Using MTR Tool for Network Troubleshooting

Overview

MTR (My Traceroute) is a powerful network diagnostic tool that combines the functionality of ping and traceroute to provide detailed insights into network performance and connectivity issues. This article guides you through installing, using, and interpreting MTR results for effective troubleshooting.

Prerequisites

• A system with administrative or sudo privileges.
• Access to a terminal or command-line interface.
• Basic understanding of network concepts (e.g., IP addresses, latency, packet loss).

Installation

On Linux

Most Linux distributions include MTR by default or in their package repositories.

Ubuntu/Debian

1. Update the package list:
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   sudo apt update

    

    
2. Install MTR:
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   sudo apt install mtr

    

    

CentOS/RHEL

1. Enable the EPEL repository (if not already enabled):
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   sudo yum install epel-release

    

    
2. Install MTR:
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   sudo yum install mtr

    

    

On macOS

1. Install Homebrew (if not already installed):
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   /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

    

    
2. Install MTR:
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   brew install mtr

    

    
3. Note: On macOS, MTR may require sudo to run due to raw socket access.

On Windows

MTR is not natively supported on Windows, but you can use WinMTR, a Windows port of MTR.

1. Download WinMTR from https://sourceforge.net/projects/winmtr/ or another trusted source.
2. Extract the ZIP file and run WinMTR.exe.

Running MTR

Basic Command

To run MTR, use the following syntax in a terminal:

Replace [destination] with the target hostname or IP address (e.g., google.com or 8.8.8.8).

Common Options

• -r or --report: Generate a report after a specified number of cycles.
• -c [count] or --report-cycles [count]: Set the number of pings per hop (default is 10).
• -n or --no-dns: Display IP addresses instead of resolving hostnames.
• -s [size] or --psize [size]: Set packet size in bytes.
• -4 or -6: Force IPv4 or IPv6, respectively.
• -i [seconds] or --interval [seconds]: Set interval between pings (default is 1 second).
• --tcp: Use TCP instead of ICMP.
• --udp: Use UDP instead of ICMP.

Example:

This runs MTR in report mode, sending 10 pings to each hop on the route to google.com.

Interactive Mode

Running mtr [destination] without options starts MTR in interactive mode, displaying real-time results. Press the following keys to interact:

• d: Toggle display mode (e.g., cycle through statistics).
• n: Toggle DNS resolution.
• q: Quit MTR.

On Windows (WinMTR)

1. Open WinMTR.exe.
2. Enter the target hostname or IP in the "Host" field.
3. Click "Start" to begin tracing.
4. Click "Stop" to end and save results if needed.

Interpreting MTR Output

MTR provides a table with the following columns:

• Host: The IP address or hostname of each hop.
• Loss%: Percentage of packets lost at each hop (0% is ideal).
• Snt: Number of packets sent.
• Last: Latency of the last packet (in milliseconds).
• Avg: Average latency across all packets.
• Best: Lowest (best) latency recorded.
• Wrst: Highest (worst) latency recorded.
• StDev: Standard deviation of latency, indicating consistency (lower is better).

Key Indicators

• Packet Loss: High loss (e.g., >5%) at a hop suggests issues like congestion or hardware failure.
• High Latency: Consistently high Avg or Last values indicate delays at that hop.
• Jitter: High StDev values suggest unstable connections.
• No Response: A hop showing ??? or no data may indicate a firewall blocking ICMP or a routing issue.

Troubleshooting Steps

1. Identify Packet Loss:
   • Run mtr -r -c 100 [destination] to collect more data.
   • Look for hops with significant packet loss (>5–10%).
   • If loss occurs at the destination but not intermediate hops, the issue may be with the target server.
2. Analyze Latency:
   • Compare Avg, Best, and Wrst columns. Large differences suggest instability.
   • Check if high latency starts at a specific hop, indicating a bottleneck.
3. Test Different Protocols:
   • Use --tcp or --udp to test if issues are protocol-specific (e.g., mtr --tcp [destination]).
4. Compare IPv4 and IPv6:
   • Run mtr -4 [destination] and mtr -6 [destination] to identify IP version-specific issues.
5. Check DNS:
   • Use -n to disable DNS resolution and confirm if issues are DNS-related.
6. Escalate to ISP or Network Admin:
   • If issues occur outside your network (e.g., beyond your router), share MTR results with your ISP or network administrator.
   • Export results using mtr -r -c 100 [destination] > mtr-report.txt.

Best Practices

• Run MTR for at least 30–100 cycles (-c 30 or -c 100) for reliable data.
• Test during different times to identify intermittent issues.
• Avoid running MTR as a background process for extended periods, as it may consume resources.
• If testing a specific service (e.g., web server), use --tcp or --udp to match the service’s protocol.
• On macOS or Linux, use sudo if MTR fails to run due to permission issues.

Common Issues and Solutions

• "Permission Denied" Error:
  • Run MTR with sudo (e.g., sudo mtr google.com) to allow raw socket access.
• No Route to Host:
  • Verify the destination hostname/IP is correct.
  • Check local firewall or network restrictions.
• High Latency at First Hop:
  • Indicates issues with your local router or connection. Restart the router or contact your ISP.
• Intermittent Loss:
  • Run MTR multiple times to confirm. Check for network congestion or hardware issues.

Saving and Sharing Results

• Save MTR output to a file:
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  mtr -r -c 100 [destination] > mtr-report.txt

   

   
• On WinMTR, click "Export TEXT" to save results.
• Share the text file with your ISP or network team for further analysis.

Additional Notes

• MTR may be blocked by firewalls or rate-limited by some networks. If results are incomplete, try --tcp or --udp.
• For persistent issues, combine MTR with other tools like ping, traceroute, or nslookup for a comprehensive diagnosis.
• On Windows, WinMTR may not support all MTR options (e.g., --tcp). Use Linux/macOS for advanced features.

Conclusion

MTR is an essential tool for diagnosing network issues, providing detailed insights into packet loss, latency, and routing problems. By following this guide, you can effectively use MTR to troubleshoot connectivity issues and communicate findings to relevant parties.

For further assistance, contact your network administrator or ISP with your MTR results.