{{DISPLAYTITLE:toor (Unix) Toor, the word "root" spelled backwards, is an alternative

superuser In computing, the superuser is a special user account used for system administration. Depending on the operating system (OS), the actual name of this account might be root, administrator, admin or supervisor. In some cases, the actual name of th ...

account in

Unix-like A Unix-like (sometimes referred to as UN*X or *nix) operating system is one that behaves in a manner similar to a Unix system, although not necessarily conforming to or being certified to any version of the Single UNIX Specification. A Unix-li ...

operating systems, particularly BSD and variants.

Purpose

In Unix, it is traditional to keep the root

filesystem In computing, file system or filesystem (often abbreviated to fs) is a method and data structure that the operating system uses to control how data is stored and retrieved. Without a file system, data placed in a storage medium would be one larg ...

as small as reasonably possible, moving larger programs and rapidly changing data to other, optional parts of the system. This increases the likelihood that the system can be brought to a semi-usable state in the case of a partial system failure. It also means that the

account, necessary for repairing a broken system, should not depend on any programs outside of this small core. To this end, the root account is often configured with a shell which is small, efficient, and dependable, but awkward for daily use. The toor account is intended as a solution to this problem. It is identical to root, but is configured to use a different, more featureful shell. Alternately, toor may be configured with the emergency shell, allowing root the freedom to use the featureful one.

Implementation

In a Unix-like system, each user has a

user ID Unix-like operating systems identify a user by a value called a user identifier, often abbreviated to user ID or UID. The UID, along with the group identifier (GID) and other access control criteria, is used to determine which system resources a us ...

number, which is what the

kernel Kernel may refer to: Computing * Kernel (operating system), the central component of most operating systems * Kernel (image processing), a matrix used for image convolution * Compute kernel, in GPGPU programming * Kernel method, in machine lea ...

uses to distinguish users and to manage user permissions. User ID #0 is reserved as the superuser account, and is given permission to do anything on the system. Users log in by username, not by ID number, and a user's choice of login shell is also managed by name. This separation between name and number allows a given user ID to be associated with more than one username, each having its own shell.

Security considerations

The presence of a 'toor' account (or the presence of more than one account with a user ID of 0) triggers a warning in many security auditing systems. This is valuable, since if the

system administrator A system administrator, or sysadmin, or admin is a person who is responsible for the upkeep, configuration, and reliable operation of computer systems, especially multi-user computers, such as servers. The system administrator seeks to en ...

did not intend for a second superuser account, then it may mean that the system has been compromised. It may be argued that even an intentional 'toor' account is a security risk, since it provides a second point of attack for someone trying to illicitly gain superuser privileges on the system. However, if passwords are chosen and guarded carefully, the risk increase is minimal. For example,

NetBSD NetBSD is a free and open-source Unix operating system based on the Berkeley Software Distribution (BSD). It was the first open-source BSD descendant officially released after 386BSD was forked. It continues to be actively developed and is a ...

ships with a disabled 'toor' account, meaning that there is no password with which one can log into the system as 'toor'. This is not a security risk in itself, though it may generate security warnings as previously described. However, if the system is compromised, an administrator may be less likely to notice the enabling of a disabled account than the creation of a new one, especially if they have become accustomed to ignoring warnings about 'toor' from their (arguably misconfigured) security program.

References

System administration Operating system security Unix