EC2 HTTPS connection requests from the instance itself are refused!!!

Thank you for your reply.

We do not use any private SSL certificate and we use ACM certificate added to the load balancer.

Our Load Balancer has been set up as follows:

Actually, our application uses the HTTP client (working with CURL) to send a post HTTPS request to itself (server to server request but the requester and the receiver servers are the same), so it actually uses the instance public IP like requests coming from the browser.

The application level error is as follows:

The results of

curl --verbose https://lms.3dyazdir.xyz

:

• Trying 3.125.46.128:443...
• connect to 3.125.46.128 port 443 failed: Connection refused
• Failed to connect to lms.3dyazdir.xyz port 443 after 0 ms: Connection refused
• Closing connection 0 curl: (7) Failed to connect to lms.3dyazdir.xyz port 443 after 0 ms: Connection refused

The instance info are as follows:

Ensure that the DNS resolution for "lms.3dyazdir.xyz" is working correctly. You can use the nslookup or dig command to check the DNS resolution.

nslookup lms.3dyazdir.xyz

or

dig lms.3dyazdir.xyz

also, If you are using HTTPS (port 443), make sure that the SSL/TLS certificate is valid and properly configured on the server. An SSL handshake failure could result in a connection refused error.

try to get more information via curl --verbose https://lms.3dyazdir.xyz

if nothing found here, Identify the SG of instance and then, Add a rule that allows traffic on the desired port(s) for the services you want to access. For example, if you want to allow HTTP (port 80) and HTTPS (port 443), you can add rules like these:

Type: HTTP, Source: 0.0.0.0/0 (Allow traffic from any IP) Type: HTTPS, Source: 0.0.0.0/0 (Allow traffic from any IP) and If you want to allow traffic only from the instance itself, you can use the private IP of the instance or the security group ID as the source.

Hi again,

The result of

nslookup lms.3dyazdir.xyz

Server: 127.0.0.53 Address: 127.0.0.53#53

Name: lms.3dyazdir.xyz Address: 3.125.46.128

Also I use the following certificate at lms.3dyazdir.xyz :

When I run the following CURL request from the server SSH terminal (Self-request), I get the following error:

ubuntu@ip-172-31-18-0:/var/www/nohut/lms$ curl https://lms.3dyazdir.xyz/api/user -H "Accept: application/json"

curl: (7) Failed to connect to lms.3dyazdir.xyz port 443 after 0 ms: Connection refused

But when I run the same CURL request from the terminal of my PC, I get a response!

okhtay@okhtay-Inspiron-24-5410-All-in-One:~$ curl https://lms.3dyazdir.xyz/api/user -H "Accept: application/json"

{"message":"Unauthenticated."}

So, clearly self-requests are blocked by the server. When the server sends requests to itself, the firewall stops the server to respond!

Can you use loopback address 127.0.0.1 or localhost as the target in your cURL command ?

ubuntu@ip-172-31-18-0:/var/www/nohut/lms$ curl 127.0.0.1:80/api/user -H "Accept: application/json"