Today we're going to explore the fine fun world of network discovery and find out who is on our network without ever leaving our comfortable chairs.

Without any special hardware or reconfiguration, it can capture live data going in and out over any of your box's network interfaces: Ethernet, WiFi, PPP, loopback, even USB.

Wireshark is a network protocol analyzer (or "packet sniffer") that can be used for network analysis, troubleshooting, software development, education, etc. This guide shows how to install and use it on an Ubuntu 9.10 desktop to analyze the traffic on the local network card.

Anonymity and deniability in distributing information are two of the goals of the GNUnet project. At its heart, GNUnet is a mechanism to share content with others without revealing who generated the content or who accessed it. It also provides intermediate nodes in the network with the ability to deny knowledge of the contents of any traffic they forward because they are unable to decrypt it.

This guide shows how to install and configure Smokeping on Ubuntu 9.04 to monitor network latency. SmokePing is a deluxe latency measurement tool. It can measure, store and display latency, latency distribution and packet loss. SmokePing uses RRDtool to maintain a longterm data-store and to draw pretty graphs, giving up to the minute information on the state of each network connection.

Open source software and widespread instrumentation have lowered the costs of producing IT management software. Open source systems management companies are using the free nature of an open source product, coupled with the cheap distribution the Web enables, to boot-strap their businesses.

You probably rely on the services on your own private network -- wikis, mail servers, Web sites, and other applications you've installed. What happens when you have to leave the friendly confines of your network?

Part one of a five part post series on setting up Linux and Unix servers securely.