Filters the ARIN IP address delegations by a country code and parses it into CIDR notation. Wrote it based on http://blog.erben.sk/2014/01/28/generating-country-ip-ranges-lists/

country-ip-addr.sh

#!/usr/bin/env sh
# based on http://blog.erben.sk/2014/01/28/generating-country-ip-ranges-lists/

# change accordingly
country_code='US';

# please reference the proper registry
#	United States, Canada, several parts of the Caribbean region, and Antarctica: http://ftp.arin.net/pub/stats/arin/delegated-arin-extended-latest
#	Europe, Russia, the Middle East, and Central Asia: http://ftp.ripe.net/ripe/stats/delegated-ripencc-latest
#	Africa: http://ftp.afrinic.net/pub/stats/afrinic/delegated-afrinic-latest
#	Asia, Australia, New Zealand, and neighboring countries: http://ftp.apnic.net/pub/stats/apnic/delegated-apnic-latest
#	Latin America and parts of the Caribbean region: http://ftp.lacnic.net/pub/stats/lacnic/delegated-lacnic-latest
delegations_url='http://ftp.arin.net/pub/stats/arin/delegated-arin-extended-latest'

curl $delegations_url --silent | awk -v country_code=$country_code -F '|' 'BEGIN { pattern=country_code"\\|ipv4"; } $0 ~ pattern {print $4 "/" (32-log($5)/log(2)) }';