Azure VM : Can't conect to HTTPS Endpoint

Question

_{Wednesday, July 22, 2015 8:47 AM}

I have created a HTTPS-443 stand alone end point in a Virtual Machine. Now when I try to telnet the Public IP Address of that VM at Port 443, I can't. It fails with error :- Couldn't open connection to host , on port 443: connect failed.

A quick response would be highly appreciated.

All replies (7)

_{Wednesday, July 29, 2015 9:28 AM ✅Answered}

Hi 3novsan,

I would suggest you check if telnet on any other endpoints mapping to the same VM works fine like PowerShell , RDP / SSH .

Also would like to check if you have tried deleting and recreating the endpoints?

Regards.

_{Wednesday, July 22, 2015 9:19 AM}

Hi 3novsan,

Thanks for posting here.

There could be many reasons, but the most common are:

1. Firewall blocking access between the machines (also check local firewalls)
2. Port not open on the destination machine

After checking for firewalls and that the port is open, use telnet to connect to the ip/port to test connectivity. This removes any potential issues from your application.

The error means the OS of the listening socket recognized the inbound connection request but chose to intentionally reject it. Assuming an intermediate firewall is not getting in the way, there are only two reasons (that I know of) for the OS to reject an inbound connection request. One reason has already been mentioned several times - the listening port being connected to is not open. There is another reason that has not been mentioned yet - the listening port is actually open and actively being used, but its backlog of queued inbound connection requests has reached its maximum so there is no room available for the inbound connection request to be queued at that moment. The server code has not called accept() enough times yet to finish clearing out available slots for new queue items. Wait a moment or so and try the connection again. Unfortunately, there is no way to differentiate between "the port is not open at all" and "the port is open but too busy right now". They both use the same generic error code.

Connection refused means that the port you are trying to connect to is not actually open.

So either you are connecting to the wrong IP address, or to the wrong port, or the server is listening on the wrong port, or is not actually running.

A common mistake is not specifying the port number when binding or connecting in network byte order.

Check at the server side that it is listening at the port 2080. First try to confirm it on the server machine by issuing telnet to that port:

telnet localhost 2080

If it is listening, it is able to respond.

Although it does not seem to be the case for your situation, sometimes a connection refused error can also indicate that there is an ip address conflict on your network. You can search for possible ip conflicts by running:

 arp-scan -I eth0 -l | grep <ipaddress>

and

arping <ipaddress>

Hope this helps;

_{Wednesday, July 22, 2015 9:57 AM}

I can telnet 443 from another Azure VM using Internal address of VM. But not from internet. Wondering how can we troubleshoot it.

_{Wednesday, July 22, 2015 11:18 AM}

Hi,

Thanks for replying back.

Could you please Check if ISP is blocking the public internet?

And would suggest you to use PSping for troubleshooting.

Regards.

_{Thursday, July 23, 2015 6:21 AM}

ISP is not blocking Public Internet as I can telnet 443 to other IP Addresses. Also Here is the output of PSPING :

C:\psping mail.3novsan.com:443

PsPing v2.01 - PsPing - ping, latency, bandwidth measurement utility
Copyright (C) 2012-2014 Mark Russinovich
Sysinternals - www.sysinternals.com

TCP connect to 207.46.237.63:443:
5 iterations (warmup 1) connecting test:
Connecting to 207.46.237.63:443 (warmup): This operation returned because the ti
meout period expired.
Connecting to 207.46.237.63:443: This operation returned because the timeout per
iod expired.
Connecting to 207.46.237.63:443: This operation returned because the timeout per
iod expired.
Connecting to 207.46.237.63:443: This operation returned because the timeout per
iod expired.
Connecting to 207.46.237.63:443: This operation returned because the timeout per
iod expired.

TCP connect statistics for 207.46.237.63:443:
  Sent = 4, Received = 0, Lost = 4 (100% loss),
  Minimum = 0.00ms, Maximum = 0.00ms, Average = 0.00ms

_{Tuesday, July 28, 2015 11:48 AM}

Hi,

I would like you to check the below link.

https://azure.microsoft.com/en-in/documentation/articles/virtual-networks-acl-powershell/

And remove ACL.

Regards.

_{Wednesday, July 29, 2015 3:49 PM}

It was resolved after deleting and recreating the endpoint.