Automate ppp0 Interface Monitoring and Restart

Are you facing issues with your ppp0 interface losing its IP address? This can disrupt your network connectivity and create unnecessary downtime. Automate ppp0 interface monitoring and restart using a bash script combined with systemd and udev rules. This approach ensures that your ppp0 interface stays active and automatically recovers from disconnections.

Why Automate ppp0 Interface Monitoring and Restart?

The ppp0 interface, commonly used for point-to-point protocol connections, is prone to losing its IP address due to network interruptions. Manually restarting the interface can be tedious and may lead to prolonged downtime. By automating ppp0 interface monitoring and restart, you can minimize downtime and maintain a stable network connection.

Prerequisites

Before you begin, ensure you have:

• A Linux system with the ppp0 interface configured.
• Root or sudo privileges.

Step 1: Create the Bash Script

Create a bash script to check if the ppp0 interface has an IP assigned. If not, it will restart the interface and keep checking every 2 minutes.

Script: /usr/local/bin/check_ppp0.sh

#!/bin/bash

# Function to check if ppp0 has an IP address
check_ip() {
    ip_address=$(ip -4 addr show ppp0 | grep -oP '(?<=inets)d+(.d+){3}')
    
    if [[ -z "$ip_address" ]]; then
        echo "$(date) - IP Detected: NONE" | tee -a /var/log/ppp0_check.log
        return 1  # No IP assigned
    else
        echo "$(date) - IP Detected: $ip_address" | tee -a /var/log/ppp0_check.log
        return 0  # IP is assigned
    fi
}

# Function to restart the ppp0 interface
restart_interface() {
    echo "$(date) - No IP on ppp0. Restarting interface..." | tee -a /var/log/ppp0_check.log
    ifdown ppp0
    sleep 5
    ifup ppp0
}

# Check if ppp0 has an IP assigned
if ! check_ip; then
    restart_interface
    
    # Wait for 2 minutes (120 seconds) and check if IP is assigned
    for ((i=1; i<=24; i++)); do  # 24 checks with a 5-second sleep between them
        sleep 5
        if check_ip; then
            echo "$(date) - IP assigned to ppp0 after restart." | tee -a /var/log/ppp0_check.log
            exit 0
        fi
    done
    
    # If no IP assigned after 2 minutes, continue checking indefinitely
    echo "$(date) - Still no IP on ppp0. Continuing to check every 2 minutes." | tee -a /var/log/ppp0_check.log
    while true; do
        sleep 120  # Wait for 2 minutes
        if ! check_ip; then
            echo "$(date) - No IP on ppp0 after 2 minutes. Restarting interface again..." | tee -a /var/log/ppp0_check.log
            restart_interface
        fi
    done
else
    echo "$(date) - IP is assigned to ppp0. No action needed." | tee -a /var/log/ppp0_check.log
fi

Make the script executable:

sudo chmod +x /usr/local/bin/check_ppp0.sh

Step 2: Create a systemd Service for ppp0 Monitoring

To automate ppp0 interface monitoring and restart, create a systemd service to run the script as a background process.

Service File: /etc/systemd/system/check_ppp0.service

[Unit]
Description=Check and Restart ppp0 Interface if no IP is Assigned
After=network-online.target
Wants=network-online.target

[Service]
ExecStart=/usr/local/bin/check_ppp0.sh
Restart=always
RestartSec=10

[Install]
WantedBy=multi-user.target

Reload systemd, enable and start the service:

sudo systemctl daemon-reload
sudo systemctl enable check_ppp0.service
sudo systemctl start check_ppp0.service

Step 3: Create a udev Rule for ppp0 Interface

To enhance automation, add a udev rule that restarts the service when the ppp0 interface is disconnected.

udev Rule: /etc/udev/rules.d/99-ppp0-monitor.rules

ACTION=="remove", SUBSYSTEM=="net", KERNEL=="ppp0", RUN+="/bin/systemctl restart check_ppp0.service"

Reload udev rules:

sudo udevadm control --reload

Step 4: Monitor Logs and Test the Setup

The script logs all activities to /var/log/ppp0_check.log. Monitor the logs with:

tail -f /var/log/ppp0_check.log

To test the setup, manually disconnect ppp0:

sudo ifdown ppp0

The script should automatically detect the disconnection and attempt to restart the interface.

Conclusion

By automating ppp0 interface monitoring and restart, you ensure continuous connectivity and minimize network downtime. This solution efficiently handles IP loss scenarios by repeatedly checking the ppp0 interface and restarting it as needed. Integrating the bash script with systemd and udev rules provides a robust and reliable network management solution.

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