CreateReactApp Refused Me

on technology

Today, I tried to open https://create-react-app.dev and look for some manual. But I hit the wall; I couldn’t open it. The browser gave me the below error message:

This site can’t be reached
create-react-app.dev refused to connect.
Try:

Checking the connection
Checking the proxy and the firewall
ERR_CONNECTION_REFUSED

I flipped the link to my wife and she confirmed that she was able the access the link. Neither reconnecting Wi-Fi nor Logging out solved the problem.

I needed to fix it, cause I need to read the document! Errrrr. So, I started my debugging process.

First, I needed to confirm it’s not my browser’s problem. So, I used curl:

curl -vvvv https://create-react-app.dev
*   Trying 127.0.0.1...
* TCP_NODELAY set
* Connection failed
* connect to 127.0.0.1 port 443 failed: Connection refused
* Failed to connect to create-react-app.dev port 443: Connection refused
* Closing connection 0
curl: (7) Failed to connect to create-react-app.dev port 443: Connection refused

The curl output showed the same result with more information; the domain got resolved to my localhost: 127.0.0.1.

How weird!

I doubled-checked through ping and traceroute. Bad luck as well.

$ ping create-react-app.dev
PING create-react-app.dev (127.0.0.1): 56 data bytes
64 bytes from 127.0.0.1: icmp_seq=0 ttl=64 time=0.050 ms
64 bytes from 127.0.0.1: icmp_seq=1 ttl=64 time=0.117 ms

$ traceroute create-react-app.dev
traceroute to create-react-app.dev (127.0.0.1), 64 hops max, 52 byte packets
 1  localhost (127.0.0.1)  0.472 ms  0.042 ms  0.037 ms

However, the dig and nslookup didn’t think the domain should be 127.0.0.1:

$ dig create-react-app.dev
...
create-react-app.dev.	299	IN	A	104.24.106.133
create-react-app.dev.	299	IN	A	104.24.107.13

$ nslookup create-react-app.dev
Server:		8.8.4.4
Address:	8.8.4.4#53

Non-authoritative answer:
Name:	create-react-app.dev
Address: 104.24.107.133
Name:	create-react-app.dev
Address: 104.24.106.133

So, it must be somewhere on my localhost overwriting the dns resolving results.

The first place I suspected was /etc/hosts.

$ cat /etc/hosts
127.0.0.1 localhost

Well, it seems this file didn’t give any instruction to amend the dns resolving results.

Then, I found there was a directory that was really suspicious: /etc/resolver. What’s under this directory?

$ ls /etc/resolver
dev

What the hell?

$ cat /etc/resolver/dev
# Lovingly generated by Pow
nameserver 127.0.0.1
port 20560

Hmm, I think I found the root cause. I removed the file and cleaned the dns cache:

$ ps aux|grep dns
_mdnsresponder   64913   0.0  0.0  4381768   6468   ??  Ss   10:59AM   0:00.18 /usr/sbin/mDNSResponder
$ sudo kill -9 64913

Hooray, it worked!

$ curl -I https://create-react-app.dev
HTTP/2 200

Then I realized that I installed Pow several years ago and configured it for aliasing any domain *.dev to my localhost. I re-readed Pow’s documentation and found the warning:

Adding top-level domains like “.com” to POW_DOMAINS can be hazardous to your health! In the (likely) event that at some point you lock yourself out of these domains, you will be unable to reach important remote addresses like github.com (where you can find the source code) and S3 (where Pow’s installation and uninstallation scripts are hosted). Do not panic! Delete the files Pow has created in /etc/resolver/ and DNS activity will return to normal. (You can safely use POW_EXT_DOMAINS for these domains instead.)

It applies to *.dev domain.

Lesson Learned

  • You can tamper DNS results via /etc/hosts + /etc/resolver.
  • Launching a local DNS server may be a better approach.
  • The list of top-level domains is expanding.