202-450 Exam Dumps : LPIC-2 - Exam 202 (part 2 of 2), version 4.5

To prevent anonymous FTP users from listing uploaded file names, the upload directory must not have the read or execute permission set for the anonymous user or group. The read permission allows the user to view the contents of a file or directory, while the execute permission allows the user to enter or search a directory. Therefore, removing both permissions will prevent the user from accessing or listing the files in the upload directory. However, the write permission can be left on, as it allows the user to create or modify files in the directory, which is the purpose of an upload directory. References:

• LPIC-2 Exam 202-450 Objectives, Topic 211: File Sharing, Objective 211.2: Manage FTP Service, Weight: 3
• LPIC-2 Linux Professional Institute Certification Study Guide: Exam 201 and Exam 202, Chapter 9: File Sharing, FTP, p. 353-354
• Linux File Permissions Explained, Read, Write, and Execute Permissions, p. 2-4

 The required control flag means that the PAM module is essential for the authentication process. If the module fails, the whole authentication fails. However, unlike the requisite control flag, the required control flag does not stop the execution of the remaining modules of the same type. This allows the user to receive feedback from all the modules, such as password expiration warnings or account lockout messages. References:

• Linux Professional Institute LPIC-2 Exam 202-450 Objectives, Topic 211: System Security, Objective 211.2: Configuring PAM, Weight: 5
• PAM Control Flags, System Administration Guide: Security Services, Oracle
• 10.2. About PAM Configuration Files, System-Level Authentication Guide, Red Hat Enterprise Linux 7, Red Hat Customer Portal
• 4. The Linux-PAM configuration file, SCO Group

The http_access directive for Squid allows or denies access to the web resources based on defined access control lists (ACLs). The syntax of the http_access directive is:

http_access allow|deny [!]aclname …

The directive takes one or more ACL names as arguments, separated by spaces. The first argument is either allow or deny, indicating the action to be taken if the ACLs match. The optional ! character before an ACL name negates the result of that ACL.

To allow users in the ACL named sales_net to only access the Internet at times specified in the time_acl named sales_time, the correct http_access directive is:

http_access allow sales_net sales_time

This directive means that if the client IP address matches the sales_net ACL and the request time matches the sales_time ACL, then the access is allowed. Otherwise, the access is denied or the next http_access directive is evaluated.