What license does Ubuntu fall into (GPL, MIT, a mix)? Would it be legal to modify it and redistribute my modified version?
Ubuntu is under a mix of licenses, each individual package has its copy right file under /usr/share/doc/PACKAGE/copyright, e.g. /usr/share/doc/gnome-panel/copyright All packages in main & universe are free software & can be modified & redistributed - restricted & multiverse packages fall under other licenses which may not allow this.
See http://www.ubuntu.com/project/about-ubuntu/licensing for more details
It is entirely legal.
Examples of custom Ubuntu's that are released:
Also, Ubuntu itself wouldn't be in existence if it wasn't for Debian.
There is a page on Ubuntu licensing, in particular:
Software installed by default
When you install Ubuntu, you will typically install a complete desktop environment. It is also possible to install a minimal set of software (just enough to boot your machine) and then manually select the precise software applications to install. Such a "custom" install is usually favoured by server administrators, who prefer to keep only the software they absolutely need on the server. All of the application software installed by default is free software. In addition, we install some hardware drivers that are available only in binary format, but such packages are clearly marked in the restricted component.
There is the problem of Ubuntu Branding.
The trademark policy explains this:
Permitted use Certain usages of the Trademarks are fine and no specific permission from us is needed.
Ubuntu is built by, and largely for, its community. We share access to the Trademarks with the entire community for the purposes of discussion, development and advocacy. We recognise that most of the open source discussion and development areas are for non-commercial purposes and will allow the use of the trademarks in this context, provided: the Trademark is used in a manner consistent with the Usage Guidelines below there is no commercial intent behind the use what you are referring to is in fact Ubuntu. If someone is confused into thinking that what isn't Ubuntu is in fact Ubuntu, you are probably doing something wrong there is no suggestion (through words or appearance) that your project is approved, sponsored, or affiliated with Ubuntu or its related projects unless it actually has been approved by and is accountable to the Ubuntu Community Council
So (in this non-lawyers opinion), as long as you make it clear that this is a
Ubuntu derivative (similar to how Ubuntu is based on Debian), you're fine.
However, I am NOT a lawyer, so this could be a flawed interpretation.
Ubuntu is a collection of thousands of computer programs and documents created by a range of individuals, teams and companies.
Each of these programs may come under a different licence. This licence policy describes the process that we follow in determining which software will be included by default in the Ubuntu operating system.
Copyright licensing and trademarks are two different areas of law, and we consider them separately in Ubuntu. The following policy applies only to copyright licences. We evaluate trademarks on a case-by-case basis.
Categories of software in Ubuntu
The thousands of software packages available for Ubuntu are organized into four key groups or components: main, restricted, universe and multiverse. Software is published in one of these components based on whether or not it meets our free software philosophy, and the level of support we can provide for it.
This policy only addresses the software that you will find in main and restricted, which contain software that is fully supported by the Ubuntu team and must comply with this policy.
Ubuntu 'main' component licence policy
All application software included in the Ubuntu main component:
Must include source code. The main component has a strict and non-negotiable requirement that application software included in it must come with full source code.
Must allow modification and distribution of modified copies under the same licence. Just having the source code does not convey the same freedom as having the right to change it. Without the ability to modify software, the Ubuntu community cannot support software, fix bugs, translate it, or improve it.
Ubuntu 'main' and 'restricted' component licence policy
All application software in both main and restricted must meet the following requirements: Must allow redistribution. Your right to sell or give away the software alone, or as part of an aggregate software distribution, is important because: You, the user, must be able to pass on any software you have received from Ubuntu in either source code or compiled form.
While Ubuntu will not charge licence fees for this distribution, you might want to charge to print Ubuntu CDs, or create your own customised versions of Ubuntu which you sell, and should have the freedom to do so.
Must not require royalty payments or any other fee for redistribution or modification.It's important that you can exercise your rights to this software without having to pay for the privilege, and that you can pass these rights on to other people on exactly the same basis.
Must allow these rights to be passed on along with the software. You should be able to have exactly the same rights to the software as we do.
Must not discriminate against persons, groups or against fields of endeavour. The licence of software included in Ubuntu can not discriminate against anyone or any group of users and cannot restrict users from using the software for a particular field of endeavour - a business for example. So we will not distribute software that is licensed "freely for non-commercial use".
Must not be distributed under a licence specific to Ubuntu. The rights attached to the software must not depend on the program being part of Ubuntu system. So we will not distribute software for which Ubuntu has a "special" exemption or right, and we will not put our own software into Ubuntu and then refuse you the right to pass it on.
Must not contaminate other software licences.The licence must not place restrictions on other software that is distributed along with it. For example, the licence must not insist that all other programmes distributed on the same medium be free software. May require source modifications to be distributed as patches. In some cases, software authors are happy for us to distribute their software and modifications to their software, as long as the two are distributed separately, so that people always have a copy of their pristine code. We are happy to respect this preference. However, the licence must explicitly permit distribution of software built from modified source code.
Documentation, firmware and drivers
Ubuntu contains licensed and copyrighted works that are not application software. For example, the default Ubuntu installation includes documentation, images, sounds, video clips and firmware. The Ubuntu community will make decisions on the inclusion of these works on a case-by-case basis, ensuring that these works do not restrict our ability to make Ubuntu available free of charge, and that you can continue to redistribute Ubuntu.
Software installed by default
When you install Ubuntu, you will typically install a complete desktop environment. It is also possible to install a minimal set of software (just enough to boot your machine) and then manually select the precise software applications to install. Such a "custom" install is usually favored by server administrators, who prefer to keep only the software they absolutely need on the server.
All of the application software installed by default is free software. In addition, we install some hardware drivers that are available only in binary format, but such packages are clearly marked in the restricted component.
It's a mix. Each package may be licensed under different terms.
It's generally legal to modify it and redistribute every package in main and universe, some packages may have restrictions on this, for example the firefox name and logo are trademarked so cannot be used without permission from Mozilla.
You can look at individual packages licences in /usr/share/doc/*/copyright
According to wikipedia, Ubuntu for the most part is GPL Licensed:
The only exceptions are some proprietary hardware drivers. The main license used is the GNU General Public License (GNU GPL) which, along with the GNU Lesser General Public License (GNU LGPL), explicitly declares that users are free to run, copy, distribute, study, change, develop and improve the software. On the other hand, there is also proprietary software available that can run on Ubuntu.
There are specific packages that aren't included (e.g. restricted drivers) that provide different licensing.
On the official ubuntu.org website, you can also find more on this topic.
It also explicitly indicates that there are 4 types of licenses offered in ubuntu packages:
The thousands of software packages available for Ubuntu are organised into four key groups or components: main, restricted, universe and multiverse. Software is published in one of these components based on whether or not it meets our free software philosophy, and the level of support we can provide for it.
As per this link, Ubuntu is a collection of a number of computer programs and each one of them may come under a different license.
As far as I know, the underlying Linux kernel is released under GNU GPL version 2:
And if you want to look up the license agreement for each one of the programs, then you can find it on a Ubuntu machine at this location: