How to get IP ranges used by company

If you really do want to find out all of the IP addresses for an organization it's relatively straight forward as long as they have their own ASN.  If you don't already know the organization's ASN you can get hold of MaxMind's organization CSV file and do a bit of processing, and then grep for the organization you're interested in.

Here is how to do it ?

Downloading the file

Download this file:

wget http://download.maxmind.com/download/geoip/database/asnum/GeoIPASNum2.zip

Enumerating the ASN

Enumerate the ASN of company from file

cat files/GeoIPASNum2.zip |gunzip | cut -d"," -f3 | sed 's/"//g' | sort -u | grep -i COMPANY_NAME

Eg:
cat files/GeoIPASNum2.zip |gunzip | cut -d"," -f3 | sed 's/"//g' | sort -u | grep -i twitter

Getting IP ranges

Fire up whois Command

whois -h whois.radb.net -- '-i origin <ASN> ' | grep -Eo "([0-9.]+){4}/[0-9]+"

Eg:
whois -h whois.radb.net -- '-i origin AS394434' | grep -Eo "([0-9.]+){4}/[0-9]+"


and you will have the list of ip ranges they are using.

Thank you.