Bash URL to ASN lookup - https://blog.jiayu.co/2018/10/quick-url-to-asn-lookups/

asn.sh

asn() {
  if [ -z "$1" ]
  then
    echo "usage: asn url" 1>&2
    return 1
  fi

  ips=$(dig $DIG_ARGS +short $1)
  if [ -z "$ips" ]
  then
    echo "dig $1 failed" 1>&2
    return 1
  fi
  
  # convert ips to array
  iparr=($ips)
  
  # if there is more than one ip address,
  # use the bulk netcat interface
  # else use the whois interface
  if (( ${#iparr[*]} > 1 ))
  then
    printf "begin\nverbose\n$ips\nend\n" | netcat whois.cymru.com 43
  else
    whois -h whois.cymru.com " -v $ips"
  fi
}

url-to-asn-lookup.md

URL to ASN lookup

Usage

$ source asn.sh
$ asn github.com
Bulk mode; whois.cymru.com [2018-09-29 04:12:30 +0000]
36459   | 192.30.253.113   | 192.30.253.0/24     | US | arin     | 2012-11-15 | GITHUB - GitHub, Inc., US
36459   | 192.30.253.112   | 192.30.253.0/24     | US | arin     | 2012-11-15 | GITHUB - GitHub, Inc., US
$ asn google.com
AS      | IP               | BGP Prefix          | CC | Registry | Allocated  | AS Name
15169   | 216.58.199.142   | 216.58.199.0/24     | US | arin     | 2012-01-27 | GOOGLE - Google LLC, US
$