Responder: Install, configure, exploit

Responder: Install, configure, exploit


To provide a comprehensive guide on using Responder from scratch, including installation on different operating systems and a real-life scenario, let’s break down the process into detailed steps. Responder is a powerful network tool for penetration testing, particularly effective in poisoning, sniffing, and exploiting network protocols. It’s widely used in cybersecurity assessments to identify and exploit vulnerabilities within network services.

Installation and Environment Setup

On Kali Linux

Kali Linux, a preferred choice for security professionals, includes Responder as part of its testing toolkit, simplifying the installation process.

  1. Update System Repositories:
    Open a terminal and run:
sudo apt-get update
  1. Install Responder:
    Since Responder is included in Kali’s repositories, you can install it directly using:
sudo apt-get install responder
  1. Verify Installation:
    Check if Responder is correctly installed by running:
responder -h

This command displays the help menu, indicating a successful installation.

On Windows

Installing Responder on Windows requires manual setup, as it’s primarily designed for Unix-like environments.

  1. Download Python:
    Ensure Python is installed on your system. If not, download and install it from the official Python website.
  2. Clone Responder:
    Use Git to clone the Responder repository:
git clone

If Git is not installed, download the ZIP file directly from the GitHub repository and extract it.

  1. Install Dependencies:
    Navigate to the Responder directory and install the required Python dependencies:
pip install -r requirements.txt
  1. Run Responder:
    Within the Responder directory, execute:
python -h

On Other Unix-like Systems

The process is similar to that on Kali Linux, involving updating the system’s package repositories, cloning the Responder GitHub repository, and installing any dependencies via Python’s pip tool.


Responder can be used in various modes, such as analyzing network traffic, poisoning, and exploiting vulnerabilities. Here’s a basic command to start Responder and listen on all interfaces:

sudo responder -I eth0 -wrf

This command tells Responder to listen on the eth0 interface, with -w enabling WPAD (Web Proxy Auto-Discovery) poisoning, -r enabling LLMNR (Link-Local Multicast Name Resolution) poisoning, and -f forcing authentication for NBT-NS (NetBIOS Name Service) poisoning.

More Options
–versionShow program’s version number and exit.
-h, –helpShow this help message and exit.
-A, –analyzeAnalyze mode. Allows seeing NBT-NS, BROWSER, LLMNR requests without responding.
-I eth0, –interface=eth0Specify the network interface to use; ‘ALL’ can be used as a wildcard for all interfaces.
-i, –ip= the local IP to use (only for OSX).
-6, –externalip6=2002:c0a8:f7:1:3ba8:aceb:b1a9:81edPoison all requests with a different IPv6 address than Responder’s one.
-e, –externalip= all requests with a different IP address than Responder’s one.
-b, –basicReturn a Basic HTTP authentication. Default: NTLM.
-d, –DHCPEnable answers for DHCP broadcast requests, injecting a WPAD server in the DHCP response. Default: False
-D, –DHCP-DNSInject a DNS server in the DHCP response; otherwise, a WPAD server will be added. Default: False
-w, –wpadStart the WPAD rogue proxy server. Default value is False
-u UPSTREAM_PROXY, –upstream-proxy=UPSTREAM_PROXYSpecify an upstream HTTP proxy for the rogue WPAD Proxy to use for outgoing requests (format: host:port).
-F, –ForceWpadAuthForce NTLM/Basic authentication on wpad.dat file retrieval, possibly causing a login prompt. Default: False
-P, –ProxyAuthForce NTLM (transparently)/Basic (prompt) authentication for the proxy; WPAD doesn’t need to be ON. Default: False
–lmForce LM hashing downgrade for Windows XP/2003 and earlier. Default: False
–disable-essForce ESS downgrade. Default: False
-v, –verbos
Increase verbosity.

