How do you create and manage User Profiles in AS400?

User profiles are fundamental to security on AS400 (now IBM i). They define who can access the system and what they can do. Here's a breakdown of how to create and manage them:

1. Creating User Profiles

CRTUSRPRF Command: The primary way to create a user profile is with the CRTUSRPRF command. You'll need security administrator (*SECADM) or security officer (*SECOFR) special authority to do this.
```
CRTUSRPRF USRPRF(username) PASSWORD(password) USRCLS(userclass) ... 
```
- USRPRF: The name of the user profile (e.g., SMITHJ).
- PASSWORD: The user's initial password.
- USRCLS: The user class (e.g., *USER, *PGMR, *SYSOPR, *SECADM, *SECOFR). This determines their base level of authority.
- There are many other parameters to customize the profile, such as initial program, menu, library list, and more.
WRKUSRPRF Command: You can also create a user profile using the WRKUSRPRF command. This provides a menu-driven interface to work with user profiles.

2. Managing User Profiles

CHGUSRPRF Command: Use the CHGUSRPRF command to modify existing user profiles. You can change passwords, user class, library lists, and other attributes.
```
CHGUSRPRF USRPRF(username) PASSWORD(newpassword) ...
```
DSPUSRPRF Command: The DSPUSRPRF command displays the details of a user profile.
```
DSPUSRPRF USRPRF(username)
```
DLTUSRPRF Command: Use the DLTUSRPRF command to delete a user profile.
```
DLTUSRPRF USRPRF(username)
```
WRKUSRPRF Command: As mentioned earlier, WRKUSRPRF provides a menu-driven interface to work with user profiles. You can use it to create, change, display, copy, or delete user profiles.

3. Key Concepts

User Classes: AS400 has predefined user classes that represent different levels of authority:
- *USER: Basic user with limited access.
- *PGMR: Programmer with authority to develop and test programs.
- *SYSOPR: System operator with authority to manage system operations.
- *SECADM: Security administrator with authority to manage system security.
- *SECOFR: Security officer with the highest level of authority.
Special Authorities: In addition to user class, you can grant specific special authorities to a user profile. These authorities allow users to perform specific tasks, such as managing objects, controlling jobs, or auditing security events.
Object Authority: User profiles are granted authority to access and manipulate objects (files, programs, etc.). You can grant different levels of authority, such as *READ, *UPDATE, *DELETE, *EXECUTE, and *ALL.
Group Profiles: You can create group profiles to group users together and grant them common authorities. This simplifies user management.

4. Security Best Practices

Strong Passwords: Enforce strong password policies, including minimum length, complexity requirements, and password expiration.
Principle of Least Privilege: Grant users only the authorities they need to perform their job duties.
Regular Audits: Regularly audit user profiles and their authorities to ensure they are appropriate.
Monitor User Activity: Monitor user activity for suspicious behavior.
Use Group Profiles: Use group profiles to simplify user management and ensure consistent authorities.