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Connection Issues

If you have deployed the Platform on more than one host you may need to make changes to firewalls in order for the application to connect successfully. Firewalls can block connections to the KX Control Application from the Web Tier (AppServer/Tomcat) if it is deployed on a separate host.

Connection Test

If you are having problems with your Dashboards connecting to the Control backend it is sometime best to simplify the problem. This can be done by using netcat (nc) to take the platform stack out of the equation and debug at a connection level.

To run this test shutdown the platform and all its components.

On the Control host run the following command to listen for TCP connections. The port used should be the port you are running Control on (grep DELTACONTROL_PORT delta.profile).

$ nc -l 2001

On your AppServer host attempt to connect to the listening process on the Control host as follows:

$ nc <controlhost> 2001

The host name above should be the hostname/ip-address where you are running the nc -l command.

If a firewall is blocking the connection the command above will fail with a connection refused error (Ncat: Connection refused.) or hang and eventually time out. If this happens then you need to try and diagnose what’s blocking the connection.

If the connection is successful, then you can should be able to enter text in the AppServer nc terminal and when you hit <Return> it should appear on the Control terminal. If the connection is successful but you are still having issues with the Dashboards then you need to reach out to support.

Software Firewalls

The most common issues we see with fresh installations is that a software firewall (iptables or firewalld) is running on the deploy host.

You can check the status of firewalld by running the following:

$ systemctl status firewalld
firewalld.service - firewalld - dynamic firewall daemon
      Loaded: loaded (/usr/lib/systemd/system/firewalld.service; enabled)
      Active: active (running) since Sat 2013-04-06 22:56:59 CEST; 2 days ago
    Main PID: 688 (firewalld)
      CGroup: name=systemd:/system/firewalld.service

If the firewall is active you can disable and stop it by running the following commands as root:

$ systemctl disable firewalld
$ systemctl stop firewalld

If you don’t have root access you will need to contact your unix team to either disable firewalld for you or add rules for the ports you are trying to connect to.

Network Firewalls

If you have confirmed that a software firewall is not blocking connections on a certain port then you should talk to your network team and ensure that there are no network firewalls running which may block access to your application.