Nmap Public Source License Version 0.91 - Annotated HTML Description
THIS IS JUST A DRAFT OF THE NPSL WHICH MAY OR MAY NOT BE APPLIED TO NMAP SOMEDAY - CURRENT VERSIONS OF NMAP ARE ACTUALLY DISTRIBUTED UNDER THIS LICENSE INSTEAD.
The NPSL itself is rather terse, so we have created this Annotated
HTML Nmap Public Source License in a best-effort attempt to make it
easier to understand. This version includes further explanations and reasoning behind the license terms. These annotations are not part
of the license itself, a legal document, or legal advice. If you need
to know exactly what the license requires, you need to read and
understand the license itself; if you need legal advice, talk to a
The annotations (such as the one you are reading now) should be
rendered as gray boxes to distinguish them from actual license text.
This license is based on the GNU General Public
License, version 2 (Exhibit A). Certain terms and conditions in this license
come from the Apache License,
version 2.0, the RealNetworks Public Source License, and the Academic Free
License, version 3.0.
The intent of this license is to establish freedom to share and change
the software regulated by this license under the open source model.
It also includes a Contributor Agreement and disclaims any warranty
on Covered Software. Proprietary software companies wishing to use or
incorporate Covered Software within their programs must contact
Licensor to purchase a separate license. Open source developers who
wish to incorporate parts of Covered Software into free software with
conflicting licenses may write Licensor to request a waiver
Open source authors: If your license is not compatible with this
one, we are sometimes willing to grant permission to use portions of Nmap
under a different license than this one (such as plain GPL or BSD). Contact
Fyodor for permission.
Proprietary vendors: This license does not allow you to
redistribute Nmap source code or the executable for use with your software
(stand alone or on an appliance). We do sell licenses which permit
this, and also include support and updates. Dozens of software
vendors already license Nmap technology such as host discovery, port
scanning, OS detection, version detection, and the Nmap Scripting Engine. Contact firstname.lastname@example.org for a quote.
This License represents the complete agreement concerning subject
matter hereof. It contains the license terms themselves, but not the
reasoning behind them or detailed explanations. For further
information about this License, see http://nmap.org/npsl/ . That
page makes a good faith attempt to explain this License, but it does
not and can not modify its governing terms in any way.
- "Contribution" means any work of authorship, including the
original version of the Work and any modifications or additions to
that Work or Derivative Works thereof, that is intentionally submitted
to Licensor by the copyright owner or by an
individual or Legal Entity authorized to submit on behalf of the
copyright owner. For the purposes of this definition, "submitted"
means any form of electronic, verbal, or written communication sent to
the Licensor or its representatives, including but not limited to
communication on electronic mailing lists, source code control
systems, web sites, and issue tracking systems that are managed by, or
on behalf of, the Licensor for the purpose of discussing and improving
the Work, but excluding communication that is conspicuously marked or
otherwise designated in writing by the copyright owner as "Not a
- "Contributor" means Licensor and any individual or Legal Entity
on behalf of whom a Contribution has been received by Licensor and
subsequently incorporated within the Work.
- "Covered Software" means the work of authorship, whether in Source or
Object form, made available under the License, as indicated by a
copyright notice that is included in or attached to the work
- "Derivative Work" or "Collective Work" means any work, whether in
Source or Object form, that is based on (or derived from) the Work and
for which the editorial revisions, annotations, elaborations, or other
modifications represent, as a whole, an original work of authorship.
It includes software as described in Section 3 of this License.
- "Executable" means Covered Software in any form other than Source
- "Externally Deploy" means to Deploy the Covered Software in any way
that may be accessed or used by anyone other than You, used to provide
any services to anyone other than You, or used in any way to deliver
any content to anyone other than You, whether the Covered Software is
distributed to those parties, made available as an application
intended for use over a computer network, or used to provide services
or otherwise deliver content to anyone other than You.
- "GPL" means the GNU General Public License Version 2, as published by the Free Software Foundation and provided in Exhibit A.
- "Legal Entity" means the union of the acting entity and all other
entities that control, are controlled by, or are under common control
with that entity. For the purposes of this definition, "control" means
(i) the power, direct or indirect, to cause the direction or
management of such entity, whether by contract or otherwise, or (ii)
ownership of fifty percent (50%) or more of the outstanding shares, or
(iii) beneficial ownership of such entity.
- "License" means this document, including Exhibits.
- "Licensor" means Insecure.Com LLC and its successors and assigns.