Real-life Scenario

Scenario Setup:
  • Company: Acme Corp, a construction company with an internal network.
  • Attacker (IT Professional): Alex, a cybersecurity consultant conducting a penetration test.
  • Target: Acme Corp’s internal network, specifically unsecured Windows devices.

Objective: Identify and exploit misconfigured network services using Responder.

  1. Preparation:
    – Alex sets up Responder on a Kali Linux machine connected to Acme Corp’s network.
    – Ensures all necessary permissions and ethical hacking agreements are in place.
  2. Discovery:
    – Alex runs Responder in analysis mode to identify potential targets and vulnerable services.
    – Identifies several devices responding to LLMNR and NBT-NS queries.
  3. Exploitation:
    – Alex configures Responder to poison LLMNR and NBT-NS queries, forcing devices to authenticate against the attacker’s machine.
    – Captures hashed credentials transmitted over the network.
  4. Post-Exploitation:
    – Alex uses tools like John the Ripper or Hashcat to crack the captured hashes. (Other tools allow passing hashes to authenticate, no cracking needed)
    – Gains access to several user accounts, demonstrating the risk of using default configurations and weak passwords.
  5. Reporting:
    – Documents the findings, including the methods used and the vulnerabilities exploited.
    – Provides Acme Corp with recommendations for securing their network, such as disabling LLMNR, NBT-NS, WINRM, Remote Registry, etc where possible, and enforcing strong password policies.
  6. Remediation:
    – Acme Corp gets in touch with CyberBlip to contract Professional IT Services and gets a Certified Engineer to mitigate all vulnerabilities and build a stronger IT Infrastructure.

This scenario illustrates the practical application of Responder in a penetration testing context, highlighting the importance of regular security assessments and adherence to best practices in network configuration and password policies.


Responder is a versatile and powerful tool for cybersecurity professionals, offering capabilities for network protocol poisoning, sniffing, and exploitation. Its implementation across various operating systems, including Kali Linux and Windows, demonstrates its flexibility and utility in a wide range of security assessment scenarios. The tool’s effectiveness in identifying and exploiting vulnerabilities within network services underscores the importance of thorough network security practices and the need for regular assessments.

As cybersecurity threats continue to evolve, tools like Responder remain essential for professionals looking to safeguard their digital environments against potential attacks. It’s important for users to stay informed about the latest developments and best practices related to Responder and similar cybersecurity tools, ensuring they are well-prepared to address and mitigate security risks.


For further reading and a detailed guide on installing and using Winget, consider visiting the following resources:

  • The official documentation by Laurent Gaffie provides comprehensive details on using Responder for network security assessments, available at
  • “Kali Linux – An Ethical Hacker’s Cookbook, 2nd Edition” by Himanshu Sharma, published by Packt Publishing in 2019, includes insights into Responder among other tools for security assessments.
  • Justin Seitz’s “Black Hat Python: Python Programming for Hackers and Pentesters,” published by No Starch Press in 2014, offers foundational knowledge in Python for network attacks, relevant to understanding Responder’s capabilities.
  • “Penetration Testing: A Hands-On Introduction to Hacking” by Georgia Weidman, from No Starch Press in 2014, introduces penetration testing fundamentals, including techniques core to Responder’s functionality.
  • William Stallings’ “Network Security Essentials: Applications and Standards,” published by Pearson in 2017, provides foundational network security knowledge applicable to Responder’s environment.
  • Cybersecurity blogs and websites like Krebs on Security, Dark Reading, and the SANS Institute blog are excellent for articles on the latest in cybersecurity tools and techniques, including Responder.
  • The official Python documentation, available at, is crucial for understanding the scripting aspect of cybersecurity tools like Responder.
  • “The Hacker Playbook 3: Practical Guide To Penetration Testing” by Peter Kim, published by Secure Planet LLC in 2018, discusses practical penetration testing techniques, including those relevant to Responder’s use.

These sources provide a solid foundation for understanding Responder’s application in cybersecurity, offering both technical depth and practical insights.

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