aslookup

Python client for IP to ASN lookup services

aslookup is a client utility for two of the public IP/AS query services operated by the following organizations:

• Shadowserver -- https://www.shadowserver.org/wiki/pmwiki.php/Services/IP-BGP
• Team Cymru -- http://www.team-cymru.org/IP-ASN-mapping.html

The client implements both a simple Python module (aslookup) as well as a CLI utility (as-lookup). The lookups are done using DNS with asynchronous processing for improved performance when handling multiple IP addresses.

Both IPv4 and IPv6 addresses are supported. The client also maintains a listing of IP networks which are unroutable internet addresses, typically in special use RFC ranges. In this way it can both filter out addresses from queries which are a waste of time, as well as provide context to the user on the address.

Performance

Starting with version 2.0.0, aslookup uses asynchronous DNS lookups to improve performance when processing multiple IP addresses. The tool automatically processes multiple addresses concurrently (up to 15 simultaneous requests by default) while maintaining the same CLI interface and output format.

Installation

The app has been tested on Python 3.

It's best to install the program into a Python virtualenv. If you will only use the command line interface, the recommended way to install it is using pipx:

pipx install aslookup

If you will use aslookup as a library, you'll instead want to install it using pip in your target Python environment:

python3 -m pip install aslookup

Usage

Python module

The Python module defaults to querying the Team Cymru data service. The desired service may be specified by passing the service parameter to get_as_data.

from aslookup import get_as_data
ip = "8.8.8.8"
get_as_data(ip, service="shadowserver")

CLI script

It is possible to provide multiple IP addresses as arguments to the script, or to send them as a list on standard input, in which cases the script loops over them and returns output on separate lines. When providing invalid IP addresses as arguments, the script reports the problem on standard error and exits with an error. When providing input on stdin, the error is reported on standard output but execution is not aborted.

as-lookup 8.8.8.8 9.9.9.9
as-lookup 2001:4860:4860::8888 2001:4860:4860::8844

or:

as-lookup < ipaddrs.txt

Test data

A list of test values for the script is included in the file tests/test_input.txt. This can be useful to validate included IP prefix classifications and see the output format.

as-lookup < tests/test_input.txt