Overview

This solution provides an NTP time server that serves simulation time from the satellite emulator to Linux clients on the network. The system consists of:

1. Modified Scenario.py: Writes simulation time to simulation_time.txt
2. Standalone NTP Server: Reads the time file and serves it via NTP protocol
3. Linux Client Configuration: Configures clients to sync with the NTP server every 32 seconds

System Architecture

Satellite Emulator → Class/Scenario.py → simulation_time.txt
                                                    ↓
                                              ntpserver.py
                                                    ↓
                                            NTP Protocol (Port 123)
                                                    ↓
                                            Linux Clients (32s sync)

Step 1: Start the Satellite Emulator

1. Start your satellite emulator normally:

   python3 SatelliteEmulatorAPI.py
   

2. Load configuration and start simulation:
   • Upload your TOML configuration file
   • Initialize the scenario
   • Start the simulation

   The emulator will now write the current simulation time to simulation_time.txt in ISO 8601 format.

Step 2: Start the NTP Server

sudo python3 ntpserver.py

NTP Server Options

# Basic usage
python3 ntpserver.py

# Custom time file location
python3 ntpserver.py --file /path/to/simulation_time.txt

# Custom host and port
python3 ntpserver.py --host 192.168.1.100 --port 123

# Verbose logging
python3 ntpserver.py --verbose

# Help
python3 ntpserver.py --help

NTP Server Output

2024-01-15 10:30:45,123 - INFO - NTP Server started on 0.0.0.0:123
2024-01-15 10:30:45,123 - INFO - Reading simulation time from: simulation_time.txt
2024-01-15 10:30:45,123 - INFO - Waiting for NTP requests...
2024-01-15 10:30:47,456 - DEBUG - Received NTP request from 192.168.1.50:123
2024-01-15 10:30:47,456 - DEBUG - Sent NTP response to 192.168.1.50:123

Step 3: Configure Linux Clients

Method 1: Traditional NTP Daemon (Recommended)

1. Install NTP:

   # Ubuntu/Debian
   sudo apt update && sudo apt install ntp
      
   # RHEL/CentOS
   sudo yum install ntp
   

2. Configure NTP (/etc/ntp.conf):

   # Disable default NTP servers
   # server 0.pool.ntp.org iburst
   # server 1.pool.ntp.org iburst
   # server 2.pool.ntp.org iburst
   # server 3.pool.ntp.org iburst
   10.4.39.86
   # Add your NTP server
   server your-ntp-server-ip iburst
      
   # Set polling interval to 32 seconds (2^5)
   minpoll 5
   maxpoll 5
      
   # Other settings
   driftfile /var/lib/ntp/ntp.drift
   logfile /var/log/ntp.log
   

3. Restart NTP service:

   sudo systemctl restart ntp
   sudo systemctl enable ntp
   

4. Check sync status:

   ntpq -p
   

Method 2: Using Custom Port

If you used a custom port (e.g., 12345), modify /etc/ntp.conf:

server your-ntp-server-ip iburst port 12345
minpoll 5
maxpoll 5

Method 3: chrony (Alternative)

1. Install chrony:

   sudo apt install chrony
   

2. Configure (/etc/chrony.conf):

   server your-ntp-server-ip iburst
   minpoll 5
   maxpoll 5
   

3. Restart chrony:

   sudo systemctl restart chronyd
   sudo systemctl enable chronyd
   

Step 4: Verification

Check NTP Server Status

# Check if NTP server is running
sudo netstat -ulnp | grep :123

# Test NTP server manually
ntpdate -q your-ntp-server-ip

Check Client Synchronization

# Check NTP peers
ntpq -p

# Check system time sync
timedatectl status

# Force immediate sync
sudo ntpdate -u your-ntp-server-ip

Troubleshooting

Common Issues

1. Permission Denied (Port 123):

   # Solution: Run with sudo
   sudo python3 ntpserver.py
      
   # Or use custom port
   python3 ntpserver.py --port 12345
   

2. Time File Not Found:

   # Make sure satellite emulator is running
   # Check if simulation_time.txt exists
   ls -la simulation_time.txt
      
   # Verify file content
   cat simulation_time.txt
   

3. Clients Not Syncing:

   # Check firewall
   sudo ufw status
   sudo ufw allow 123/udp
      
   # Check NTP service status
   sudo systemctl status ntp
      
   # Check NTP logs
   tail -f /var/log/ntp.log
   

4. Time Drift Issues:

   # Check NTP statistics
   ntpdc -c monlist
      
   # Reset NTP
   sudo systemctl stop ntp
   sudo ntpdate -u your-ntp-server-ip
   sudo systemctl start ntp
   

Debug Mode

Enable verbose logging on NTP server:

python3 ntpserver.py --verbose

Network Testing

Test NTP connectivity:

# Test UDP connectivity
nc -u your-ntp-server-ip 123

# Test NTP protocol
ntpdate -d your-ntp-server-ip

File Locations

• Simulation Time File: simulation_time.txt (created by satellite emulator)
• NTP Server: ntpserver.py
• NTP Config: /etc/ntp.conf (Linux clients)
• NTP Logs: /var/log/ntp.log (Linux clients)

Security Considerations

1. Network Access: Restrict NTP server to trusted networks
2. Firewall: Only allow NTP traffic from authorized clients
3. File Permissions: Ensure simulation_time.txt has appropriate permissions
4. Root Access: NTP server on port 123 requires root privileges

Advanced Configuration

Custom Time File Format

The NTP server expects ISO 8601 format:

2024-01-15T10:30:45.123Z

Monitoring and Logging

Monitor NTP server activity:

# Enable verbose logging
python3 ntpserver.py --verbose

# Monitor log file
tail -f /var/log/ntp.log

# Monitor network traffic
sudo tcpdump -i any port 123

Summary

This solution provides a complete NTP time synchronization system for the satellite network emulator:

1. Satellite emulator writes simulation time to file
2. NTP server reads file and serves time via standard NTP protocol
3. Linux clients sync with simulation time every 32 seconds