RHEL 7, 8, 9, 10 – Security Issues

Security issues in Red Hat Enterprise Linux (RHEL) can surface as login failures, service denials, SELinux blocks, firewall problems, authentication errors, or compliance violations.

This guide provides a structured troubleshooting methodology applicable to RHEL 7 through RHEL 10.

1. Identify the Type of Security Issue
Before making changes, determine what is being blocked.
User cannot log in → PAM / SSH / SELinux
Service not accessible → Firewall / SELinux
Permission denied → SELinux / file context
SSH connection refused → sshd / firewall
Application fails after reboot → SELinux labeling
Compliance scan failures → OpenSCAP / crypto policy

2. Check System Logs First (Golden Rule)
Authentication and Security Logs
/var/log/secure
systemd Journal (All Versions)
# journalctl -xe
# journalctl -u sshd

3. SELinux Troubleshooting (Most Common Issue)
SELinux is enabled by default in all RHEL versions.
Check SELinux Status
# getenforce
# sestatus
Identify SELinux Denials
# ausearch -m avc -ts recent
Or:
# journalctl | grep AVC
Interpret SELinux Alerts
# sealert -a /var/log/audit/audit.log
Fix SELinux Issues (Recommended Approach)
Restore File Contexts
# restorecon -Rv /path
Enable Required Booleans
# getsebool -a | grep httpd
# setsebool -P httpd_can_network_connect on
Temporary Disable (For Testing Only)
# setenforce 0
Permanent disable (NOT recommended):
# vi /etc/selinux/config

4. Firewall Issues (firewalld)
Check Firewall Status
# systemctl status firewalld
firewall-cmd --state
List Active Rules
# firewall-cmd --list-all
Allow a Service or Port
# firewall-cmd --add-service=http --permanent
# firewall-cmd --add-port=8080/tcp --permanent
# firewall-cmd --reload
Verify Zones
# firewall-cmd --get-active-zones

5. SSH Security Issues
Check SSH Service
systemctl status sshd
Verify SSH Configuration
# sshd -t
# vi /etc/ssh/sshd_config
Common issues:

• PermitRootLogin no
• PasswordAuthentication no
• Wrong SSH port

Restart SSH Safely
# sshd -t && systemctl restart sshd

6. User Authentication & PAM Issues
Verify User Account
# id username
# passwd -S username
Check Account Lockout
# faillog -u username
# pam_tally2 --user username    # RHEL 7
# faillock --user username          # RHEL 8+
Reset Failed Login Count
# faillock --user username --reset

7. File and Directory Permission Issues
Check Ownership
# ls -ld /path
Fix Permissions
# chmod 755 /path
# chown user:group /path
Permissions alone may not fix SELinux issues.

8. sudo Issues
Check sudo Access
# sudo -l
Validate sudoers File
# visudo
Check:
username ALL=(ALL) ALL

9. Security Updates and Patch Issues
Check Installed Security Updates
# yum updateinfo list security # RHEL 7
# dnf updateinfo list security # RHEL 8+
Apply Security Updates
# yum update --security
# dnf update --security

10. OpenSCAP & Compliance Failures
Scan System
# oscap xccdf eval --profile standard --results scan.xml /usr/share/xml/scap/ssg/content/ssg-rhel*.xml
Common Compliance Failures

• Password complexity
• SSH hardening
• File permissions
• Crypto policies

11. Crypto Policy Issues (RHEL 8+)
Check Current Policy
# update-crypto-policies --show
Set Default Policy
# update-crypto-policies --set DEFAULT

12. Auditd Issues
Check Audit Service
# systemctl status auditd
Search Audit Logs
# ausearch -k ssh

13. Container Security Issues (RHEL 8+)
SELinux + Containers
# podman inspect container_name | grep SELinux
Fix volume labels:
:Z or :z

14. Kernel & Security Module Issues
Check Loaded Modules
# lsmod
Rebuild SELinux Labels
# touch /.autorelabel
# reboot

15. Best Practices to Prevent Security Issues

• Keep SELinux enabled
• Monitor /var/log/secure
• Apply security patches regularly
• Use firewalld zones properly
• Test changes in non-production
• Enable audit logging

Conclusion
Security troubleshooting in RHEL 7, 8, 9, and 10 follows a consistent methodology:

• Identify blocked access
• Review logs
• Check SELinux and firewall
• Validate authentication and permissions
• Apply fixes systematically

Following these steps ensures secure, compliant, and stable systems in enterprise environments.