Book Image

Troubleshooting OpenVPN

By : Eric F Crist
Book Image

Troubleshooting OpenVPN

By: Eric F Crist

Overview of this book

OpenVPN, the most widely used open source VPN package, allows you to create a secure network across systems, keeping your private data secure. Connectivity and other issues are a pain to deal with, especially if they are impacting your business. This book will help you resolve the issues faced by OpenVPN users and teach the techniques on how to troubleshoot it like a true expert. This book is a one stop solution for troubleshooting any issue related to OpenVPN. We will start by introducing you to troubleshooting techniques such as Packet Sniffing, Log Parsing, and OpenSSL. You will see how to overcome operating system specific errors. Later on, you will get to know about network and routing errors by exploring the concepts of IPv4 and IPv6 networking issues. You will discover how to overcome these issues to improve the performance of your OpenVPN deployment. By the end of the book, you will know the best practices, tips, and tricks to ensure the smooth running of your OpenVPN.
Table of Contents (16 chapters)

Duplicate client certificates


By default, OpenVPN expects each remote client to connect using a unique certificate for identification and encryption purposes. The common name (CN), is used to generate configuration options, identify a persistent IP (--ifconfig-pool-persist), and CCD (--client-config-dir) entries. In addition, startup scripts may use the CN to generate dynamic routes, firewall rules, and other access policies.

For the majority of general road-warriors, special routing, and firewall rules are not the norm. In this scenario, the user connects to the VPN, is given an IP address from the server, and they will then have access to the resources of the corporate network. More advanced configurations may provide differing pushed routes or IP assignments in varying subnets.