Troubleshooting

Troubleshooting Guide

🚨 Common Issues and Solutions

Application Won't Start

Permission Denied Errors

Problem: Application fails to start with permission errors

Error: Permission denied
Error: Access denied
Error: Administrator privileges required

Solutions:

Windows: Right-click executable → "Run as administrator"
Linux/macOS: Use sudo ./DHCPMonitor
Check UAC: Disable User Account Control temporarily
File Permissions: Verify executable has proper permissions

Missing Dependencies

Problem: Application crashes on startup with missing library errors

Error: Cannot find libpcap
Error: Missing wpcap.dll
Error: Npcap not found

Solutions:

Windows: Install Npcap from npcap.com
Linux: sudo apt install libpcap-dev (Ubuntu/Debian)
macOS: brew install libpcap
Reinstall: Uninstall and reinstall the application

Corrupted Installation

Problem: Application starts but behaves unexpectedly

Random crashes
Missing features
Incorrect behavior

Solutions:

Clean Uninstall: Remove all application files
Clear Cache: Delete temporary and cache files
Fresh Install: Download and install latest version
System Restore: Restore system to previous state

Network Interface Issues

No Interfaces Detected

Problem: Application shows "No network interfaces found"

Empty interface dropdown
Error message about no interfaces

Solutions:

Check Privileges: Ensure running as administrator/root
Verify Adapters: Check if network adapters are active
Driver Issues: Update network adapter drivers
Firewall: Check if firewall is blocking access
Antivirus: Temporarily disable antivirus software

Interface Not Working

Problem: Interface is detected but capture fails

Interface shows in list but won't capture
Error when starting capture

Solutions:

Interface Status: Verify interface is active and connected
Promiscuous Mode: Enable promiscuous mode if needed
Other Applications: Close other network monitoring tools
Interface Reset: Disable and re-enable network interface
System Restart: Restart computer to reset network stack

Wrong Interface Selected

Problem: Capturing from wrong network interface

Capturing from loopback instead of physical interface
Capturing from wrong network segment

Solutions:

Interface Selection: Manually select correct interface
Interface Priority: Set preferred interface order
Network Topology: Understand your network layout
Test Capture: Use small test to verify correct interface

Packet Capture Problems

No Packets Captured

Problem: Capture starts but no packets are displayed

Capture status shows "Running" but no data
Empty logs despite active network

Solutions:

Check Traffic: Verify there is DHCP traffic on network
Filter Issues: Check if filters are too restrictive
Buffer Size: Increase capture buffer size
Timeout Settings: Adjust capture timeout values
Network Activity: Generate DHCP traffic (connect new device)

Incomplete Packet Data

Problem: Packets captured but information is missing

Missing IP addresses
Incomplete DHCP options
Truncated packet data

Solutions:

Buffer Size: Increase capture buffer size
Packet Length: Check maximum packet length settings
Filter Issues: Verify filters aren't truncating packets
Network Issues: Check for network packet fragmentation
Application Settings: Verify packet parsing settings

High Packet Loss

Problem: Many packets are dropped or missed

High error count in statistics
Missing expected packets

Solutions:

Buffer Size: Increase capture buffer significantly
System Resources: Close other applications
Network Load: Reduce network traffic if possible
Hardware: Use dedicated network monitoring hardware
Capture Threads: Adjust number of capture threads

Performance Issues

High CPU Usage

Problem: Application uses excessive CPU resources

System becomes slow
High CPU percentage in task manager

Solutions:

Polling Interval: Increase UI update frequency
Buffer Management: Reduce log buffer size
Filter Optimization: Use more efficient filters
Background Tasks: Disable unnecessary background processing
System Resources: Close other resource-intensive applications

High Memory Usage

Problem: Application consumes too much memory

Memory usage grows over time
System becomes unresponsive

Solutions:

Log Retention: Reduce number of logs kept in memory
Cleanup Interval: Increase automatic cleanup frequency
Export Data: Regularly export and clear logs
Buffer Limits: Set lower buffer size limits
Restart Application: Restart to clear memory

Slow Interface Response

Problem: User interface is slow or unresponsive

Buttons take time to respond
Scrolling is choppy
Interface freezes temporarily

Solutions:

Reduce Log Display: Show fewer log entries at once
Update Frequency: Lower UI update frequency
Background Processing: Move heavy tasks to background
System Resources: Free up system resources
Application Restart: Restart to reset performance

Configuration Problems

Settings Not Saved

Problem: Configuration changes are not persistent

Settings revert after restart
Changes don't take effect

Solutions:

File Permissions: Check configuration file permissions
File Location: Verify configuration file location
Write Access: Ensure application can write to config directory
File Corruption: Check if config file is corrupted
Multiple Instances: Ensure only one instance is running

Invalid Configuration

Problem: Application crashes due to bad configuration

Error on startup
Configuration validation fails

Solutions:

Reset Configuration: Reset to default settings
Check Syntax: Verify configuration file syntax
Remove Bad Settings: Delete problematic configuration entries
Import Backup: Restore from known good configuration
Fresh Start: Delete configuration file and restart

Configuration Conflicts

Problem: Multiple configuration sources conflict

Settings from different sources
Inconsistent behavior

Solutions:

Single Source: Use only one configuration method
Priority Order: Understand configuration precedence
Clear Conflicts: Remove conflicting settings
Environment Variables: Check environment variable settings
Registry Settings: Check Windows registry (if applicable)

🔍 Diagnostic Tools

Built-in Diagnostics

Status Information

Capture Status: Current capture state
Interface Status: Network interface information
Error Count: Number of capture errors
Performance Metrics: CPU and memory usage

Log Analysis

Error Logs: Detailed error information
Debug Logs: Verbose debugging information
Performance Logs: Performance-related data
System Logs: System-level information

External Tools

Network Diagnostics

# Windows
ipconfig /all
netsh interface show interface
netstat -an

# Linux/macOS
ifconfig -a
ip addr show
netstat -an

System Monitoring

# Windows
tasklist /fi "imagename eq DHCPMonitor.exe"
wmic process where name="DHCPMonitor.exe" get processid,workingsetsize

# Linux/macOS
ps aux | grep DHCPMonitor
top -p $(pgrep DHCPMonitor)

Packet Analysis

Wireshark: Detailed packet analysis
tcpdump: Command-line packet capture
Network Monitor: Windows built-in tool