Allow ping to specify IPv4, IPv6 or 'any protocol'

[ajmas]

Allow for ping options to specify the type of ping to be done. For example, somethings like:

opts = {
    ipv4: true,
    ipv6: true
};

ping.sys.probe(host, function(isAlive) {

}, opts);

If something like this can already be done, please could you indicate the correct way in the documentation.

[FlorianWendelborn]

A workaround could be to use the IPv4 or IPv6 address directly instead of the domain.

[BlessJah]

Not necessarily. Some systems may have separate ping and ping6 commands (it requires further investigation).

[elad]

I'd like to have this functionality too. Submitted PR #67.

@ajmas it needs a single toggle (e.g. v6) otherwise you could potentially specify both and I think that's odd behavior.

[mondwan]

Close this issue and please give us a hand on #79 so that we can better support the ipv6.

Thanks :)