Under what license is Ubuntu? Can it be legally modified and distributed?

Solution 1:

It is entirely legal.

Examples of custom Ubuntu's that are released:

• Linux Mint

• Elementary OS

Also, Ubuntu itself wouldn't be in existence if it wasn't for Debian.

More on that relationship here

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.

(emphasis mine)

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.

Community advocacy.

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.

Solution 2:

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