- "Main License Body" means all of the terms of this document, excluding
- "You" (or "Your") means an individual or Legal Entity exercising
permissions granted by this License.
2. General Terms
Covered Software is licensed to you under the terms of the GPL
(Exhibit A), with all the exceptions and clarifications noted in this
Main License Body. Where the terms in this Main License Body conflict
in any way with the GPL, the Main License Body terms shall take
precedence. These exceptions mean that You may not distribute Covered
Software or Derivative Works under plain GPL terms without special
permission from Licensor.
You are not required to accept this License. However, nothing else
grants You permission to use, copy, modify or distribute the software
or its derivative works. These actions are prohibited by law if You do
not accept this License. Therefore, by modifying, copying or
distributing the software (or any work based on the software), You
indicate your acceptance of this License to do so, and all its terms
and conditions. In addition, you agree to the terms of this License by
clicking the Accept button or downloading the software.
3. Derivative Works
This License (including the GPL portion) places important
restrictions on derived works. Licensor interprets that term quite
broadly. To avoid any misunderstandings, we consider software
to constitute a "derivative work" of Covered Software for the purposes of this
license if it does any of the following:
- Integrates source code from Covered Software
- Reads or includes Covered Software data files, such as
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
- Executes a helper program, module, or script to do any of the above.
This list is not exclusive, but is meant to clarify Licensor's
intentions with some common examples. Distribution of any works which
meet these criteria must be under the terms of this license (including
this Main License Body and GPL), with no additional conditions or
restrictions. They must abide by all restrictions that the GPL places
on derivative or collective works, including the requirements for
distributing their source code and allowing royalty-free
The idea here is to prevent companies from using open source Nmap
in their proprietary software or appliances. Some have in the past
distributed Nmap executables as part of expensive proprietary products
and refused to make the source available, claiming a loophole
based on strange interpretations of the GPL definition of derivative
and collective works. If companies take value from Nmap, they need to
contribute back to the project and the open source community by either
making their product/project compatible open source or buying a commercial
Another goal of this section is to help prevent companies and individuals from making and distributing malware-laden copies of Nmap. While criminal malware gangs are unlikely to pay attention to copyright law, we have also caught more mainstream companies such as CNET's Download.com doing this.
4. Contributor Agreement (Grant of Copyright and Patent Licenses)
Each Contributor hereby grants to Licensor a perpetual, worldwide,
non-exclusive, no-charge, royalty-free, irrevocable copyright license
to reproduce, prepare Derivative Works of, publicly display, publicly
perform, sublicense, and distribute the Contribution and such
Derivative Works in Source or Object form.
Each Contributor hereby grants to You and Licensor a perpetual,
worldwide, non-exclusive, no-charge, royalty-free, irrevocable (except
as stated in this section) patent license to make, have made, use,
offer to sell, sell, import, and otherwise transfer the Work, where
such license applies only to those patent claims licensable by such
Contributor that are necessarily infringed by their Contribution(s)
alone or by combination of their Contribution(s) with the Work to
which such Contribution(s) was submitted. If You institute patent
litigation against any entity (including a cross-claim or counterclaim
in a lawsuit) alleging that the Work or a Contribution incorporated
within the Work constitutes direct or contributory patent
infringement, then any patent licenses granted to You under this
License for that Work shall terminate as of the date such litigation
Contributors may impose different terms on their Contributions by
stating those terms in writing at the time the Contribution is made.
Contributors may withhold all authority from Licensor to incorporate
submissions by conspicuously marking or otherwise designating them in
writing as "Not a Contribution" at the time they make the work available.
We absolutely encourage and appreciate code contributions! But we
generally can't accept them with strings attached. It isn't fair to
contribute code to Nmap, then sue the users because you claim that
code violates a patent you hold. Similarly, we can't have people
sending patches to the Nmap development list, then claiming copyright
violation when we incorporate and redistribute them in Nmap. It is
also important that we retain full rights to relicense new versions of
Nmap, including incorporated Contributions. The inability to
relicense code has caused devastating problems for other Free Software
projects (such as KDE and NASM). We also make changes to this license
from time to time. In addition, we sell commercial licenses under
different terms, and we sometimes grant special licenses to other open
source projects for license compatibility. Note that we cannot revoke
or change the license for previously distributed versions of Nmap, so
any changes we make would only apply to future versions.
In addition to granting rights to us and all Nmap users, you retain
the rights as copyright holder to use your changes as you desire. If
you don't want us to incorporate your changes into Nmap under these
terms, just say so when you submit them (or don't submit them at all).
5. Disclaimer of Warranty and Limitation of Liability
Unless required by applicable law or agreed to in writing, Licensor
provides the Covered Software (and each Contributor provides its Contributions) on
an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
express or implied, including, without limitation, any warranties or
conditions of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR
A PARTICULAR PURPOSE. You are solely responsible for determining the
appropriateness of using or redistributing the Covered Software and assume any
risks associated with Your exercise of permissions under this License.
In no event and under no legal theory, whether in tort (including
negligence), contract, or otherwise, unless required by applicable law
(such as deliberate and grossly negligent acts) or agreed to in
writing, shall any Contributor be liable to You for damages, including
any direct, indirect, special, incidental, or consequential damages of
any character arising as a result of this License or out of the use or
inability to use the Covered Software (including but not limited to damages for
loss of goodwill, work stoppage, computer failure or malfunction, or
any and all other commercial damages or losses), even if such
Contributor has been advised of the possibility of such damages.
6. External Deployment
Some open source licenses require that any hosted solutions using
the product must also be open source. We only ask that you give Nmap
credit if you externally deploy it.
If You Externally Deploy Covered Software, such as hosting a
website designed to execute Nmap scans for users, the system and its
documentation must, if technically feasible, prominently display a
notice stating that the system uses the Nmap Security Scanner to
perform its tasks. If technically feasible, the notice must contain a
hyperlink to http://nmap.org/ or provide that URL in the text.
This License does not grant permission to use the trade names,
trademarks, service marks, or product names of the Licensor, except as
required for reasonable and customary use in describing the origin of
the Covered Software.
The main goal here is to avoid confusion and ensure that users know what they are getting. If someone modifies and redistributes Nmap, they need to call it something else so that users know it isn't an “official” Nmap release. This clause also helps prevent folks from adding malware/spyware/adware and then redistributing it as Nmap. We have previously caught numerous organizations doing that, including CNET Download.com.
While we don't want derivative works to be misrepresented as official Nmap releases, properly crediting Nmap is allowed and expected.
While this license doesn't grant permission to use the Nmap trademark, feel free to contact Fyodor for special permission if needed.
8. Termination for Patent Action
This License shall terminate automatically and You may no longer
exercise any of the rights granted to You by this License as of the
date You commence an action, including a cross-claim or counterclaim,
against Licensor or any licensee alleging that the Covered Software
infringes a patent. This termination provision shall not apply for an
action alleging patent infringement by combinations of the Covered Software
with other software or hardware.
9. Jurisdiction, Venue and Governing Law
This License is governed by the laws of the State of California and
the intellectual property laws of the United States of America,
excluding the jurisdiction's conflict-of-law provisions. Any
litigation or other dispute resolution between You and Licensor
relating to this License shall take place in the Northern District of
California, and You and Licensor hereby consent to the personal
jurisdiction of, and venue in, the state and federal courts within
that District with respect to this License. The application of the
United Nations Convention on Contracts for the International Sale of
Goods is expressly excluded.
10. Permission to link with OpenSSL
Licensee grants permission to link Covered Software with any version of
the OpenSSL library from OpenSSL.Org, and distribute linked
combinations including the two. You must obey this License in all
respects for all code used other than OpenSSL.
11. Waiver; Construction
Failure by Licensor or any Contributor to
enforce any provision of this License will not be deemed a waiver of
future enforcement of that or any other provision. Any law or
regulation which provides that the language of a contract shall be
construed against the drafter will not apply to this License.
If any provision of this License is invalid or unenforceable under
applicable law, it shall not affect the validity or enforceability of
the remainder of the terms of this License, and without further action
by the parties hereto, such provision shall be reformed to the minimum
extent necessary to make such provision valid and enforceable.
Exhibit A. The GNU General Public License Version 2
Version 2, June 1991
Copyright (C) 1989, 1991 Free Software Foundation, Inc.
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
The licenses for most software are designed to take away your
freedom to share and change it. By contrast, the GNU General Public
License is intended to guarantee your freedom to share and change free
software--to make sure the software is free for all its users. This
General Public License applies to most of the Free Software
Foundation's software and to any other program whose authors commit to
using it. (Some other Free Software Foundation software is covered by
the GNU Lesser General Public License instead.) You can apply it to
your programs, too.
When we speak of free software, we are referring to freedom, not
price. Our General Public Licenses are designed to make sure that you
have the freedom to distribute copies of free software (and charge for
this service if you wish), that you receive source code or can get it
if you want it, that you can change the software or use pieces of it
in new free programs; and that you know you can do these things.
