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                                     Author: Yassine Aboukir

Notice: The python client is being refactored but you can use web service or its free/paid API at the moment


An autonomous system number (ASN) is a unique number assigned to an autonomous system (AS) by the Internet Assigned Numbers Authority (IANA). An AS consists of blocks of IP addresses which have a distinctly defined policy for accessing external networks and are administered by a single organization

This is a python client which leverages our free API to find the IP space (IPv4 and IPv6) registered and owned by a specific organization.

ASNLookup searches for the organization ASNs and use the latter to find the IP space. You can also use asnlookup client to run port scanning on the IP space using Nmap or Masscan.

Check out for easy use and for the API.


$ git clone && cd Asnlookup
$ pip install -r requirements.txt (or pip3 install -r requirements.txt if you're using Python3)
$ python -o <Organization>

E.g: python -o "Capital One"

Port Scanning

The tool supports port scanning using Nmap or Masscan but requires prior installation on your machine. How to?

  • For Nmap:
On CentOS
$ yum install nmap

- On Debian
$ apt-get install nmap

- On Ubuntu
$ sudo apt-get install nmap

- Mac OS
$ brew install nmap

To scan the IP addresses, append to the command -m arugment for Masscan or -n for Nmap:

$ python -m -o <Organization>

You can also pass your own Nmap/Masscan arguments (Default for nmap: -p 1-65535 -T4 -A -v; default for Masscan: -p0-65535 --rate 200).

$ python -m="<Masscan arguments>" -o <Organization>

Example using Nmap with custom arguments:

$ python -n="--top-ports 65535" -o twitter

It will export the results to a text file in the output directory (E.g: ./output/salesforce.txt) then run Nmap.


For smaller organizations the ASN will usually be that of their ISP whereas the hostname might not. One example of this is, a GitHub IP address. The ASN is AS27357 (Rackspace Hosting), but the hostname is


If you appreciate my work and wish to support it, feel free to:


This project is made for educational and ethical testing purposes only. Usage of this tool for attacking targets without prior mutual consent is illegal. Developers assume no liability and are not responsible for any misuse or damage caused by this tool.


Leverage ASN to look up IP addresses (IPv4 & IPv6) owned by a specific organization for reconnaissance purposes, then run port scanning on it.








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