[dns-operations] Oddness with Cloudfare authoritative servers

Wed Sep 22 23:49:05 UTC 2021

On Wed, Sep 22, 2021 at 7:26 PM Adam David <adam.vallee at gmail.com> wrote:

> This does not seem to be a DNS resolution/misconfiguration issue on
> Cloudflare's end.
>
> https://172.64.80.1/ provides an error message (as it should) indicating
> it is a CloudFlare IP. If you can't see that in a web browser, then the
> issue is local to your network.
>

Yes, 172.64.80.1 is a CF address, but it was being returned for
deltamath.com.
Doing a GET / over TLS with the host set to deltamath.com  was giving a 403
Forbidden:
HTTP/1.1 403 Forbidden
Server: cloudflare
Date: Wed, 22 Sep 2021 18:44:15 GMT
Content-Type: text/html
Content-Length: 151
Connection: keep-alive
CF-RAY: 692daefc1ffd542b-YYZ

<html>
<head><title>403 Forbidden</title></head>
<body>
<center><h1>403 Forbidden</h1></center>
<hr><center>cloudflare</center>
</body>
</html>

The other address handed out all worked fine.
So:
1: it is a DNS issue and they shouldn’t have handed out that address for
that name or
2: that machine was borked.

W

> The main causes that I gather would be:
>
> 1. There was a temporary cache propagation issue on CF's network. (Still
> not a DNS issue.)
> 2. Your IT department is using 172.0.0.0/9 or possibly even 172.0.0.0/8
> where they intended to use 172.16.0.0/12 (RFC1918 IP space). This would
> block access to the netblock belonging to Cloudflare and you would have
> difficulty accessing thousands of websites.
>                                  Side Note: 172.64.0.0/13 belongs
> to AS13335.
>
> You should always start with your IT department.
> If you are a Cloudflare customer, contact them directly.
> If you are a DeltaMath customer, then you need to contact them directly.
>
> Sincerely,
>
> Adam Vallee
>
>
>
> On Wed, Sep 22, 2021 at 4:03 PM Brown, William <wbrown at e1b.org> wrote:
>
>> From: dns-operations <dns-operations-bounces at dns-oarc.net> On Behalf Of
>> Erik Stian Tefre
>> Sent: Wednesday, September 22, 2021 3:38 PM
>> To: dns-operations at lists.dns-oarc.net
>> Subject: Re: [dns-operations] Oddness with Cloudfare authoritative servers
>>
>> > Possibly not a DNS issue at all, but something like this:
>>
>> > https://community.cloudflare.com/t/revil-ransomware/301435
>>
>> > (Executive summary: One Cloudflare IP being blocked by a firewall
>> because of a different and misbehaving Cloudflare customer who happened to
>> serve malicious content from that same IP.)
>>
>> > Regards,
>> > Erik
>>
>> Interesting.  The real issue I am experiencing is that I am getting
>> inconsistent responses from nominally the same authoritative server.  It
>> just so happens that when we get 172.64.80.1 as the answer it fails.  I
>> would prefer to get the correct answer so students can use the online
>> educational resource the district is paying for.
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Perhaps they really do strive for incomprehensibility in their specs.
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