Script to generate an nginx deny rule for a specific ASN

generate-nginx-asn-deny.sh

#!/usr/bin/env bash

# saner programming env: these switches turn some bugs into errors
set -o errexit -o pipefail -o noclobber -o nounset

# Script to generate deny rules for a specific ASN, e.g. Alibaba's https://ipinfo.io/AS45102.
# This provides a more up to date rule set than relying on a separate external tool.

ASN="${1?you must specify the ASN}"
whois -h whois.radb.net -- "-i origin $ASN" > "$ASN.txt"
sed -nE 's/route:\s*([0-9]{1,3}(\.[0-9]{1,3}){3}\/[0-9]+).*/deny \1;/p' "$ASN.txt"  > "deny_$ASN.conf"
# Remove duplicates.
awk -i inplace '!seen[$0]++' "deny_$ASN.conf"