-06-05]

  • Fix a BSoD crash in NPF_DoInternalRequest triggered by suspending the system while a capture is running. Added source annotations to allow static analysis to catch bugs like this in the future. Fixes #181.

  • Fix a bug introduced in Npcap 0.9992 which caused loopback capture to fail if any loopback capture had been previously started and finished.

  • Fix packet length calculation for loopback capture. The packet length was being counted twice, leading to junk data being appended to captured packets.

  • If installation fails for any reason other than a failure to uninstall the previous version of Npcap, the current version's uninstaller will be used to clean up any partial installation. The only remaining files will be the install.log and NPFInstall.log in the Npcap installation directory.

  • Replaced ReadWriteLock mechanisms with improved NDIS_RW_LOCK_EX new in NDIS 6.20 for improved performance.

  • Moved object pool for captured packets from the filter module (adapter) object to the open instance (pcap handle) to allow memory to be recovered after a capture is closed.

Npcap 0.9992 [2020-06-03]

  • Npcap issues are now tracked on their own Github Issues page, separate from Nmap issues. Many existing issues have been migrated, and issue numbers may have changed.

  • Rewrote the kernel packet capture buffer code again to avoid requiring a separate worker thread. Instead, captured packets are held directly in a synchronized queue. The worker thread introduced in Npcap 0.9991 was unable to keep up with the volume of packet requests, leading to buffer bloat and reduced performance.

  • Avoid initializing loopback capture-related functions and processing packets as soon as an adapter is opened. This will improve performance since adapters are opened as part of listing adapters.

  • Fix a crash in NPFInstall.exe when terminating processes which are using Npcap resources. This could lead to failed installations and message windows about "A LWF & WFP driver installation tool has stopped working."

  • Update Npcap from NDIS 6.10 to NDIS 6.20, which limits its compatibility to Windows 7 and higher. Closes #167.

  • Fix a bug in Npcap 0.9991 which prevented packets from being captured until a BPF filter had been set. Fixes #168 (migrated from nmap/nmap#2037).

  • Allow capture statistics and captured packets remaining in the buffer to be retrieved when an adapter is removed. Fixes nmap/nmap#2036.

  • Use WMI instead of the Windows 10-only Get-NetAdapter Powershell cmdlet in the DiagReport tool. Fixes nmap/nmap#611.

Npcap 0.9991 [2020-05-04]

  • Switched our code signing certificate back to DigiCert after some users found older Windows versions could not validate the signature on our driver for versions 0.9985 through 0.9990. The driver is again dual-signed with SHA-1 and SHA-2 certificates. See #2012.

  • Major changes to management of Npcap driver's circular packet buffer, switching from per-CPU unshared segments to a single worker thread managing a queue of work items. This improves buffer utilization, reduces the amount of time spent processing in the network stack, and should reduce packet loss. See #1967.

  • Several performance-related improvements to the NDIS filter driver: Switched from SpinLocks to ReadWriteLocks for several crucial shared data structures, which will improve performance by reducing resource contention on multiprocessor systems, and introduced an object-pool allocation pattern for several frequently-used short-lifetime objects, improving performance by reducing memory allocations.

  • Again restore "unused" NDIS filter callbacks which cause Windows 7 to lose connectivity when they are removed. See #1998.

  • Include debug symbols for wpcap.dll in our debug symbols zip file at . Fixes #1844.

  • Fixed #1996: heap corruption in NPFInstall.exe since Npcap 0.9989 leading to hung installs when the "raw 802.11 traffic" option was checked.

  • Fixed #2014: Npcap OEM silent install produced a dialog when installing over an existing installation of the same version.

  • Uninstaller improvements related to removing the installation directory, properly killing processes using Npcap DLLs, not leaving a partial installation if a step fails. Fixes #2013 and #2015.

Npcap 0.9990 [2020-04-04]

  • Improve compatibility with WinPcap's behavior regarding injected traffic. WinPcap uses inefficient loopback to capture all outbound traffic, but allows PacketSetLoopbackBehavior() to avoid this for injected traffic. Because of Npcap's more efficient design, injected traffic was never looped back up to protocol drivers, causing problems for some users who relied on this behavior. Now, injected traffic follows the same path as with WinPcap, though ordinary traffic is unaffected. For highest efficiency without loopback, use PacketSetLoopbackBehavior(NPF_DISABLE_LOOPBACK). Fixes #1343, #1929, and GNS3/gns3-gui#2936

  • No longer honor NDIS_PACKET_TYPE_ALL_LOCAL set via PacketSetHwFilter(). This packet filter causes all local traffic to be routed through an unoptimized loopback path within NDIS, which was necessary to capture outgoing traffic in WinPcap but is no longer needed in Npcap. Instead, this value will be treated as NDIS_PACKET_TYPE_DIRECTED | NDIS_PACKET_TYPE_MULTICAST | NDIS_PACKET_TYPE_BROADCAST.

  • Fix a bug that caused TIMESTAMPMODE_QUERYSYSTEMTIME_PRECISE to fall back to TIMESTAMPMODE_QUERYSYSTEMTIME even when KeQuerySystemTimePrecise() was available. Fix by Mauro Levra in PR#23.

