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The Network Information Service, or NIS, is a client–server directory service protocol for distributing system configuration data such as user and host names between computers on a computer network. Sun Microsystems developed the NIS; the technology is licensed to virtually all other Unix vendors.
Unix security refers to the means of securing a Unix or Unix-like operating system. A secure environment is achieved not only by the design concepts of these operating systems, but also through vigilant user and administrative practices.
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 the account is not the determining factor; on Unix-like systems, for example, the user with a user identifier (UID) of zero is the superuser, regardless of the name of that account; and in systems which implement a role based security model, any user with the role of superuser can carry out all actions of the superuser account. The principle of least privilege recommends that most users and applications run under an ordinary account to perform their work, as a superuser account is capable of making unrestricted, potentially adverse, system-wide changes.
passwd is a command on Unix, Plan 9, Inferno, and most Unix-like operating systems used to change a user's password. The password entered by the user is run through a key derivation function to create a hashed version of the new password, which is saved. Only the hashed version is stored; the entered password is not saved for security reasons.
Capability-based security is a concept in the design of secure computing systems, one of the existing security models. A capability is a communicable, unforgeable token of authority. It refers to a value that references an object along with an associated set of access rights. A user program on a capability-based operating system must use a capability to access an object. Capability-based security refers to the principle of designing user programs such that they directly share capabilities with each other according to the principle of least privilege, and to the operating system infrastructure necessary to make such transactions efficient and secure. Capability-based security is to be contrasted with an approach that uses traditional UNIX permissions and Access Control Lists.
A flat-file database is a database stored in a file called a flat file. Records follow a uniform format, and there are no structures for indexing or recognizing relationships between records. The file is simple. A flat file can be a plain text file, or a binary file. Relationships can be inferred from the data in the database, but the database format itself does not make those relationships explicit.
In cryptography, a salt is random data fed as an additional input to a one-way function that hashes data, a password or passphrase. Salting helps defend against attacks that use precomputed tables, by vastly growing the size of table needed for a successful attack. It also helps protect passwords that occur multiple times in a database, as a new salt is used for each password instance. Additionally, salting does not place any burden on users.
The Linux and Unix access rights flags setuid and setgid allow users to run an executable with the file system permissions of the executable's owner or group respectively and to change behaviour in directories. They are often used to allow users on a computer system to run programs with temporarily elevated privileges to perform a specific task. While the assumed user id or group id privileges provided are not always elevated, at a minimum they are specific.
In Unix-like systems, multiple users can be put into groups. POSIX and conventional Unix file system permissions are organized into three classes, user, group, and others. The use of groups allows additional abilities to be delegated in an organized fashion, such as access to disks, printers, and other peripherals. This method, among others, also enables the superuser to delegate some administrative tasks to normal users, similar to the Administrators group on Microsoft Windows NT and its derivatives.
The Windows Registry is a hierarchical database that stores low-level settings for the Microsoft Windows operating system and for applications that opt to use the registry. The kernel, device drivers, services, Security Accounts Manager, and user interfaces can all use the registry. The registry also allows access to counters for profiling system performance.
The gecos field, or GECOS field is a field in each record in the /etc/passwd file on Unix and similar operating systems. On UNIX, it is the 5th of 7 fields in a record.
A directory traversal attack exploits insufficient security validation or sanitization of user-supplied file names, such that characters representing "traverse to parent directory" are passed through to the operating system's file system API. An affected application can be exploited to gain unauthorized access to the file system.
The Computer Oracle and Password System (COPS) was the first vulnerability scanner for Unix operating systems to achieve widespread use. It was created by Dan Farmer while he was a student at Purdue University. Gene Spafford helped Farmer start the project in 1989.
In computing, the Hesiod name service originated in Project Athena (1983–1991). It uses DNS functionality to provide access to databases of information that change infrequently. In Unix environments it often serves to distribute information kept in the /etc/passwd, /etc/group, and /etc/printcap files, among others. Frequently an LDAP server is used to distribute the same kind of information that Hesiod does. However, because Hesiod can leverage existing DNS servers, deploying it to a network is fairly easy.
In the X Window System, an X session manager is a session management program, a program that can save and restore the current state of a set of running applications, including window manager.
chsh is a command on Unix-like operating systems that is used to change a login shell. Users can either supply the pathname of the shell that they wish to change to on the command line, or supply no arguments, in which case chsh allows the user to change the shell interactively.
A number of computer operating systems employ security features to help prevent malicious software from gaining sufficient privileges to compromise the computer system. Operating systems lacking such features, such as DOS, Windows implementations prior to Windows NT, CP/M-80, and all Mac operating systems prior to Mac OS X, had only one category of user who was allowed to do anything. With separate execution contexts it is possible for multiple users to store private files, for multiple users to use a computer at the same time, to protect the system against malicious users, and to protect the system against malicious programs. The first multi-user secure system was Multics, which began development in the 1960s; it wasn't until UNIX, BSD, Linux, and NT in the late 80s and early 90s that multi-tasking security contexts were brought to x86 consumer machines.
In computer programming, a handle is an abstract reference to a resource that is used when application software references blocks of memory or objects that are managed by another system like a database or an operating system.
Secure coding is the practice of developing computer software in such a way that guards against the accidental introduction of security vulnerabilities. Defects, bugs and logic flaws are consistently the primary cause of commonly exploited software vulnerabilities. Through the analysis of thousands of reported vulnerabilities, security professionals have discovered that most vulnerabilities stem from a relatively small number of common software programming errors. By identifying the insecure coding practices that lead to these errors and educating developers on secure alternatives, organizations can take proactive steps to help significantly reduce or eliminate vulnerabilities in software before deployment.
A user is a person who utilizes a computer or network service.
References
- The vipw manpage, 26 September 1997, in the Debian passwd package version 1:4.0.13-6
