Troubleshooting Application...

Sometimes a User Reports that the Application is Not working or The Application is Down.... This Does Not always Means that the application itself is stopped. The problem can be anywhere between the Client and the application server.. For EX ::- The server may be reachable through PING, but a particular application port such as ( 80, 443, 8080 or 22 ) may still not be Accessible...

Our Basic Flow...

Client/Bastion server >>> Basic Network Connectivity >>> Ping Test >>> OCI security Rules >>> Server Firewall >>> Application Port >>> Application/Services...

The Main Purpose of this Lab is to Check Each layer one by one Instead of Directly assuming that the application is Down..

Step by step Troubleshooting...

Firstly, checking Normal basic Connectivity...

ping <application_server_ip>

192.168.0.178

Secondly, checking Port Connectivity...

sudo dnf install telnet -y

Jumped into the Application Server..

Added NAT Gateway in Spoke Vcn...

Now, installing the Application HTTP in the Amazon (Application Server)...

sudo dnf install httpd -y

httpd -v

TESTING..

telnet <application_server_ip> <Port_Number>

192.168.0.178 80

 ssh -i/root/ssh-keys/private_key.pem [email protected]

systemctl status firewalld

The firewall is active. Now we will check if it is allowing HTTP by using...

sudo firewall-cmd --list-all

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

sudo firewall-cmd --reload

sudo firewall-cmd --list-all

Now switching to the bastion_server and Checking it's working or Not...

telnet 192.168.0.178 80

sudo systemctl status httpd

sudo systemctl start httpd

sudo systemctl status httpd

sudo netstat -plan | grep ':80'

telnet 192.168.0.178 80

Finally, It's Connected...

THANKYOU!