  • Installer will now install an intermediate CA cert that was missing from some systems, which is needed to verify the driver's digital signature. Only affects Windows versions prior to Windows 10.

  • Backport a fix from libpcap needed to properly support NdisMediumWirelessWan. See #1573.

  • Include experimental support for AirPcap cards if airpcap.dll (not included) is installed.

Npcap 0.9989 [2020-03-19]

  • Fix a BSOD crash in NPF_OpenAdapter due to reading past the end of a string. Fixes #1924

  • Fix a BSOD crash (NULL pointer dereference) in NPF_Restart. Fixes #1964.

  • Fix a memory leak in the Loopback WFP filter. Additionally, WFP callbacks will be unregistered when all loopback captures are closed, reducing impact of related code when not in use. Fixes #1966.

  • New Packet.DLL function PacketSetTimestampMode() allows a user program to set the method used to timestamp packets as they arrive. See #1775. Supported modes are:

    • TIMESTAMPMODE_SINGLE_SYNCHRONIZATION - default monotonic timestamps based on KeQueryPerformanceCounter()
    • TIMESTAMPMODE_QUERYSYSTEMTIME - low-precision wall clock time based on KeQuerySystemTime()
    • TIMESTAMPMODE_QUERYSYSTEMTIME_PRECISE - high-precision wall clock time based on KeQuerySystemTimePrecise(), new in this release and only available on Windows 8 and newer. See #1407.
  • Remove some problematic timestamp modes: TIMESTAMPMODE_SYNCHRONIZATION_ON_CPU_WITH_FIXUP and TIMESTAMPMODE_SYNCHRONIZATION_ON_CPU_NO_FIXUP were undocumented; TIMESTAMPMODE_RDTSC was x86-only and not suitable for multi-processor systems. See #1829.

  • The Npcap SDK 1.05 will be released to include the new PacketSetTimestampMode() function.

Npcap 0.9988 [2020-03-05]

  • If a capture is in progress when the system is suspended, it will continue without interruption after the system is woken. This also prevents capture interruptions when the OS makes certain network stack changes. Fixes #1903.

  • If the npcap driver is stopped, Packet.dll will attempt to start it automatically. This feature requires Administrator privilege and had been removed in Npcap 0.9983. Fixes #1911.

  • Fix the check for fragmented packets in loopback capture. Closes PR #22.

  • Eliminate clone/block/inject pattern from loopback capture except for packets already injected by Npcap. Should fix #1529 and #1789.

  • Fix an issue in the Npcap OEM installer where silent mode would not detect a failure to install the npcap driver. Fixes #1910.

  • Improve the installer to avoid broken installations and allow the installer to continue if a broken installation is detected. Fixes #1935.

  • Formally removed support for Windows Vista and Server 2008 r1, which are no longer supported by Microsoft either. This allows us to support newer Windows WFP and NDIS features for better performance and compatibility. Folks who must still run these ancient Windows releases should use Npcap version 0.9984 from;O=D. That was the last Npcap release to support the old (and less secure) SHA-128 driver signatures required by these Windows Vista/2008. Please note that Windows Server 2008 r2 and Windows 7 are still supported in this release even though they have also passed their Microsoft end-of-life dates.

Npcap 0.9987 [2020-02-03]

  • Fix an issue where Npcap begins dropping large packets, then smaller ones until finally all packets are dropped. Our fix changes the way remaining free space in the kernel buffer is calculated, which ought to prevent the free space accounting from drifting from reality. Fixes #1891.

  • Fix a potential race condition when opening the loopback capture adapter. If two threads simultaneously determine that the WFP filters need to be registered, each may open a handle to the WFP engine using the same global pointer, leading to a double-free when the second one tries to close the handle.

  • Allow Packet.dll and the npcap driver to skip loopback-related operations, including WFP and WSK setup, if the LoopbackSupport Registry key is set to 0. This configuration will not be supported by the installer, but may serve as a workaround for problems that may be related to Npcap's loopback traffic capture and injection capability.

  • Ensure open handles to the Service Control Manager are closed on error in PacketGetFileVersion. Fixes #1882.

Npcap 0.9986 [2019-12-17]

  • Fix a driver signing issue that made Npcap 0.9985 uninstallable on default configurations of Windows 8.1 and older, as well as certain older Windows Server releases. Fixes #1856.

Npcap 0.9985 [2019-12-13]

  • The Nmap Project's (Insecure.Com LLC) code signing certificate has been renewed, and no longer exists as a SHA-1 certificate. Windows Vista and Server 2008 may therefore not recognize the digital signatures on the filter driver so a warning may be presented upon install. Please note that Microsoft is ending support for these operating systems in January 2020.

  • WinPcap API-compatible mode no longer installs a separate filter driver. Packet.DLL will translate NPF device names so that they are all serviced by the npcap.sys driver. The npf.sys driver has been removed. See #1812.

  • Improve the speed of pcap_findalldevs by reducing the number of calls to GetAdaptersAddresses, removing a redundant function call, and improving buffer reallocation. Patch by Tomasz Moń (#20).

  • Temporary DLLs unpacked during installation are now signed with our code signing certificate. Certain strict application whitelisting systems were complaining about unsigned DLL's loaded from a temporary directory.

