Use OpenDNS instead of the slow ipv6-test.com API

[MechMK1]

Grabbing my external IPv4 address didn't work for me with the default setup, because IPv4 was horrendously slow (causing it to timeout every time), whereas OpenDNS was near-instant.

[glensc]

doesn't seem to always answer. tried in 3 places, 2 of them failed.

[MechMK1]

doesn't seem to always answer. tried in 3 places, 2 of them failed.

It's weird, I had that problem with ipv6-test.com, and opendns worked fine for me. It could be a temprary outage as well?

[glensc]

it does not seem temporary problem. home dsl works 100%, other permenent line connections fail 100%, also i think may have more firewall related issues than http. because direct connection to dns servers are not always not allowed. your command forces to use resolver1.opendns.com udp/53

examples:

➔ time timeout 1 dig myip.opendns.com @resolver1.opendns.com +short
x.y.z.c

real	0m0.065s
user	0m0.004s
sys	0m0.009s

➔ time dig myip.opendns.com @resolver1.opendns.com +short

real    0m0.018s
user    0m0.003s
sys     0m0.007s

$ time dig myip.opendns.com @resolver1.opendns.com +short

; <<>> DiG 9.14.6 <<>> myip.opendns.com @resolver1.opendns.com +short
;; global options: +cmd
;; connection timed out; no servers could be reached

real    0m18.011s
user    0m0.006s
sys     0m0.005s

[MechMK1]

It never occured to me that direct communication to DNS servers could be an issue, but that is indeed troublesome.

I guess the best way would be to implement several ways and iterate through them, picking the best possible method, but that's way outside the scope of my PR.

[dustinkirkland]

Thanks for this. But I think we're going to need something more robust...

[MechMK1]

I understand. I didn't expect DNS queries to be a problem. Perhaps offering it as an alternative via a config option could work? I'll see what I can do

[paulocoghi]

If it's useful, Cloudflare DNS is a solid option, reliable and fast. Resolvers:

1.1.1.1
1.0.0.1
2606:4700:4700::1111
2606:4700:4700::1001