How to Use traceroute on Ubuntu | Installation, Options, and Error Troubleshooting Explained in Detail

By 佐川 直弘 | Naohiro Sagawa (運営者)

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1. What is traceroute? A Fundamental Tool for Network Path Analysis

Overview of traceroute

traceroute is a tool that tracks the path of a network connection and identifies the routers that data packets pass through before reaching their destination. By using this tool, you can pinpoint where network delays or failures occur. It is particularly useful for network administrators and IT professionals troubleshooting network issues.

How traceroute Works

traceroute sends ICMP (Internet Control Message Protocol) or UDP (User Datagram Protocol) packets and records the responses from each router along the path. This process allows users to see every node the data passes through.

How It Works: Step-by-Step

1. Send packets with a low TTL (Time to Live) value.
2. As packets pass through routers, the TTL decreases. When it reaches zero, the router returns a response.
3. Record the router’s IP address and response time based on the received responses.
4. Increase the TTL value step by step and resend packets until the destination is reached.

Benefits of traceroute

• Identify Network Failures: Quickly locate where delays or packet loss occur along the network route.
• Visualize Routing Paths: Understand the route packets take, including which countries or regions they pass through.
• Analyze Performance: Measure response times at each hop to evaluate network performance.

Comparison with Other Tools

traceroute is specialized for tracking network paths but is often compared to tools like ping and mtr. While ping checks connectivity to a single host, traceroute visualizes the entire network route. mtr combines both traceroute and ping functionalities, allowing real-time monitoring of network paths.

2. How to Install traceroute on Ubuntu

Checking If traceroute is Installed

traceroute may not be pre-installed on Ubuntu. To check whether it is installed, run the following command in the terminal:

traceroute --version

If the command displays version information, traceroute is already installed. If you see “command not found,” you need to install it.

Installation Steps for traceroute

Follow these steps to install traceroute:

1. Update package information
   Run the following command to update the package list:

   sudo apt update

2. Install traceroute
   Run the following command to install traceroute:

   sudo apt install traceroute

During installation, if prompted, press “Y” to proceed.

3. Verify installation
   Once installed, run the following command to check if traceroute is working:

   traceroute --version

If the installation is successful, it will display version details.

Permission Considerations

Since traceroute performs network-related operations, some options require sudo. For example, when using ICMP packets, execute the command with sudo:

sudo traceroute -I example.com

Troubleshooting Installation Issues

Installation may fail due to the following issues:

1. Network Connection Issues
   If your internet connection is unstable, the installation may stop midway. Check your connection and try again.
2. Package Management Issues
   If the package cache is corrupted, clear it using the following commands and then retry:

   sudo apt clean
   sudo apt update
   sudo apt install traceroute

3. Basic Commands and Options for traceroute

Basic Syntax of traceroute

The basic syntax for using traceroute is as follows:

traceroute [options] <target hostname or IP address>

Executing this command displays the routers the packets pass through, their IP addresses, and the latency for each hop.

Basic Usage Example

To trace the route to a target hostname (e.g., google.com), run:

traceroute google.com

This command provides the following information:

• IP addresses of the routers along the path
• Response time (in milliseconds) for each hop
• Error messages (e.g., * if the packet couldn’t reach a node)

Key Options Explained

traceroute includes various options to enhance network analysis.

-I: Use ICMP Echo Packets

By default, traceroute uses UDP packets. This option switches to ICMP echo packets.

traceroute -I example.com

Example Use Case: Some firewalls block UDP but allow ICMP, making this option useful for bypassing restrictions.

-T: Use TCP Packets

Uses TCP protocol, which is useful for troubleshooting web servers.

traceroute -T example.com

Example Use Case: Analyzing connections to web servers (ports 80 or 443).

-p: Specify Port Number

Allows specifying a port for UDP or TCP packets.

traceroute -p 8080 example.com

Example Use Case: Checking traffic related to a specific service.