  • Fixed a bug in the uninstaller preventing downgrades to prior versions of Npcap. On 64-bit Windows, the driver file npcap.sys was not properly removed, and Windows would not replace it with any older version. Fixes #1686.

Npcap 0.9984 [2019-10-30]

  • Update libpcap to 1.9.1. See the libpcap CHANGES file for this release. This update addresses several CVE-identified vulnerabilities.

  • Address several code quality issues identified by Charles E. Smith of Tangible Security using Coverity source code analysis.

  • Fixed processing of the "enforced" value for several command-line installer options. Fixes #1719.

  • The DisplayName value in the Uninstall registry key for Npcap no longer includes the version number, which has always been available in the DisplayVersion value. Instead, it will include the product name and edition, e.g. "Npcap" or "Npcap OEM". This value will also be recorded in the Edition value under the npcap service's Parameters registry key.

  • Fixed a couple of issues with the DiagReport tool used for bug report diagnostics: remove extraneous partial output lines (#1760), and avoid relying on the Server service to determine privilege level (#1757).

Npcap 0.9983 [2019-08-30]

  • Npcap can now detect newly-added network adapters without restarting the driver. Fixes #664.

  • Loopback capture and injection no longer requires the Npcap Loopback Adapter to be installed. This is a minor API change, so Nmap 7.80 and earlier will still require the adapter to do localhost scans, but Wireshark and most other software will not require changes. Loopback capture uses the device name NPF_Loopback instead of NPF_{GUID}, where GUID has to be looked up in the Registry. The Npcap Loopback Adapter can still be installed by selecting "Legacy loopback support" in the installer or using the /loopback_support=yes command-line option. TheLoopbackSupport Registry value will always be 0x00000001.

  • The DltNull Registry setting and the /dlt_null installer option are no longer supported. Loopback capture will use the DLT_NULL link type as described in the tcpdump documentation. Loopback packet injection will also use this link type instead of requiring a dummy Ethernet header to be constructed. The DltNull Registry value will still be present and set to 1 for software that consults this value.

  • Some operations like pcap_stats() can now be completed even after the adapter that was in use is removed. See #1650.

  • Fixed a crash that could happen when stopping the driver during a loopback traffic capture. Fixes #1678.

Npcap 0.9982 [2019-07-30]

  • Fix the packet statistics functionality used by pcap_stats(), which was broken in 0.9981. Fixes #1668.

  • Rework the flow of packets through the WFP callout driver that implements loopback traffic capture. This should prevent clobbering of redirect context data reported in #1529.

  • Restore the /dlt_null installer option to default to "yes" since it has been defaulting to "no" since Npcap 0.992. Using DLT_NULL for loopback capture is slightly more efficient than creating a dummy Ethernet header, which was the default before.

Npcap 0.9981 [2019-07-23]

  • When upgrading Npcap, do not uninstall the existing Npcap until the user clicks the Install button. Previously, the existing Npcap was uninstalled prior to the first options screen, so that canceling the upgrade left no working Npcap on the system.

  • Redefine the I/O control codes used by Npcap using the CTL_CODE macro to ensure proper access control and consistent parameter passing. This is not a published API, but the change will require that Packet.DLL and the npcap driver are the same version.

  • Fix a 1-byte overrun in NPFInstall.exe when killing processes with Npcap DLLs in use.

  • In cases where PacketOpenAdapter is given an adapter name in UTF-16LE, translate it to ASCII before doing string operations on it. See #1575.

  • Significant reorganization of internal data structures to reduce memory use and initialization overhead.

Npcap 0.997 [N/A]

  • Internal testing build, no public release.

Npcap 0.996 [2019-06-15]

  • Fix a crash when stopping the npcap driver service, such as when upgrading Npcap, DRIVER_IRQL_NOT_LESS_OR_EQUAL in NPF_DetachAdapter. Since Npcap 0.994 and 0.995 may crash when upgrading, the installer will offer to disable the npcap driver service if it is running, allowing the user to reboot and attempt the install again, avoiding a crash. Fixes #1626.

  • Ensure the uninstaller for the previous version of Nmap is called when upgrading. Npcap 0.95 through 0.995 erroneously skipped this step in simple non-silent upgrades, which could cause multiple Npcap Loopback Adapters to be installed.

Npcap 0.995 [2019-05-10]

  • Fix a crash reported via Microsoft crash telemetry, DRIVER_IRQL_NOT_LESS_OR_EQUAL in NPF_NetworkClassify introduced in Npcap 0.994. Fixes #1591.

Npcap 0.994 [2019-05-07]

  • Fix the installer options screen, which would immediately proceed to installation when you clicked on the "Support loopback traffic" option. Fixes #1577.

  • Use the /F option to SCHTASKS.EXE in the installer so that the npcapwatchdog task can be successfully overwritten if it is present, though newer uninstallers also remove the task. Fixes #1580.

  • Fix the CheckStatus.bat script run by the npcapwatchdog scheduled task to correctly match output of reg.exe on non-English systems. Fixes #1582.

  • Improve synchronization between WFP (Loopback) and NDIS (control) functions within the driver, which ought to improve stability during system sleep/suspend events, particularly an access violation in NPF_NetworkClassify observed via Microsoft crash telemetry.

