OpenVPN connection test

Published by Tobias Hofmann on

1 min read

After configuring and running both the OpenVPN server and client, it’s a good idea to test if the VPN is working. This involves some tests on both the server and client.

OpenVPN Server

Network Device

After the server is started, a new interface should be created. Run ifconfig to get a list of all available interfaces. In case tun is configured in the conf file as device type, a new interface with name tun0 is created.

ifconfig

Check server log for client connection

In case OpenVPN is started as a service, the log can be found at /var/log/messages. If you start it directly on the command line, the log will be shown on the shell. When a client connects, the log of the server shows the connection information.

tail -f /var/log/messages

The last lines show client1, meaning that the client not only connected, but is also correctly identified as client1. The connection is working.

OpenVPN client

Start OpenVPN and the client will try to connect to the server specified in the client.conf file. Client connecting and receiving IP.

openvpn /etc/openvpn/client.conf
tail -f /var/log/messages

After the connection was established, the client is also creating a new interface named tun0. Here a client named client1 connects and receives the IP 10.8.0.6.

ifconfig

Connection test

Easiest way to test that client and server can talk to each other is to ping both. Just run a ping from the server to the client IP, and from the client to the server IP. For this, the VPN IP address must be used (e.g. 10.8.0.x).

OpenVPN server

Ping client1 from server.

ping 10.8.0.6

OpenVPN client

Ping server from client.

ping 10.8.0.1

Let the world know

Tobias Hofmann

Doing stuff with SAP since 1998. Open, web, UX, cloud. I am not a Basis guy, but very knowledgeable about Basis stuff, as it's the foundation of everything I do (DevOps). Performance is king, and unit tests is something I actually do. Developing HTML5 apps when HTML5 wasn't around. HCP/SCP user since 2012, NetWeaver since 2002, ABAP since 1998.

2 Comments

rdparena · February 2, 2020 at 07:28

Hello,
Is there any portal or website from where I can test my OPVN file ?
It was working for me yesterday night but today morning it’s not working 🙁 I don’t know why
I want to confirm if it is a server side issue or my issue.

hung le · October 4, 2020 at 17:55

hi, I successfully installed my OpenVPN server on CentOS7. The way I tested it was to connect my
laptop to my Iphone, then run the software.
After I connected successfully, I was able to ping all of the machines inside my LAN.
Regards,

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