StudyToCert

All certifications / Linux+ / Lessons

CompTIA Linux+ XK0-006 · Domain 5: Troubleshooting

Security issues: SELinux denials, file permissions, SSH key permissions, locked accounts

▶ Watch the overview video

Last reviewed September 30, 2026 · Leer en español

Many 'it just stopped working' tickets are really security controls doing their job: SELinux (Security-Enhanced Linux) blocking an unexpected access, permissions that are too tight or too loose, SSH refusing a key, or an account locked after failed logins. The skill is to identify which control is responsible and fix the configuration without weakening security. Exam answers that switch a control off are almost always wrong; answers that make the smallest correct change are right.

Free account

Keep reading for free

Create a free StudyToCert account to read the rest of this lesson: 7 more sections, 7 key terms, a real-world example, an exam tip and self-check questions. Every lesson, lab and practice test is free with an account.

Sign up free Log in

Study Linux+ for free
A week-by-week plan with every lesson, quizzes, checkpoint tests, a practice exam and hands-on labs.
Open the Linux+ study plan