Npcap 0.993 [2019-04-27]

  • Complete the fix for #1398 that was only partially applied in Npcap 0.992. Due to this partial fix, the user-provided buffer was double-freed, resulting in a BAD_POOL_CALLER BSoD. This issue was separately reported as #1568, and has been issued the identifier CVE-2019-11490.

  • Fix output of pcap_lib_version to again report "Npcap version 0.993, based on libpcap version 1.9.0" instead of "libpcap version 1.9.0 (packet.dll version 0.992)". Npcap 0.992 was the only version affected. Fixes #1566.

  • Fix a regression in loopback capture that was causing the loopback adapter to be missing from pcap_findalldevs until the driver was manually stopped and restarted. Fixes #1570.

  • Remove installer interface option "Automatically start the Npcap driver at boot time." Command-line and registry settings are still respected, but automatic start will be the default for all new installations, since manual start results in delays in network connectivity at boot. See #1502.

  • Avoid interpreting null or uninitialized memory as out-of-band media-specific information for purposes of constructing the Radiotap header when capturing in raw 802.11 monitor mode. Fixes #1528.

  • Ensure the uninstaller removes the npcapwatchdog scheduled task.

  • Avoid an uninstaller failure if DLLs and executables are in use during uninstall by causing them to be deleted at reboot. See #1555.

Npcap 0.992 [2019-03-24]

  • Update libpcap to 1.9.0. See the libpcap CHANGES file for this release and #1506.

  • Fix a bug in the fix for #1406 that caused capture filters to reject all packets when the packet header was offset from the start of the kernel data structure.

  • Fix a bug in the fix for #1398 that caused BSoD (BAD_POOL_CALLER) due to mismatch in functions used to allocate and free a data structure.

  • Remove installer interface option "Use DLT_NULL as the loopback interface' link layer protocol instead of DLT_EN10MB." Command-line and registry settings are still respected, but DLT_NULL will be the default for all new installations.

  • Remove installer interface option "Support 802.1Q VLAN tag when capturing and sending data," which was unsupported for three years. Support may be restored in future releases, but the option has not had any effect in earlier installers.

Npcap 0.991 [2019-03-14]

  • Fix a bug in the BPF packet filter engine that caused capture filters with byte offsets to reject packets due to fragmentation within NET_BUFFER structures. See #1406 and #1438.

  • Fix a bug that caused several network device drivers to crash when using the pcap_sendqueue_transmit function, due to queued network packets being allocated from paged memory that paged out before the drivers accessed it. See #1398.

  • Fix a crash (SYSTEM_EXCEPTION_NOT_HANDLED_M) in WSKCloseSocket due to double-free, reported via Microsoft crash telemetry.

  • Fix a BSOD inherited from WinPcap triggered when PacketGetStats is called with low system resources. See #1517.

  • Properly quote the path to the CheckStatus.bat script in the npcapwatchdog scheduled task. See #1513.

  • Fix errors when installing in WinPcap API-compatible mode over WinPcap when Npcap install directory does not already exist. See #1456.

Npcap 0.99-r9 [2019-01-22]

  • Install a scheduled task at startup to check whether the Npcap Loopback Adapter has been removed and restore it. Windows 10 feature updates remove the Adapter. See #1416.

  • Package the correct driver version. On some platforms, the Npcap 0.99-r8 installer would install the Npcap 0.99-r7 driver.

  • Fix a crash (REFERENCE_BY_POINTER) in NPF_ReleaseOpenInstanceResources reported via Microsoft crash telemetry. See #1419.

Npcap 0.99-r8 [2018-12-17]

  • Revert to using SERVICE_SYSTEM_START for the "Automatically start Npcap at boot" option. The previous value, SERVICE_AUTO_START had been introduced as a workaround for network interruption on Windows 7 that was finally solved in Npcap 0.99-r7. See #1208.

  • Removed extra Registry keywords from Npcap Loopback Adapter which were causing it to not appear properly in Windows API calls. Fixes #1368.

  • Detect in-use WinPcap installations before attempting to overwrite DLLs. Offer to terminate the processes just as we do for in-use Npcap.

  • Improved documentation based on WinPcap documentation including updates for Npcap changes. Example code builds on Visual Studio 2015 and works with Npcap. Npcap SDK 1.01 includes these changes.

  • Fix a crash in NPF_RegisterCallouts reported via Microsoft crash telemetry caused by a failure when opening the Npcap Loopback Adapter for packet capture.

  • On Windows 8 and Server 2012, Npcap will rebind to network adapters after installation to ensure a more complete fix to #1031.

Npcap 0.99-r7 [2018-07-05]

  • Fixed the installer so that Npcap in WinPcap API-compatible mode can do loopback capture. This capability is not guaranteed for future releases, but was only missing from 0.99-r3 to 0.99-r6. Native-mode Npcap was unaffected. Fixes #1213

  • Added a script, FixInstall.bat, to fix common problems with installations, such as those caused by Windows 10 feature upgrades. See #1216

  • Improved stability by restoring certain passthrough NDIS callbacks that are not used, but appear to cause connectivity problems if omitted. See #1208.

Npcap 0.99-r6 [2018-06-12]

  • Fixed installation on Windows 8 and Server 2012 so that Npcap is able to capture on adapters without requiring a reboot. Fixes #1031.

