AIX Security Mechanisms

In essence, AIX security is provided by gates that users must pass through in order to enter the AIX environment, and permission matrixes that determine what they are able to do once inside. In some contexts, Secure RPC passwords have been referred to as network passwords.

The overall system is composed of four gates and two permission matrixes.

Dialup gate

To access a given AIX environment from the outside through a modem and phone line, you must provide a valid login ID and dialup password.

Login gate

To enter a given AIX environment you must provide a valid login ID and user password.

File and Directory Matrix

Once you have gained access to a AIX environment, your ability to read, execute, modify, create, and destroy files and directories is governed by the applicable permissions matrix.

Root gate

To gain access to root privileges, you must provide a valid super user (root) password.

Secure RPC gate

In an NIS+ environment running at security level 2 (the default), when you try to use NIS+ services and gain access to NIS+ objects (servers, directories, tables, table entries, and so forth) your identity is confirmed by NIS+ using the Secure RPC process.

To enter the Secure RPC gate requires presentation of a Secure RPC password. Your Secure RPC password and your login password normally are identical and when that is the case you are passed through the gate automatically without having to re-enter your password. (In some contexts, Secure RPC passwords have been referred to as network passwords. See Secure RPC Password versus Login Password Problem for information about handling two passwords that are not the same.)

A set of credentials are used to automatically pass your requests through the Secure RPC gate. The process of generating, presenting, and validating your credentials is called authentication because it confirms who you are and that you have a valid Secure RPC password. This authentication process is automatically performed every time you request a NIS+ service.

In an NIS+ environment running in NIS-compatibility mode (also known as YP-compatibility mode), the protection provided by the Secure RPC gate is significantly weakened because everyone has read rights for all NIS+ objects and modify rights for those entries that apply to them regardless of whether or not they have a valid credential (that is, regardless of whether or not the authentication process has confirmed their identity and validated their Secure RPC password). Since that allows anyone to have read rights for all NIS+ objects and modify rights for those entries that apply to them, an NIS+ network running in compatibility mode is less secure than one running in normal mode. (In Secure RPC terminology, any user without a valid creditial is considered a member of the nobody class. See Authorization Classes for a description of the four classes.)

For details on how to create and administer NIS+ authentication and credentials, see Administering NIS+ Credentials.

NIS+ objects matrix

Once you have been properly authenticated to NIS+ your ability to read, modify, create, and destroy NIS+ objects is governed by the applicable permissions matrix. This process is called NIS+ authorization.

For details NIS+ permissions and authorization, see Administering NIS+ Access Rights.