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Ncrack

Password Attacks

Intermediatehigh risk

Ncrack is a high-speed network authentication cracking tool built by the Nmap team. It supports RDP, SSH, HTTP, SMB, FTP, and more protocols.

Installation

sudo apt install ncrack

Basic Syntax

ncrack [options] <target>

Quick Facts

Full Name
Ncrack
License
GPLv2
Author
Nmap Project (Fyodor)
Written In
C++
Platforms
Linux, Windows, macOS
Category
Network Authentication Cracking
Protocols Supported
12+
Key Feature
Nmap XML integration

Tool Overview

Ncrack is a high-speed network authentication cracking tool built by the Nmap team. It specializes in cracking credentials for connection-oriented protocols like RDP, SSH, SMB, and FTP, with native integration with Nmap scan results.

Created in 2008 as part of the Nmap ecosystem, Ncrack's key advantage is its ability to import targets directly from Nmap XML output. After discovering services with Nmap, you can feed the results directly into Ncrack for credential testing without manual target configuration.

Ncrack supports over 12 protocols and provides precise timing control for stealthy operations. It's designed for speed and efficiency, making it ideal for penetration testing workflows that start with Nmap reconnaissance.

Common Commands

ncrack -hDisplay the help summary with all options and supported modules
ncrack --versionPrint the Ncrack version number and exit
ncrack ssh://10.10.10.10Crack SSH on a host using Ncrack's built-in default credential lists
ncrack -p 22 10.10.10.10Attack a host on a specific port, auto-detecting the SSH service
ncrack -p ssh,rdp,ftp 10.10.10.10Attack multiple services on a host by service name
ncrack -U users.txt -P pass.txt ssh://10.10.10.10Use username and password wordlists against SSH
ncrack --user root,admin ssh://10.10.10.10Supply usernames inline as a comma-separated list
ncrack --pass password123,letmein ftp://10.10.10.10Supply passwords inline as a comma-separated list
ncrack -iL target.txt -p sshRead a list of target hosts from a file and attack SSH
ncrack -p rdp 192.168.1.0/24Attack the RDP service across an entire CIDR subnet
ncrack -f -U users.txt -P pass.txt ssh://10.10.10.10Stop attacking each host as soon as one valid credential is found
ncrack -T4 ssh://10.10.10.10Apply the aggressive timing template for faster attacks
ncrack -g cl=3,cr=2,to=1h ssh://10.10.10.10Set global timing options: concurrent logins, retries, and timeout
ncrack "ssh://10.10.10.10,CL=4,at=6"Set per-service options appended after the service specification
ncrack -oN results.txt ssh://10.10.10.10Write results to a file in normal human-readable format

Step-by-Step Guide

  1. 1Pinpoint the services you intend to evaluate
  2. 2Gather your dictionaries and target accounts
  3. 3Launch the application against the specified host
  4. 4Observe the terminal for successfully recovered passwords
  5. 5Record all validated findings for your audit report

Warnings

Use Cases

Nmap Integration

Import Nmap XML scan results directly for credential testing of discovered services.

RDP Brute Force

Test Windows Remote Desktop services for weak administrative passwords.

SSH Credential Testing

Brute-force SSH services across multiple hosts with Nmap-discovered targets.

SMB Authentication

Test Windows SMB shares for default or weak credentials.

Multi-Protocol Testing

Test multiple protocols simultaneously with a single Ncrack command.

Key Features

Related Tools

Nmap

Information Gathering

Network scanner that discovers services for Ncrack credential testing.

THC Hydra

Password Attacks

More flexible brute-forcer with additional protocols and HTTP form support.

Medusa

Password Attacks

Multi-host brute-forcer for network-wide credential testing campaigns.

Hashcat

Password Attacks

GPU-accelerated offline cracker for hashes extracted from Ncrack-discovered services.

Medusa

Password Attacks

Multi-host parallel scanner for expanding credential testing beyond Ncrack's scope.

Tags

#password-attacks

Output Explanation

Presents successfully validated credentials alongside the relevant IP address and service name.

Ethical Usage Notice

This tool is designed for authorized security testing, educational purposes, and legitimate network administration only. Unauthorized access to computer systems is illegal.