  • Fixed loss of networking on Windows 7 when Npcap was configured to start at boot. Using AUTO_START instead of SYSTEM_START for the Npcap driver service solves the problem. Fixes #1208.

  • Fixed a crash reported via Microsoft crash telemetry, DRIVER_IRQL_NOT_LESS_OR_EQUAL in NPF_IOControl when setting OID_GEN_CURRENT_LOOKAHEAD. Fixes #1194.

  • Fixed certain interactions between processes with open Npcap handles that could allow one process to stop other running captures from receiving packets. Fixes #1035.

Npcap 0.99-r5 [2018-05-01]

  • Restored installer code to silently uninstall WinPcap if silent installation in WinPcap API-compatible mode is needed (Npcap OEM only).

  • Removed several optional passthrough driver functions that can be handled more efficiently by NDIS, since Npcap was not using them.

  • Added validation of IRP parameters for additional security.

  • Fixed a crash reported via Microsoft crash telemetry, DRIVER_IRQL_NOT_LESS_OR_EQUAL in NPF_SendCompleteExForEachOpen when the system is suspended. Fixes #1193.

  • Bundle and install the correct public code signing certificate. The certificate used to sign Npcap was updated for Npcap 0.99-r4, but the public cert file included was not, leading to some unwanted publisher trust dialogs during installation.

Npcap 0.99-r4 [2018-04-19]

  • On Windows 7, if Npcap driver installation fails due to maximum NDIS filters installed, attempt to increase the limit. No such limit exists on other Windows versions. Fixes #1182.

  • Avoid some cmd.exe popup windows during installation. See #1188.

  • Improve the license to allow unlimited copies of Npcap to be used (removes the 5 copy limitation) if the copies are solely used for Nmap and/or Wireshark.

Npcap 0.99-r3 [2018-04-06]

  • Fix recording of the Npcap Loopback Adapter's name in the service registry key. Loopback packet injection was broken in WinPcap API-compatible mode in Npcap 0.99-r1 and 0.99-r2. Fixes #1165.

  • Fix a double-close of a Registry key which could cause a crash in Packet.dll when debugging. Fixes #1163.

Npcap 0.99-r2 [2018-03-13]

  • Fix installer to work on 32-bit Windows.

Npcap 0.99-r1 [2018-03-05]

  • We now offer an Npcap OEM Edition internal-use license. This provides all the advantages of Npcap OEM (such as the silent installer) and removes the 5-copy limitation of the free Npcap, while also providing for commercial support and updates. It is for companies who only want to use Nmap internally. We also still offer the Npcap OEM redistribution license for companies wanting to redistribute Npcap with their software. See

  • Improved installation of the Npcap Loopback Adapter, ensuring it can be correctly removed and reinstalled.

  • Packet.DLL now only looks in the driver service's Parameters Registry key for installation options; in future releases, Npcap may stop writing these options to the HKLM:\Software\Npcap registry key.

  • When NpcapHelper.exe is used for UAC elevation, the pipe it uses to communicate with the calling process is now restricted to the user SID of the calling process. Previously, any user could cause NpcapHelper to obtain handles to other devices, though the handles were only valid for the calling process.

  • Performed Visual Studio Code Analysis on Packet.DLL and cleaned up several code health issues.

  • Improved debug logging, error checking, and diagnostics throughout.

Npcap 0.98 [2018-01-10]

  • Fix digital signatures for some files: OEM drivers were missing the Microsoft Attestation signature required for Windows 10 1703, and the installer was missing the SHA-1 signature required for Windows Vista.

Npcap 0.97 [2017-11-27]

  • Only include data rate and channel fields in the RadioTap header if they are reported by the underlying WiFi card driver. See #1036.

  • When the Npcap installer detects that WinPcap is present, it will default to installing in WinPcap API-compatible mode, replacing WinPcap. This can be changed by the user in the interactive installer, or by setting the /winpcap_mode=no command-line option.

  • The Silent installation feature of the Npcap installer is now limited to the Npcap OEM edition.

Npcap 0.96 [2017-10-31]

  • Set the *IfType, *MediaType, and *PhysicalMediaType registry values for the Npcap Loopback Adapter. The values set should reduce the amount of configuration that Windows attempts to do on the adapter, preventing it from being labeled "Unknown Network."

  • Record the ID of the Npcap Loopback Adapter in the registry when creating it, instead of only in the installer. This allows users to remove and create the adapter with NPFInstall directly, without requiring a reinstallation of Npcap.

  • Expand the Npcap public license to allow 5 installations rather than only 1.

  • Fix memory layout and accounting when writing Radiotap headers in raw 802.11 monitor mode. Fixes #1001, #1028, and #1036.

Npcap 0.95 [2017-10-19]

  • When upgrading, existing installation options will be retrieved from the Registry. Command-line installer options will still override these.

  • The installer detects Win10pcap as distinct from WinPcap; since the installer cannot uninstall Win10pcap, WinPcap API-compatible mode will be disabled in the installer when it is present. Fixes #999.

  • The file is no longer dual-signed; since it was not a PE executable, only one signature is supported. The invalid signature was causing some installation failures. Fixes #994.

