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Root access

Revision as of 12:56, 19 February 2010

Warning: The steps described on this page could lead to severe damage to your system and/or device. Proceed at your own peril. It is likely that any breakage would be fixed by reflashing your device: however this will lose any settings not backed up.

Having root access is an important step for users interested in modifying things "under the covers" of their tablets; without it, you won't have the necessary permissions to make those modifications. Root access is disabled by default on new tablets. Thankfully, the steps to enable root access are simple.

Why do I want root?

Root access is not required to install additional applications through Application Manager, open X Terminal or use your tablet in day-to-day operation.

If you want to edit the underlying system configuration, install applications through the command line or other low-level tasks, you will require root access.

rootsh

Note: As rootsh is the simplest option, and does not require a desktop computer or running additional services, it is the recommended method for gaining root access.

rootsh is available in Extras, and can be installed from the Application manager if you have Extras enabled.

Then, from the shell, run sudo gainroot (or root for short). This will give you a root shell.

sudser

Note: Some scripts require rootsh to run properly, so it's recommended to have both suders and rootsh installed if you're using sudser.

sudser adds the user to sudoers so you can use the sudo command to run commands as root. It is available in Extras, and can be installed from the Application manager if you have Extras enabled.

It is not currently available for Fremantle (i.e. N900).

Then, from the shell, run sudo command. This will execute command with root privileges.

OpenSSH

1. Enable Extras (if you haven't already).
2. Install OpenSSH (client and server).
   • This will prompt you to change the root password from the default, rootme.
3. SSH into your tablet as root
   • For local access, run ssh root@localhost
   • For remote access, run ssh root@tablet's ip address
4. Use the root password entered at step (2) to log in.

To debug issues with SSH connections, use the SSH '-v' option.

(To get SSH X forwarding ('-X' option) to work, you need to install xauth (or xbase-clients) package and enable X forwarding in the SSH server configuration file on the machine where you're connecting to.)

Research & Development Mode (R&D or RD Mode)

Note: As R&D mode has other side effects beyond simply enabling root access (including several that may negatively impact battery life), it is not the recommended method for gaining root access. Use rootsh instead.

You can enable the R&D mode which enables you to execute sudo gainroot to get a root shell, simply follow the setup steps for flashing covered in updating the tablet firmware, then execute

sudo ./flasher-3.5 --enable-rd-mode -R

You are now in R&D mode, and the sudo gainroot script's check will be satisfied.

See also the R&D mode article.

A note on sudo

This information is aimed at people who come to maemo from other linux distributions (Debian for example) that may have used sudo in a different way.

In fremantle (Maemo 5) sudo is a key part of the system. It is used by system processes that are started as the user to provide access (as root) when needed.

Examples of this are: Media Tracker. The firmware version on the 'Settings' > 'About Product' page.

Both of these will malfunction if there are problems with sudo.

Sudo relies on '/etc/sudoers', a configuration file that details who can run what commands. '/etc/sudoers' is traditionally modified by using the 'visudo' command. DO NOT DO THIS ON MAEMO. In maemo sudoers is regenerated periodically from config snippets in '/etc/sudoers.d/', using 'visudo' can cause the slow death of your system as your edit gets pushed further down /etc/sudoers.

For those who don't know, '/etc/sudoers' works on a last match principle, so if your edit conflicts with entries above it, it will break those entries.

The 'correct' way to do this would be to put your entry in a file in '/etc/sudoers.s/'. I leave the detail of this up the experience of the end-user. Just be advised that using 'visudo' runs the risk of subtly breaking your system.