This tool answers the question: am I connected to a (local) network and do I have internet connectivity?

While the question "can this computer reach the Internet?" is quite easily answered by trying to load http://www.google.com in a browser, common network configurations have a number of parameters that may vary between one case of "it's not working" and the next.

networktest aims to be a tool that makes it easy to establish the key network configuration characteristics and get a quick idea of what might be wrong. It is a smoke test of your network setup.

The questions we ask are:

1. Am I connected to any networks? If so, what kind of network are they? Loopback interface? Link-local? Or is it a network that allows me to route packets to the Internet (the kind we want)?
2. What ip addresses do I have on the networks I'm connected to? These are addresses that should be reachable (ie. pingable) from myself.
3. What gateways do I have? A gateway (or router) is a host on my network that allows me to route packets to other networks.
4. Can I reach Internet hosts by ip? If so, my gateway is working.
5. What DNS servers (nameservers) do I have? DNS servers allow me to resolve Internet hostnames to ip addresses.
6. Can I reach Internet hosts by hostname? If so, I have "Internet connectivity" in the common sense.

networktest is written in Go and targets Linux, FreeBSD, OS X, and Windows.

To build:

$ make

To detect IPv4 networking:

$ bin/havenet
 + Scanning for networks...
    <docker0>   172.17.0.0      / 255.255.0.0
    <eth0>      192.168.1.0     / 255.255.255.0
    <wlan0>     192.168.1.0     / 255.255.255.0
 + Detecting ips...
    <lo>        127.0.0.1       / 255.0.0.0         ping: 0.072 ms
    <docker0>   172.17.0.1      / 255.255.0.0       ping: 0.067 ms
    <eth0>      192.168.1.6     / 255.255.255.0     ping: 0.065 ms
    <wlan0>     192.168.1.10    / 255.255.255.0     ping: 0.044 ms
 + Detecting gateways...
    <eth0>      192.168.1.1       ping: 0.706 ms
     ip:        192.168.1.6
     ip:        192.168.1.10
 + Testing internet connection...
    b.root-servers.net.  192.228.79.201   ping: 181.0 ms
 + Detecting dns servers...
    127.0.1.1         ping: 0.052 ms
 + Testing internet dns...
    facebook.com      ping: 315.0 ms
    gmail.com         ping: 37.70 ms
    google.com        ping: 41.10 ms
    twitter.com       ping: 130.0 ms
    yahoo.com         ping: 154.0 ms

To detect IPv6 networking:

$ bin/havenet -6
 + Scanning for networks...
    <lo>                                            ::1 / 128  [scope: host]
    <eth0>                                       fe80:: /  64  [scope: link]
    <wlan0>                                      fe80:: /  64  [scope: link]
 + Detecting ips...
    <lo>                                            ::1 / 128  ping: 0.047 ms
    <eth0>                    fe80::16da:fae1:c9ea:a4b9 /  64  ping: N/A
    <wlan0>                   fe80::762f:fe64:b7c7:7b7a /  64  ping: N/A
 + Detecting gateways...
    none found