asn: map hosts to their corresponding ASN via WHOIS

usage: asn.py [-h] [--host HOST] [--port PORT] [--update] [--populate]

optional arguments:
  -h, --help   show this help message and exit
  --host HOST  IP address to listen on
  --port PORT  Port to listen on
  --update     Update dataset submodule and create/populate cache
  --populate   Create and populate cache from current dataset

INSTALL

  $ git submodule init
  $ git submodule update --recursive --remote

  $ doas apk add py3-gitpython (Alpine)
  $ ./asn.py --populate
  $ ./asn.py --host 0.0.0.0 --port 4343

optional: forward traffic destined for port 43 (WHOIS default) back to 4343

  $ iptables -A PREROUTING -t nat -p tcp --dport 43 -j REDIRECT --to-ports 4343

USAGE

  $ whois -h whois.jordan.im 1.1.1.1

  IP Address | AS Number | Country | AS Name       | Announcement
  -----------+-----------+---------+---------------+-------------
  1.1.1.1    | 13335     | AU      | CLOUDFLARENET | 1.1.1.0/24

  $ whois -h whois.jordan.im jordan.im

  IP Address        | AS Number | Country | AS Name           | Announcement
  ------------------+-----------+---------+-------------------+---------------
  185.73.44.145     | 8943      | GB      | Jump Networks Ltd | 185.73.44.0/22
  2001:ba8:0:4031:: | 8943      | GB      | Jump Networks Ltd | 2001:ba8::/32