August 2015
Intermediate to advanced
364 pages
7h 35m
English
Content preview from Mastering OpenVPNBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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Analyzing OpenVPN traffic by using tcpdump
The low-level networking tool tcpdump, or its GUI equivalent Wireshark, is a last resort tool for troubleshooting network issues and network performance. In this section, we will walk through the process of capturing and analyzing the encrypted network traffic produced by OpenVPN.
First, we set up our standard OpenVPN network using the basic-udp configuration files. On the client, there is also a web server running. We will use the wget command on the server side to retrieve a file from the web server so that we can look at the resulting network traffic.
We run tcpdump on the Ethernet interface and capture the network traffic while doing a wget outside the tunnel:
wget -O /dev/null https://CLIENT-IP/test1 ...Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.