-n: Do Not Resolve Hostnames

Skips hostname resolution and displays only IP addresses, speeding up execution.

traceroute -n example.com

-m: Set Maximum Hops

Limits the number of hops (default is 30).

traceroute -m 20 example.com

-q: Set Probe Count

Specifies the number of packets sent per hop (default is 3).

traceroute -q 1 example.com

4. Advanced Uses of traceroute: Practical Network Diagnostics

Using traceroute in Real-World Scenarios

traceroute is highly effective for identifying network issues and analyzing performance. Below are some practical scenarios where traceroute can be useful.

Identifying the Cause of Network Latency

If your network is slow, traceroute can help determine where the latency occurs. Follow these steps:

1. Trace the route to the target server

   traceroute example.com

2. Check where the delay occurs
   Analyze response times for each hop. If a specific hop has significantly higher latency, that node may be the cause of the delay. Example output:

   1  192.168.1.1 (192.168.1.1)  1.123 ms  1.456 ms  1.789 ms
   2  10.0.0.1 (10.0.0.1)  2.456 ms  2.678 ms  2.789 ms
   3  192.0.2.1 (192.0.2.1)  150.789 ms  151.123 ms  151.456 ms

• Key Insight: If hop #3 has a sudden increase in latency, there may be a problem near 192.0.2.1.

5. Common Errors When Running traceroute and How to Fix Them

Common Errors in traceroute

Sometimes, running traceroute results in errors or unexpected behavior. Below are some common issues and their solutions.

command not found Error

Cause:

• traceroute may not be installed.

Solution:

• Check if traceroute is installed and, if not, install it using the following command:

  sudo apt update
  sudo apt install traceroute

* * * Appears in Output

Cause:

• Packets may be blocked by a firewall or network policy.
• Certain routers or devices do not respond to traceroute requests.

Solution:

1. Use Different Protocols

• Use ICMP echo packets:
  traceroute -I example.com
• Use TCP packets:
  traceroute -T example.com

1. Check with Network Administrators

• Some organizations or ISPs block specific packets, so it may be necessary to contact the network administrator.

6. Frequently Asked Questions (FAQ)

Q1. What is the difference between traceroute and ping?

A:

• traceroute:
  Shows the entire network path and identifies where delays or failures occur.
• ping:
  Checks if a single host is reachable and measures round-trip time, but does not provide routing details.

Q2. Why does traceroute stop before reaching the destination?

A:
Possible reasons include:

1. Firewall Restrictions
   Some routers block response packets.
2. Router Configuration
   Certain routers are set not to send responses.
3. Packet Loss
   High network congestion can cause packet drops.

Solutions:

• Try using ICMP (-I option) or TCP (-T option) instead of UDP.

7. Conclusion

The Importance of traceroute

traceroute is an essential tool for network troubleshooting and path analysis. By using it effectively, you can identify network flow issues and pinpoint delays efficiently.

Key Takeaways from This Article

1. Understanding traceroute’s Functionality

• traceroute visualizes packet travel paths and identifies delays or failures.

1. Installing traceroute on Ubuntu

• It can be installed easily using sudo apt install traceroute.

1. Basic Commands and Useful Options

• Supports ICMP, TCP, hop count adjustment, and more.

1. Advanced Applications

• Useful for diagnosing network delays, packet loss, and firewall restrictions.

1. Handling Common Errors

• Solutions for * * * and command not found errors.

1. Frequently Asked Questions Answered

• Clarified differences between traceroute and ping, and how to handle incomplete routes.

Making the Most of traceroute

traceroute is widely used from personal network troubleshooting to corporate IT infrastructure management. It is especially useful for:

• Investigating unstable internet connections
• Verifying firewall and router settings
• Analyzing global network routes

Next Steps

Try running traceroute on your own network to apply what you’ve learned. Practicing will help reinforce the concepts covered in this article.

Final Thoughts

Network diagnostics is a fundamental IT skill. Mastering traceroute will give you a strong advantage in troubleshooting and managing network infrastructure effectively.