  • Silent installs will not downgrade the Npcap version unless the new /downgrade=yes option is given. Any version of Npcap OEM will be considered a "newer version" than any non-OEM version.

Npcap 0.94 [2017-08-29]

  • Npcap no longer prevents checksum offloading and Large Send Offloading on adapters that support them. This may cause problems with sniffing outgoing packets on those interfaces when those features are enabled, but users can disable them through standard Windows configuration means. Fixes #989

Npcap 0.93 [2017-07-27]

  • Move the driver's Service Registry values from the HKLM:\SYSTEM\CurrentControlSet\Services\npcap key to the Parameters subkey. Applying Windows upgrades such as Windows 10 Creators Update deletes nonstandard values from the service key; the Parameters subkey is where these should be stored instead.

  • Prevent the installer/uninstaller from crashing when faced with an incomplete Npcap installation, such as that created by applying a Windows version upgrade. Safely distinguish between old WinPcap installations and broken Npcap-in-WinPcap-API-mode installations. Fixes #906

Npcap 0.92 [2017-06-12]

  • Force overwrite of files in installer, since uninstallers from versions 0.78r5 through 0.81 do not remove npcap.sys, leading to mismatched driver vs DLL versions.

  • New installer commandline option to skip setting a restore point: /disable_restore_point=yes

Npcap 0.91 [2017-06-06]

  • Fix WiFi interruption with certain hardware. This is a regression introduced in Npcap 0.90, which had optimistically removed the fix from 0.10-r15.

Npcap 0.90 [2017-05-26]

  • Fix BSOD introduced in 0.85; Locking while being cleaned up is bad.

  • Fix WiFi interruption on Windows 7 in some circumstances, as demonstrated by inability to connect when Kaspersky Internet Security is installed.

Npcap 0.86 [2017-04-12]

  • Fix BSOD introduced in 0.85; wrong driver build had been packaged. Fixes #840

Npcap 0.85 [2017-04-10]

  • Fix BSOD by reverting to simpler pre-0.82 data structures but retaining the spinlock improvement that was the core of that fix.

Npcap 0.84 [2017-03-28]

  • Fix a failure of 64-bit Npcap when installed in Admin-Only mode. #814

Npcap 0.83 [2017-03-04]

  • Fix a crash caused by recieving loopback traffic after Windows starts to sleep. #721

  • Don't override CLI installer options like /wpcap_mode when WinPcap is found. #717

  • Restore the uninstaller instruction that deletes the npcap driver files.

Npcap 0.82 [2017-02-23]

  • Fix a crash that happened when many concurrent processes were using Npcap. If several of these quit during processing of a packet, the linked list of processes could become corrupted. Solved this by using a fixed array with copy-and-swap instead.

Npcap 0.81 [2017-02-16]

  • Moved distribution of executable installer to from Github.

  • Write log files in UTF-8 encoding to preserve localized error messages.

  • Report human-readable error when LWF filter fails to be installed.

  • Add *NdisDeviceType=1 key to registry for Loopback adapter. Fixes #653

Npcap 0.80 [2017-01-09]

  • Signed the uninstaller executable.

  • Removed the legacy code supporting Windows XP and earlier.

  • Added this CHANGELOG

  • Fixed a few null pointer dereferences that may have led to Blue Screens under some scenarios.

  • Restored changes from 0.78 r2 through 0.78 r4 that were accidentally omitted from 0.78 r5.

Npcap 0.78 r5 [2016-12-15]

  • Microsoft Attestation-signed drivers for Windows 10, required in Win10 1607. See #492

  • Removed Windows XP support from the executable installer. XP users can use WinPcap instead, as that is all that we were installing on that platform.

Npcap 0.78 r4 [2016-12-10]

  • Fixed the bug that "Npcap Loopback Adapter" can't be uninstalled.

Npcap 0.78 r3 [2016-12-10]

  • The uninstaller allows users to terminate processes that are using Npcap.

Npcap 0.78 r2 [2016-12-03]

  • The uninstaller lists the processes that are currently using Npcap, preventing a clean uninstall.

Npcap 0.78 [2016-11-23]

  • The uninstaller warns when it is unable to delete DLLs that are in use by applications.

Npcap 0.11 [2016-11-21]

  • Updated the WDK from 10.0.10586 to 10.0.14393.

Npcap 0.10 r18 [2016-11-08]

  • Improved the error message of invalid adapter name in WlanHelper.

Npcap 0.10 r17 [2016-11-07]

  • Built WlanHelper.exe in Unicode instead of Multi-Byte. This will fix the wrong display of non-English characters.

Npcap 0.10 r16 [2016-11-07]

  • Fixed the bug that some functions of WlanHelper.exe doesn't work.

Npcap 0.10 r15 [2016-11-05]

  • Fixed the bug that using Npcap to capture at the first time causes limited connectivity on Wi-Fi adapters.

Npcap 0.10 r14 [2016-11-03]

  • Fixed the bug that Npcap mode and WinPcap compatible mode can't use the loopback interface at the same time.

Npcap 0.10 r13 [2016-11-01]

  • Added the /sign_mode option for installer to choose to install SHA1-signed or SHA2-signed drivers.

