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I am having a strange issue on my newly installed Amazon Ec2 ubuntu 16.04 LTS server.

I have a server with ip (10.129.29.46) in a VPC which has the following ports open 80, 443, 11300 and 9000. Port 80 and 443 are open to public via Amazon Security Groups whereas port 9000 and 11300 accepts incoming connections from local network only.

There are about 20 servers in same VPC subnet. Most of the servers in the subnet are able to ping and telnet

telnet 10.129.29.46 11300

Trying 10.129.29.46...
Connected to 10.129.29.46.
Escape character is '^]'.

Now when I ping the same server from a newly created Ubuntu 16.04 instance I am able to telnet port 22

ubuntu@ip-10-129-29-50:~$ telnet 10.129.29.46 22

Trying 10.129.29.46...
Connected to 10.129.29.46.
Escape character is '^]'.
SSH-2.0-OpenSSH_6.6.1p1 Ubuntu-2ubuntu2.4

But when I telnet port 11300 and 9000 they won't respond. Below is the output:

ubuntu@ip-10-129-29-50:~$ telnet 10.129.29.46 11300
Trying 10.129.29.46...
telnet: Unable to connect to remote host: Connection timed out

I checked the UFW firewall is disabled.

My first question is, what is potentially causing it not to telnet on those port? And my second question is, is there a way print telnet debug messages something similar to ssh -vvv so I can debug and see what's going on?

Aftab Naveed
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1 Answers1

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I'm not an expert on AWS (more used to Digital Ocean) but I think your problem could be to do with Amazon's network infrastructure having an ACL?

As to your second question about saving the response I think using bash you can output the response to a command into a file like so:

telnet 10.219.29.46 11300 > ~/Documents/telnetExample.txt

Hope your issue gets resolved!

Louis
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