php cURL to localhost returns permission denied on an open port

Question

I'm getting a permission denied error when trying to make a cURL request with the php cURL library to localhost on port 4321. This will hopefully be really easy or obvious for someone who's run into this before.

I'm able to make the identical cURL request from another system on the local area network to the production server. For example, if on another system on the local area network I make a request using the function below where $host='http://192.168.1.100:4321' then everything works exactly like it should. If I run on the system itself where $host='http://localhost:4321' or $host='http://127.0.0.1:4321' or $host='::1:4321' then I get a cURL error of "Permission Denied"

The function I wrote for my very simple request is:

function makeRequest($host,$data){
    $ch = curl_init();
    curl_setopt($ch,CURLOPT_URL, $host);
    curl_setopt($ch,CURLOPT_POSTFIELDS, $data);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);
    $result = json_decode(curl_exec($ch),true);
    if(!empty(curl_error($ch))){
        $result = print_r(curl_error($ch).' - '.$host);
    }
    curl_close($ch);
    return $result;
}

The system is a centos 7 server. Running firewall-cmd --list-all shows my open ports

ports: 443/tcp 80/tcp 4321/tcp

If you have some idea, or need me to check a setting don't hesitate to ask.

EDIT The hosts file looks like

127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4

EDIT2

When I use commandline curl against the same port everything comes back alight.

 /]$ curl -v localhost:4321
* About to connect() to localhost port 4321 (#0)
*   Trying ::1...
* Connected to localhost (::1) port 4321 (#0)
> GET / HTTP/1.1
> User-Agent: curl/7.29.0
> Host: localhost:4321
> Accept: */*
>
< HTTP/1.1 200 OK
< Accept-Ranges: bytes
< Cache-Control: no-cache, no-store, must-revalidate
< Content-Length: 774....

A couple of suggestions are 1) to check your hosts file and see if localhost is mapped to 127.0.0.1 and, if not, to add this entry, and 2) to run curl from the command line using the -v switch to check the full output and gain better insight. If you run curl on the command line, consider dumping the output here so we can see what's going on. — B. Fleming
– B. Fleming, Commented Oct 10, 2017 at 17:05
Noticed that your first (successful) try had http:// in front of it while the failed ones didn't. Is that a typo? cURL needs to operate on http(s) — apokryfos
– apokryfos, Commented Oct 10, 2017 at 17:10
It's sort of a typo. I tried first with the http:// and then later without it. — Altimus Prime
– Altimus Prime, Commented Oct 10, 2017 at 17:16
Could you show us the exact error you're getting? This can help narrow down the issue. — B. Fleming
– B. Fleming, Commented Oct 10, 2017 at 17:40
so, who is listening on that port ? some kind of http server ? if you are truly getting a permission denied (ie not a connection refused) , then the issue may be with the listening process. — YvesLeBorg
– YvesLeBorg, Commented Oct 10, 2017 at 17:40

theduck · Accepted Answer · 2019-11-25 07:21:42Z

20

I found the answer to the problem at: Getting permission denied while Posting xml using Curl?

The problem is SELinux and the solution is to run:

sudo setsebool httpd_can_network_connect 1

It doesn't make sense to me that I could use the php cURL library to access every other website in the world, but not localhost on a different port, while I was able to access the localhost from command line cURL.

edited Nov 25, 2019 at 7:21

theduck

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answered Oct 11, 2017 at 1:22

Altimus Prime

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2 Comments

jems Over a year ago

use this user@host /]$ sudo setsebool httpd_can_network_connect 1 remove = from above syntax. this works for me.

Salem Over a year ago

This error stopped WP from running on my website, thanks it really works

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