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Nmap Network Scanning

Legal Notices

Nmap Copyright and Licensing

The Nmap Security Scanner is (C) 1996–2018 Insecure.Com LLC ("The Nmap Project"). Nmap is also a registered trademark of the Nmap Project. This program free software; you may redistribute and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; Version 2 (GPL), BUT ONLY WITH ALL OF THE CLARIFICATIONS AND EXCEPTIONS DESCRIBED HEREIN. This guarantees your right to use, modify, and redistribute this software under certain conditions. If you wish to embed Nmap technology into proprietary software, we sell alternative licenses (contact ). Dozens of software vendors already license Nmap technology such as host discovery, port scanning, OS detection, version detection, and the Nmap Scripting Engine.

Note that the GPL places important restrictions on derivative works, yet it does not provide a detailed definition of that term. To avoid misunderstandings, we interpret that term as broadly as copyright law allows. For example, we consider an application to constitute a derivative work for the purpose of this license if it does any of the following with any software or content covered by this license (Covered Software):

  • Integrates source code from Covered Software.

  • Reads or includes copyrighted data files, such as Nmap's nmap-os-db or nmap-service-probes.

  • Is designed specifically to execute Covered Software and parse the results (as opposed to typical shell or execution-menu apps, which will execute anything you tell them to).

  • Includes Covered Software in a proprietary executable installer. The installers produced by InstallShield are an example of this. Including Nmap with other software in compressed or archival form does not trigger this provision, provided appropriate open source decompression or de-archiving software is widely available for no charge. For the purposes of this license, an installer is considered to include Covered Software even if it actually retrieves a copy of Covered Software from another source during runtime (such as by downloading it from the Internet).

  • Links (statically or dynamically) to a library which does any of the above.

  • Executes a helper program, module, or script to do any of the above.

This list is not exclusive, but is meant to clarify our interpretation of derived works with some common examples. Other people may interpret the plain GPL differently, so we consider this a special exception to the GPL that we apply to Covered Software. Works which meet any of these conditions must conform to all of the terms of this license, particularly including the GPL Section 3 requirements of providing source code and allowing free redistribution of the work as a whole.

As another special exception to the GPL terms, the Nmap Project grants permission to link the code of this program with any version of the OpenSSL library which is distributed under a license identical to that listed in the included docs/licenses/OpenSSL.txt file, and distribute linked combinations including the two.

The Nmap Project has permission to redistribute Npcap, a packet capturing driver and library for the Microsoft Windows platform. Npcap is a separate work with it's own license rather than this Nmap license. Since the Npcap license does not permit redistribution without special permission, our Nmap Windows binary packages which contain Npcap may not be redistributed without special permission.

Any redistribution of Covered Software, including any derived works, must obey and carry forward all of the terms of this license, including obeying all GPL rules and restrictions. For example, source code of the whole work must be provided and free redistribution must be allowed. All GPL references to "this License", are to be treated as including the terms and conditions of this license text as well.

Because this license imposes special exceptions to the GPL, Covered Work may not be combined (even as part of a larger work) with plain GPL software. The terms, conditions, and exceptions of this license must be included as well. This license is incompatible with some other open source licenses as well. In some cases we can relicense portions of Nmap or grant special permissions to use it in other open source software. Please contact fyodor@nmap.org with any such requests. Similarly, we don't incorporate incompatible open source software into Covered Software without special permission from the copyright holders.

If you have any questions about the licensing restrictions on using Nmap in other works, we are happy to help. As mentioned above, we also offer an alternative license to integrate Nmap into proprietary applications and appliances. These contracts have been sold to dozens of software vendors, and generally include a perpetual license as well as providing support and updates. They also fund the continued development of Nmap. Please email for further information.

If you have received a written license agreement or contract for Covered Software stating terms other than these, you may choose to use and redistribute Covered Software under those terms instead of these.

Creative Commons License for this Nmap Guide

This Nmap Reference Guide is (C) 2005–2018 Insecure.Com LLC. It is hereby placed under version 3.0 of the Creative Commons Attribution License. This allows you redistribute and modify the work as you desire, as long as you credit the original source. Alternatively, you may choose to treat this document as falling under the same license as Nmap itself (discussed previously).

Source Code Availability and Community Contributions

Source is provided to this software because we believe users have a right to know exactly what a program is going to do before they run it. This also allows you to audit the software for security holes.

Source code also allows you to port Nmap to new platforms, fix bugs, and add new features. You are highly encouraged to send your changes to for possible incorporation into the main distribution. By sending these changes to Fyodor or one of the Insecure.Org development mailing lists, it is assumed that you are offering the Nmap Project the unlimited, non-exclusive right to reuse, modify, and relicense the code. Nmap will always be available open source, but this is important because the inability to relicense code has caused devastating problems for other Free Software projects (such as KDE and NASM). We also occasionally relicense the code to third parties as discussed above. If you wish to specify special license conditions of your contributions, just say so when you send them.

No Warranty

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License v2.0 for more details at http://www.gnu.org/licenses/gpl-2.0.html, or in the COPYING file included with Nmap.

It should also be noted that Nmap has occasionally been known to crash poorly written applications, TCP/IP stacks, and even operating systems. While this is extremely rare, it is important to keep in mind. Nmap should never be run against mission critical systems unless you are prepared to suffer downtime. We acknowledge here that Nmap may crash your systems or networks and we disclaim all liability for any damage or problems Nmap could cause.

Inappropriate Usage

Because of the slight risk of crashes and because a few black hats like to use Nmap for reconnaissance prior to attacking systems, there are administrators who become upset and may complain when their system is scanned. Thus, it is often advisable to request permission before doing even a light scan of a network.

Nmap should never be installed with special privileges (e.g. suid root). That would open up a major security vulnerability as other users on the system (or attackers) could use it for privilege escalation.

Third-Party Software and Funding Notices

This product includes software developed by the Apache Software Foundation. A modified version of the Libpcap portable packet capture library is distributed along with Nmap. The Windows version of Nmap utilizes the Libpcap-derived Ncap library instead. Regular expression support is provided by the PCRE library, which is open-source software, written by Philip Hazel. Certain raw networking functions use the Libdnet networking library, which was written by Dug Song. A modified version is distributed with Nmap. Nmap can optionally link with the OpenSSL cryptography toolkit for SSL version detection support. The Nmap Scripting Engine uses an embedded version of the Lua programming language. The Liblinear linear classification library is used for our IPv6 OS detection machine learning techniques (see the section called “IPv6 matching”). All of the third-party software described in this paragraph is freely redistributable under BSD-style software licenses.

Binary packages for Windows and Mac OS X include support libraries necessary to run Zenmap and Ndiff with Python and PyGTK. (Unix platforms commonly make these libraries easy to install, so they are not part of the packages.) A listing of these support libraries and their licenses is included in the LICENSES files.

This software was supported in part through the Google Summer of Code and the DARPA CINDER program (DARPA-BAA-10-84).

United States Export Control

Nmap only uses encryption when compiled with the optional OpenSSL support and linked with OpenSSL. When compiled without OpenSSL support, the Nmap Project believes that Nmap is not subject to U.S. Export Administration Regulations (EAR) export control. As such, there is no applicable ECCN (export control classification number) and exportation does not require any special license, permit, or other governmental authorization.

When compiled with OpenSSL support or distributed as source code, the Nmap Project believes that Nmap falls under U.S. ECCN 5D002 (Information Security Software). We distribute Nmap under the TSU exception for publicly available encryption software defined in EAR 740.13(e).

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