it-knowledge/src/solutions/service-management.md

# Service Management Solutions

This section documents my solutions to service management scenarios, including systemd services, process management, and service configuration.

## Scenario: Web Server Configuration

### Original Problem
[To be filled with actual scenario]

### Environment
- OS Version: RHEL/Rocky Linux
- Initial State: [Initial service state]
- Required Outcome: [Desired service configuration]

### Solution Steps
1. Install and Enable Service
   ```bash
   # Install service
   sudo dnf install httpd
   
   # Enable and start service
   sudo systemctl enable --now httpd
   ```
   [Explanation of installation]

2. Configure Service
   ```bash
   # Configuration commands
   sudo vi /etc/httpd/conf/httpd.conf
   ```
   [Explanation of configuration]

3. Manage Service State
   ```bash
   # Restart service
   sudo systemctl restart httpd
   
   # Check status
   sudo systemctl status httpd
   ```
   [Explanation of management]

### Verification
```bash
# Check service status
systemctl status httpd

# Check port listening
ss -tunlp | grep httpd

# Test service
curl localhost
```

### Key Learnings
- Understanding of systemd
- Service configuration best practices
- Troubleshooting methodology

## Skills Demonstrated
- Service Management
- Process Control
- Log Analysis
- Security Configuration

[Additional scenarios will be documented here as completed] 

---
---

## Scenario: Time Synchronization and Security Configuration

### Original Problem
- Configure chronyd to sync with time server 'time.example.com'
- Configure firewall to allow HTTP (port 80) and HTTPS (port 443)
- Create an SELinux policy to allow Apache to listen on port 8080
- Configure SSH to disable root login and only allow key-based authentication
- Set up a cron job to run system updates every Sunday at 2 AM

### Environment
- OS Version: RHEL/Rocky Linux
- Initial State:
- Required Outcome:

### Solution Steps
1. Configure chronyd to sync with time server 'time.example.com'
   ```bash
   # Install chrony
   sudo dnf install chrony

   # Configure chronyd to sync with time server 'time.example.com'
   sudo vi /etc/chrony.conf

   # Add the following line to the file
   server time.example.com iburst

   # Save and exit
   :wq
   
   The output should show the chrony service enabled and running
   
   # Enable and start service
   sudo systemctl enable chronyd
   sudo systemctl start chronyd
   sudo systemctl status chronyd
   ```
   The output should show the chrony service enabled and running

2. Configure firewall to allow HTTP (port 80) and HTTPS (port 443)
   ```bash
   # Install firewalld
   sudo dnf install firewalld

   # Enable and start firewalld
   sudo systemctl enable --now firewalld

   # Configure firewall to allow HTTP (port 80) and HTTPS (port 443)
   sudo firewall-cmd --add-service=http --permanent
   sudo firewall-cmd --add-service=https --permanent
   ```
   The output should show the firewall rules added

3. Create an SELinux policy to allow Apache to listen on port 8080
   ```bash
   # Install policycoreutils
   sudo dnf install policycoreutils

   # Create an SELinux policy to allow Apache to listen on port 8080
   sudo semanage port -a -t http_port_t -p tcp 8080
   ```
   The output should show the SELinux policy created

4. Configure SSH to disable root login and only allow key-based authentication
   ```bash
   # Configure SSH to disable root login and only allow key-based authentication
   sudo vi /etc/ssh/sshd_config

   # Disable root login
   PermitRootLogin no

   # Allow key-based authentication
   PubkeyAuthentication yes

   # Save and exit
   :wq

   # Restart SSH service
   sudo systemctl restart sshd
   ```
   The output should show the SSH configuration updated

5. Set up a cron job to run system updates every Sunday at 2 AM
   ```bash
   # Set up a cron job to run system updates every Sunday at 2 AM
   sudo crontab -e

   # Add the following line to the file
   0 2 * * 0 sudo dnf update

   # Save and exit
   :wq
   
   # Check status of cron service
   sudo systemctl status cron
   ```
   The output should show the cron job added

### Verification
```bash
# Check chrony status
sudo systemctl status chronyd

# Check firewall status
sudo firewall-cmd --list-all

# Check SELinux status
sudo getenforce

# Check SSH status
sudo systemctl status sshd

# Check cron status
sudo systemctl status cron
```

### Key Learnings
- Understanding of systemd
- Understanding of SELinux
- Understanding of SSH
- Understanding of cron
- Understanding of firewall
- Understanding of time synchronization

## Skills Demonstrated
- Service Management
- SELinux Management
- SSH Configuration
- Cron Job Management
- Firewall Configuration
- Time Synchronization