Tool Documentation:

ncrack Usage Example

Use verbose mode (-v), read a list of IP addresses (-iL win.txt), and attempt to login with the username victim (–user victim) along with the passwords in a dictionary (-P passes.txt) using the RDP protocol (-p rdp) with a one connection at a time (CL=1):

root@kali:~# ncrack -v -iL win.txt --user victim -P passes.txt -p rdp CL=1

Starting Ncrack 0.6 ( ) at 2018-12-01 09:54 EDT

rdp:// finished.
Discovered credentials on rdp:// 'victim' 's3cr3t'

Packages and Binaries:


Ncrack is a high-speed network authentication cracking tool. It was built to help companies secure their networks by proactively testing all their hosts and networking devices for poor passwords. Security professionals also rely on Ncrack when auditing their clients. Ncrack was designed using a modular approach, a command-line syntax similar to Nmap and a dynamic engine that can adapt its behaviour based on network feedback. It allows for rapid, yet reliable large-scale auditing of multiple hosts.

Ncrack’s features include a very flexible interface granting the user full control of network operations, allowing for very sophisticated bruteforcing attacks, timing templates for ease of use, runtime interaction similar to Nmap’s and many more. Protocols supported include RDP, SSH, http(s), SMB, pop3(s), VNC, FTP, and telnet.

Be sure to read the Ncrack man page ( to fully understand Ncrack usage.

Installed size: 1.66 MB
How to install: sudo apt install ncrack

  • libc6
  • libgcc-s1
  • libssl3t64
  • libstdc++6

Network authentication cracking tool

root@kali:~# ncrack -h
Ncrack 0.7 ( )
Usage: ncrack [Options] {target and service specification}
  Can pass hostnames, IP addresses, networks, etc.
  Ex:,,; 10.0.0-255.1-254
  -iX <inputfilename>: Input from Nmap's -oX XML output format
  -iN <inputfilename>: Input from Nmap's -oN Normal output format
  -iL <inputfilename>: Input from list of hosts/networks
  --exclude <host1[,host2][,host3],...>: Exclude hosts/networks
  --excludefile <exclude_file>: Exclude list from file
  Can pass target specific services in <service>://target (standard) notation or
  using -p which will be applied to all hosts in non-standard notation.
  Service arguments can be specified to be host-specific, type of service-specific
  (-m) or global (-g). Ex: ssh://,at=10,cl=30 -m ssh:at=50 -g cd=3000
  Ex2: ncrack -p ssh,ftp:3500,25,ssl
  -p <service-list>: services will be applied to all non-standard notation hosts
  -m <service>:<options>: options will be applied to all services of this type
  -g <options>: options will be applied to every service globally
  Misc options:
    ssl: enable SSL over this service
    path <name>: used in modules like HTTP ('=' needs escaping if used)
    db <name>: used in modules like MongoDB to specify the database
    domain <name>: used in modules like WinRM to specify the domain
  Options which take <time> are in seconds, unless you append 'ms'
  (milliseconds), 'm' (minutes), or 'h' (hours) to the value (e.g. 30m).
  Service-specific options:
    cl (min connection limit): minimum number of concurrent parallel connections
    CL (max connection limit): maximum number of concurrent parallel connections
    at (authentication tries): authentication attempts per connection
    cd (connection delay): delay <time> between each connection initiation
    cr (connection retries): caps number of service connection attempts
    to (time-out): maximum cracking <time> for service, regardless of success so far
  -T<0-5>: Set timing template (higher is faster)
  --connection-limit <number>: threshold for total concurrent connections
  --stealthy-linear: try credentials using only one connection against each specified host 
    until you hit the same host again. Overrides all other timing options.
  -U <filename>: username file
  -P <filename>: password file
  --user <username_list>: comma-separated username list
  --pass <password_list>: comma-separated password list
  --passwords-first: Iterate password list for each username. Default is opposite.
  --pairwise: Choose usernames and passwords in pairs.
  -oN/-oX <file>: Output scan in normal and XML format, respectively, to the given filename.
  -oA <basename>: Output in the two major formats at once
  -v: Increase verbosity level (use twice or more for greater effect)
  -d[level]: Set or increase debugging level (Up to 10 is meaningful)
  --nsock-trace <level>: Set nsock trace level (Valid range: 0 - 10)
  --log-errors: Log errors/warnings to the normal-format output file
  --append-output: Append to rather than clobber specified output files
  --resume <file>: Continue previously saved session
  --save <file>: Save restoration file with specific filename
  -f: quit cracking service after one found credential
  -6: Enable IPv6 cracking
  -sL or --list: only list hosts and services
  --datadir <dirname>: Specify custom Ncrack data file location
  --proxy <type://proxy:port>: Make connections via socks4, 4a, http.
  -V: Print version number
  -h: Print this help summary page.
  SSH, RDP, FTP, Telnet, HTTP(S), Wordpress, POP3(S), IMAP, CVS, SMB, VNC, SIP, Redis, PostgreSQL, MQTT, MySQL, MSSQL, MongoDB, Cassandra, WinRM, OWA, DICOM
  ncrack -v --user root localhost:22
  ncrack -v -T5
  ncrack -v -iX ~/nmap.xml -g CL=5,to=1h

Updated on: 2024-May-23