Npcap 0.10 r12 [2016-10-25]

  • Fixed the issue that Nping shows both protocol unreachable and successful replies for "nping ".

Npcap 0.10 r11 [2016-10-24]

  • Fixed the issue that Nping shows both protocol unreachable and successful replies for "nping".

Npcap 0.10 r10 [2016-10-23]

  • The uninstaller will not show the finish page if run with "/Q".

Npcap 0.10 r9 [2016-10-17]

  • Fixed the BSoD that happens when the OS sleeps after using Npcap Loopback Adapter.

Npcap 0.10 r8 [2016-10-16]

  • Improved the error messages of WlanHelper.exe.

Npcap 0.10 r7 [2016-10-08]

  • Raw 802.11 capture is provided without re-installing the driver!

Npcap 0.10 r6 [2016-10-04]

  • Fixed the BSoD that NPF_RemoveFromGroupOpenArray() referenced the freed group head.

Npcap 0.10 r5 [2016-10-03]

  • Fixed the "PAGE FAULT IN NONPAGED AREA" BSoD about the group adapter removal reported by Pavel.

Npcap 0.10 r4 [2016-10-02]

  • Fixed some BSoDs that causes the system to halt.

Npcap 0.10 r3 [2016-10-02]

  • Now NPFInstall debug traces will be logged into C:\Program Files\Npcap\NPFInstall.log

Npcap 0.10 r2 [2016-09-21]

  • Fixed the BSoD that NPF_TapEx() accessed the CPU buffer of the OPEN_INSTANCE that was released.

Npcap 0.10 [2016-09-20]

  • Fixed the bug that PacketGetNetType() doesn't return the correct DLT_NULL value on Nmap.

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Npcap 0.06-r4 [2016-03-04]

  • The uninstallation window won't close itself now.

  • Fixed the problem that the uninstallation process won't end in the Task Manager.

  • System restore point will not be created in the uninstallation phase.

  • Improved the text display of the installer.

Npcap 0.06-r3 [2016-03-03]

  • Improved the creating system restore point support. Now Npcap installer will create a Windows system restore point named Before Npcap %VERSION% installs before actual installation process and create a point named Before Npcap %VERSION% uninstalls before uninstallation.

Npcap 0.06-r2 [2016-03-01]

  • Made the loopback feature optional in the installer. This option is checked by default.

  • Improved the creating system restore point logic by removing nested creation. A modified SysRestore plug-in is used:

Npcap 0.06 [2016-02-29]

  • Fixed the bug reported by yyjdelete that Npcap causes BSoD if the user tries to disable the adapter while sending packets.

Npcap 0.05-r16 [2016-02-29]

  • Added creating system restore point support. Now the installer has added an option called Create a system restore point before installing Npcap. It this option is checked, Npcap installer will create a Windows system restore point named Before installing Npcap before actual installation process. Returning back to this point will roll back all changes made by Npcap. Note: this option is NOT checked by default.

Npcap 0.05-r15 [2016-02-28]

Npcap 0.05-r14 [2016-02-25]

  • Fixed the driver signing error in Win7. We used the legacy SHA1 code signing cert to sign the Npcap driver in Win7, so no need for Win7 users to install KB3033929 patch any more.

  • This version Npcap is supposed to have fixed all signing errors, so it will successfully install on all the platforms: Vista, Win7, Win8, Win8.1 and Win10 without any prerequisites.

Npcap 0.05-r13 [2016-02-20]

Npcap 0.05-r12 [2016-02-16]

  • Signed the installer with better signing method

Npcap 0.05-r11 [2016-02-16]

Npcap 0.05-r10 [2016-02-04]

Npcap 0.05-r9 [2016-02-04]

  • Updated wpcap.dll from VS2005 to VS2013 and Packet.dll, NPFInstall.exe and NPcapHelper.exe from VS2010 to VS2013.

  • Additionally, I rolled back the driver signing improvement in 0.05 r8. Because it will show a Program Compatibility Assistant window said a well signed driver is needed. However, it's not true because npcap driver runs well by testing net start npf. To avoid this false message, I rolled back to the original signing commands.

Npcap 0.05-r8 [2016-02-01]

Npcap 0.05-r7 [2016-01-28]

  • Now send-to-Rx adapters can be multiple. The string specified in registry's SendToRx value should be semicolon-separated.

An example for one send-to-Rx adapter: '\Device{754FC84C-EFBC-4443-B479-2EFAE01DC7BF}

An example for two send-to-Rx adapters: '\Device{754FC84C-EFBC-4443-B479-2EFAE01DC7BF};\Device{F5A00000-E19A-4D17-B6D9-A23FE1852573}

Npcap 0.05-r6 [2016-01-27]

  • Now Npcap can have a send-to-Rx adapter. The send-to-Rx adapter will inject all its packets to "Receive Path" (Rx) instead of normal "Send Path" (Tx). So that instead of sending traffic to the network, the adapter will pretend to receive the injected traffic from the network in this way.

  • Currently only one send-to-Rx adapter is supported by specifying SendToRx value in Npcap driver service's registry key (need to restart the driver to take effect).

