resolve-hosts

Resolve list of DNS hostnames.

This is a Python module designed to fit the need of a simple app that can query an input list of DNS names and output their resolved IP addresses. It defaults to using the local system resolver for lookups, but can instead use a list of one or more custom DNS resolvers supplied on the command line.

Installation

This is a setuptools package; install using pip:

pip install resolve-hosts

It's recommended to use pipx for easy setup and isolation:

pipx install resolve-hosts

Usage

The module installs a command line tool called resolve-hosts that should be in your PATH. For a usage overview, see the output of resolve-hosts -h.

Feed it a newline-separated list of names as a parameter. To read from standard input, omit the parameter or use - for the input.

A file with a few sample names to resolve is in the tests/ folder.

Example using the local system resolver:

$ resolve-hosts tests/testnames.txt 
www.example.com             93.184.216.34
blocked.test.on.quad9.net   NXDOMAIN
mxs.mail.ru                 94.100.180.31 217.69.139.150
magnolia.ns.cloudflare.com  172.64.34.214 108.162.194.214 162.159.38.214

The above system is clearly configured to use Quad9 resolvers, as the local resolver returned NXDOMAIN for the test FQDN.

Using specified resolvers and debug output enabled:

$ resolve-hosts -s 8.8.4.4 -s 8.8.8.8 -d tests/testnames.txt 
[DEBUG] configured to use resolver(s): ['8.8.4.4', '8.8.8.8']
[DEBUG] effective resolver address(es): ['8.8.4.4', '8.8.8.8']
www.example.com             93.184.216.34
blocked.test.on.quad9.net   127.0.0.1
mxs.mail.ru                 217.69.139.150 94.100.180.31
magnolia.ns.cloudflare.com  172.64.34.214 108.162.194.214 162.159.38.214

JSON output from data on stdin:

$ resolve-hosts -j < tests/testnames.txt 
{
    "data": [
        {
            "www.example.com": [
                "93.184.216.34"
            ]
        },
        {
            "blocked.test.on.quad9.net": [
                "NXDOMAIN"
            ]
        },
        {
            "mxs.mail.ru": [
                "217.69.139.150",
                "94.100.180.31"
            ]
        },
        {
            "magnolia.ns.cloudflare.com": [
                "162.159.38.214",
                "108.162.194.214",
                "172.64.34.214"
            ]
        }
    ]
}