[URGENT] EC2 OFTP Port 6619 connection refused

Question

Hello,

I have been using the EC2 server since 2021 without any issues connecting with my vendors via OFTP on port 6619. Recently, I received an email from one of our vendors reporting that their connection to our server was refused. When I investigated, I found that I am also unable to connect to the server using Telnet or an OFTP connection on port 6619.

I checked the Security Group's inbound rule, which is set as follows:
Port: 6619
Protocol: TCP
Source: 0.0.0.0/0
Purpose: OFTP
Additionally, I ran sudo ufw status on the EC2 instance, and it confirmed that port 6619 is allowed from anywhere.

I’m not sure what is causing this issue, especially since I can still access the server via SSH on port 22 without any problems.

Any assistance in diagnosing and resolving this issue would be greatly appreciated.

Thank you

Steve_M · Accepted Answer

Re: the additional info you added as a comment, according to the man page for **nmap(1)**

> A closed port is accessible (it receives and responds to Nmap probe packets), but there is no application listening on it.

So it's worth checking your application is up.

Does the output of `sudo netstat -tulpn | grep -w 6619` show that there is a process listening on the port?

Brainer · Answer

I fixed it. 
There was no service listening to the port. 
It turned out that the OFTP software had a problem.
Thank you for your support.

[URGENT] EC2 OFTP Port 6619 connection refused

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