Testing a Connection

1 hour
  • 4 Learning Objectives

About this Hands-on Lab

In this hands-on lab, you will need to troubleshoot connectivity issues between `Client1` ( and `Server1` ( You will need to determine why the website at is unreachable, and prep the host to make sure connectivity is in place to permit SSL traffic once it’s configured.

Learning Objectives

Successfully complete this lab by achieving the following learning objectives:

Confirm the problem.

On Client1 (

Confirm that the problem exists by curling the headers of from

curl -I

Confirm, and maybe resolve, Apache’s status.

On Server1 (

Verify a service is listening on port 80:

ss -lntp | grep :80

If nothing is listening, check if Apache is running:

systemctl status httpd

Start Apache if necessary:

systemctl start httpd

Did that resolve the problem?

Check firewall rules.

On Server1 (

Verify that the firewall is configured to permit http traffic:

firewall-cmd --list-services

If http isn’t present, it will need to be added:

firewall-cmd --permanent --add-service=http

And the firewall rules will need to be reloaded to take effect:

firewall-cmd --reload

Verify that the problem is resolved.

Permit https traffic in the firewall and verify.

On Server1 (

You will need to open port 443 in the firewall. You can do it with:

# firewall-cmd --permanent --add-service=https

And then reloading the firewall config with this:

# firewall-cmd --reload

You will need to facilitate listening on port 443 from Server1 ( You can do this by installing the nmap-ncat package for CentOS:

# yum install nmap-ncat

And then using it to listen on port 443:

# nc -l -p 443

On Client1 (

Install telnet:

$ yum install -y telnet

You can verify that 443 is accessible by using telnet:

$ telnet 443

Additional Resources

The website is down!

You need to troubleshoot and resolve connectivity issues between Client ( and Server1 ( Once those are resolved, Server1 needs to be configured to permit port 443 traffic. Confirm that connectivity from Client1 to Server1 over 443 is working.

What are Hands-on Labs

Hands-on Labs are real environments created by industry experts to help you learn. These environments help you gain knowledge and experience, practice without compromising your system, test without risk, destroy without fear, and let you learn from your mistakes. Hands-on Labs: practice your skills before delivering in the real world.

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