To protect your rights, we need to make restrictions that forbid
anyone to deny you these rights or to ask you to surrender the rights.
These restrictions translate to certain responsibilities for you if you
distribute copies of the software, or if you modify it.
For example, if you distribute copies of such a program, whether
gratis or for a fee, you must give the recipients all the rights that
you have. You must make sure that they, too, receive or can get the
source code. And you must show them these terms so they know their
We protect your rights with two steps: (1) copyright the software, and
(2) offer you this license which gives you legal permission to copy,
distribute and/or modify the software.
Also, for each author's protection and ours, we want to make certain
that everyone understands that there is no warranty for this free
software. If the software is modified by someone else and passed on, we
want its recipients to know that what they have is not the original, so
that any problems introduced by others will not reflect on the original
Finally, any free program is threatened constantly by software
patents. We wish to avoid the danger that redistributors of a free
program will individually obtain patent licenses, in effect making the
program proprietary. To prevent this, we have made it clear that any
patent must be licensed for everyone's free use or not licensed at all.
The precise terms and conditions for copying, distribution and
This License applies to any program or other work which contains
a notice placed by the copyright holder saying it may be distributed
under the terms of this General Public License. The "Program", below,
refers to any such program or work, and a "work based on the Program"
means either the Program or any derivative work under copyright law:
that is to say, a work containing the Program or a portion of it,
either verbatim or with modifications and/or translated into another
language. (Hereinafter, translation is included without limitation in
the term "modification".) Each licensee is addressed as "you".
Activities other than copying, distribution and modification are not
covered by this License; they are outside its scope. The act of
running the Program is not restricted, and the output from the Program
is covered only if its contents constitute a work based on the
Program (independent of having been made by running the Program).
Whether that is true depends on what the Program does.
You may copy and distribute verbatim copies of the Program's
source code as you receive it, in any medium, provided that you
conspicuously and appropriately publish on each copy an appropriate
copyright notice and disclaimer of warranty; keep intact all the
notices that refer to this License and to the absence of any warranty;
and give any other recipients of the Program a copy of this License
along with the Program.
You may charge a fee for the physical act of transferring a copy, and
you may at your option offer warranty protection in exchange for a fee.
You may modify your copy or copies of the Program or any portion
of it, thus forming a work based on the Program, and copy and
distribute such modifications or work under the terms of Section 1
above, provided that you also meet all of these conditions:
You must cause the modified files to carry prominent notices
stating that you changed the files and the date of any change.
You must cause any work that you distribute or publish, that in
whole or in part contains or is derived from the Program or any
part thereof, to be licensed as a whole at no charge to all third
parties under the terms of this License.
If the modified program normally reads commands interactively
when run, you must cause it, when started running for such
interactive use in the most ordinary way, to print or display an
announcement including an appropriate copyright notice and a
notice that there is no warranty (or else, saying that you provide
a warranty) and that users may redistribute the program under
these conditions, and telling the user how to view a copy of this
License. (Exception: if the Program itself is interactive but
does not normally print such an announcement, your work based on
the Program is not required to print an announcement.)
These requirements apply to the modified work as a whole. If
identifiable sections of that work are not derived from the Program,
and can be reasonably considered independent and separate works in
themselves, then this License, and its terms, do not apply to those
sections when you distribute them as separate works. But when you
distribute the same sections as part of a whole which is a work based
on the Program, the distribution of the whole must be on the terms of
this License, whose permissions for other licensees extend to the
entire whole, and thus to each and every part regardless of who wrote it.
Thus, it is not the intent of this section to claim rights or contest
your rights to work written entirely by you; rather, the intent is to
exercise the right to control the distribution of derivative or
collective works based on the Program.
In addition, mere aggregation of another work not based on the Program
with the Program (or with a work based on the Program) on a volume of
a storage or distribution medium does not bring the other work under
the scope of this License.
You may copy and distribute the Program (or a work based on it,
under Section 2) in object code or executable form under the terms of
Sections 1 and 2 above provided that you also do one of the following:
Accompany it with the complete corresponding machine-readable
source code, which must be distributed under the terms of Sections
1 and 2 above on a medium customarily used for software interchange; or,
Accompany it with a written offer, valid for at least three
years, to give any third party, for a charge no more than your
cost of physically performing source distribution, a complete
machine-readable copy of the corresponding source code, to be
distributed under the terms of Sections 1 and 2 above on a medium
customarily used for software interchange; or,
Accompany it with the information you received as to the offer
to distribute corresponding source code. (This alternative is
allowed only for noncommercial distribution and only if you
received the program in object code or executable form with such
an offer, in accord with Subsection b above.)
