`127.0.0.1` DNS-resolution is blocked by some ISPs

[rjhuijsman]

(I don't think there's anything we can do about this, but I thought this would be useful to report, as documentation)

While using localhost.direct in a few places worldwide, I've noticed that there's some ISPs that block the DNS-resolution of localhost.direct and any other domain name that resolves to 127.0.0.1. A RIPE Atlas probe showed about 12% of DNS requests for localhost.direct get rejected in some way or another (i.e. not resulting in an A-record with 127.0.0.1).

Asking some friendly DNS operators, they say such filtering is to assuage XSS concerns, and prevent DNS rebinding attacks.

Workarounds that have worked for me:

• Adding the following to my /etc/hosts, so no DNS lookup is required:

127.0.0.1 localhost.direct

• Using a VPN, so that the local ISP can't filter my DNS traffic.

[GloriaOS]

Thanks for reporting this — it's an important edge case to document.

Some ISPs (and DNS resolvers like OpenDNS, some corporate networks) block DNS responses that resolve to 127.0.0.1 or other loopback addresses as a security measure against DNS rebinding attacks. This affects localhost.direct because all records point to 127.0.0.1.

Workarounds (from simplest to most involved):

1. Use /etc/hosts (or C:\\Windows\\System32\\drivers\\etc\\hosts on Windows):

   127.0.0.1 localhost.direct
   127.0.0.1 mysite.localhost.direct
   127.0.0.1 api.localhost.direct
   

   This bypasses DNS entirely and always works.

2. Switch DNS resolver — Use 8.8.8.8 (Google), 1.1.1.1 (Cloudflare), or 9.9.9.9 (Quad9). These typically don't filter loopback responses.

3. Run a local DNS resolver — dnsmasq or unbound on your dev machine can resolve localhost.direct locally without querying upstream.

4. Use a VPN — Some corporate VPNs filter DNS. Disconnecting or using split-tunnel DNS can help.

I'll add a note about this to the README. It's good documentation for developers hitting this issue.

Thanks for flagging it!