  • Npcap driver service's registry key is usually in: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\npf. In this key. You need to manually create a REG_SZ value named SendToRx, the value is the name of the adapter you want to be send-to-Rx adapter. The name is usually like format of \Device{F5A00000-E19A-4D17-B6D9-A23FE1852573}. You can query this value using Nmap's nmap --iflist command, you will get a similar value like \Device\NPF_{F5A00000-E19A-4D17-B6D9-A23FE1852573}, but they are NOT THE SAME. You need to remove the NPF_ in this string and copy it to registry's SendToRx value. Then reboot the driver by net stop npf and net start npf.

Npcap 0.05-r5 [2016-01-11]

  • Fixed the bug reported by Nuno Antonio Dias Ferreira that Npcap fails to retrieve the adapter list using NPF registry way.

Npcap 0.05-r4 [2015-12-17]

  • Fixed the bug reported by Tenzin Rigden that Npcap installer fails to install correct files in /S silent mode.

Npcap 0.05-r3 [2015-11-25]

  • Added Npcap's support for Vista, Npcap now will prepare separate binaries for Vista.

Npcap 0.05-r2 [2015-11-05]

  • Fixed the bug reported by Amos Sheldon that Npcap causes BSoD: ATTEMPTED_EXECUTE_OF_NOEXECUTE_MEMORY when using Wireshark on Win8, 10 x86.

Npcap 0.05 [2015-09-11]

  • Added the "DON'T LOOPBACK" feature, if software set PacketSetLoopbackBehavior() by disable, self-sent packets will not be received again.

  • Built the installer using NSIS with strlen_8192, so system "PATH" will be updated normally in most cases (PATH is less than 8192).

  • Added 128 CPU core support for Npcap, or Npcap will cause BSoD when running on 128-core system.

  • Improved the appearance and text of the installer.

Npcap 0.04-r9 [2015-08-31]

  • Fixed the bug that Npcap can't capture real loopback traffic after system is resumed from standby.

Npcap 0.04-r8 [2015-08-25]

  • Now PCAP_IF_LOOPBACK flag in pcap_if_t struct will be set for "Npcap Loopback Adapter" both for DLT_NULL mode and Fake Ethernet mode.

Npcap 0.04-r7 [2015-08-24]

  • PCAP_IF_LOOPBACK flag in pcap_if_t struct will be set for "Npcap Loopback Adapter" now, only for DLT_NULL mode

  • Fixed the bug that DLT_NULL mode can't be disabled in the driver.

Npcap 0.04-r6 [2015-08-23]

  • Packet.dll will return NdisMediumNull for "Npcap Loopback Adapter" now.

Npcap 0.04-r5 [2015-08-21]

  • Finished the DLT_NULL protocol support. But there's a problem that Wireshark didn't parse the loopback packets right, need fix.

Npcap 0.04-r4 [2015-08-21]

  • Npcap driver will return 65550 as "Maximum Packet Size" instead of default 1514 for "Npcap Loopback Adapter", which refers to Linux implementation.

Npcap 0.04-r3 [2015-08-18]

  • Fixed the bug reported by Pascal Quantin that WSK code fails to init if it is run without Administrator right, the effect is Npcap loopback adapter can't be opened.

Npcap 0.04-r2 [2015-08-16]

  • Modified wpcap.dll version to 0.04, and improved the error trace message for Winsock Kernel socket operations.

Npcap 0.04 [2015-08-15]

  • Fixed the SYSTEM_SERVICE_EXCEPTION BSoD caused by NdisFOidRequest call, this may help to fix the BAD_POOL_CALLER BSoD (I said "may" because this BSoD can't be reproduced).

  • Modified Nmap and Nping to be able to send loopback packets on Windows OS, here's a bug, Nmap still can't see reply packets. But the request and reply packets can be seen in Wireshark.

Npcap 0.03-r6 [2015-08-06]

  • Changed to static linked.

Npcap 0.03-r5 [2015-08-06]

  • Npcap can send loopback packets now!

Npcap 0.03-r4 [2015-08-05]

  • WSKTest can send IPv4 and IPv6 loopback packets based on Ethernet header now.

  • Added IPv6 send support for WSKTest.

  • WSKTest can send a self-constructed ICMPv4 request packet now

  • Fixed the INF file lacking section issue in WSKTest.

  • Updated WSKTest from VS 2013 to VS 2015.

Npcap 0.03-r3 [2015-08-03]

Npcap 0.03-r2 [2015-07-30]

  • Improved WSK send code, update code format

Npcap 0.03 [2015-07-27]

Npcap 0.02-r4 [2015-07-26]

Npcap 0.02-r3 [2015-07-24]

Npcap 0.02-r2 [2015-07-22]

  • Fixed the bug that "Npcap Loopback Adaprer" renaming fails in Win10 non-English editions.

Npcap 0.02 [2015-07-22]

  • Solve the "system error 2" issue

Npcap 0.01-r2 [2015-07-19]

Npcap 0.01 [2015-06-23]

  • Add option to restrict Npcap usage to Windows users with admin rights rather than all users.

Npcap Birthday (First Public Code Checkin)! [2013-06-24]

  • Npcap's birthday! While Gordon "Fyodor" Lyon and Yang Luo had been working on the idea for a couple of months, June 24, 2013 was the date that Yang checked in the first actual code with the Npcap name!