The source code for a work means the preferred form of the work for
making modifications to it. For an executable work, complete source
code means all the source code for all modules it contains, plus any
associated interface definition files, plus the scripts used to
control compilation and installation of the executable. However, as a
special exception, the source code distributed need not include
anything that is normally distributed (in either source or binary
form) with the major components (compiler, kernel, and so on) of the
operating system on which the executable runs, unless that component
itself accompanies the executable.
If distribution of executable or object code is made by offering
access to copy from a designated place, then offering equivalent
access to copy the source code from the same place counts as
distribution of the source code, even though third parties are not
compelled to copy the source along with the object code.
You may not copy, modify, sublicense, or distribute the Program
except as expressly provided under this License. Any attempt
otherwise to copy, modify, sublicense or distribute the Program is
void, and will automatically terminate your rights under this License.
However, parties who have received copies, or rights, from you under
this License will not have their licenses terminated so long as such
parties remain in full compliance.
You are not required to accept this License, since you have not
signed it. However, nothing else grants you permission to modify or
distribute the Program or its derivative works. These actions are
prohibited by law if you do not accept this License. Therefore, by
modifying or distributing the Program (or any work based on the
Program), you indicate your acceptance of this License to do so, and
all its terms and conditions for copying, distributing or modifying
the Program or works based on it.
Each time you redistribute the Program (or any work based on the
Program), the recipient automatically receives a license from the
original licensor to copy, distribute or modify the Program subject to
these terms and conditions. You may not impose any further
restrictions on the recipients' exercise of the rights granted herein.
You are not responsible for enforcing compliance by third parties to
If, as a consequence of a court judgment or allegation of patent
infringement or for any other reason (not limited to patent issues),
conditions are imposed on you (whether by court order, agreement or
otherwise) that contradict the conditions of this License, they do not
excuse you from the conditions of this License. If you cannot
distribute so as to satisfy simultaneously your obligations under this
License and any other pertinent obligations, then as a consequence you
may not distribute the Program at all. For example, if a patent
license would not permit royalty-free redistribution of the Program by
all those who receive copies directly or indirectly through you, then
the only way you could satisfy both it and this License would be to
refrain entirely from distribution of the Program.
If any portion of this section is held invalid or unenforceable under
any particular circumstance, the balance of the section is intended to
apply and the section as a whole is intended to apply in other
It is not the purpose of this section to induce you to infringe any
patents or other property right claims or to contest validity of any
such claims; this section has the sole purpose of protecting the
integrity of the free software distribution system, which is
implemented by public license practices. Many people have made
generous contributions to the wide range of software distributed
through that system in reliance on consistent application of that
system; it is up to the author/donor to decide if he or she is willing
to distribute software through any other system and a licensee cannot
impose that choice.
This section is intended to make thoroughly clear what is believed to
be a consequence of the rest of this License.
If the distribution and/or use of the Program is restricted in
certain countries either by patents or by copyrighted interfaces, the
original copyright holder who places the Program under this License
may add an explicit geographical distribution limitation excluding
those countries, so that distribution is permitted only in or among
countries not thus excluded. In such case, this License incorporates
the limitation as if written in the body of this License.
The Free Software Foundation may publish revised and/or new versions
of the General Public License from time to time. Such new versions will
be similar in spirit to the present version, but may differ in detail to
address new problems or concerns.
Each version is given a distinguishing version number. If the Program
specifies a version number of this License which applies to it and "any
later version", you have the option of following the terms and conditions
either of that version or of any later version published by the Free
Software Foundation. If the Program does not specify a version number of
this License, you may choose any version ever published by the Free Software
If you wish to incorporate parts of the Program into other free
programs whose distribution conditions are different, write to the author
to ask for permission. For software which is copyrighted by the Free
Software Foundation, write to the Free Software Foundation; we sometimes
make exceptions for this. Our decision will be guided by the two goals
of preserving the free status of all derivatives of our free software and
of promoting the sharing and reuse of software generally.
BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN
OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED
OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS
TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE
PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,
REPAIR OR CORRECTION.
IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,
INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING
OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED
TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY
YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.
END OF TERMS AND CONDITIONS
For brevity, we've cut out the GPL's final section on “How to Apply These Terms to Your New Programs”, but you can find it here.