Book Image

Linux Networking Cookbook

By : Agnello Dsouza, Gregory Boyce
5 (1)
Book Image

Linux Networking Cookbook

5 (1)
By: Agnello Dsouza, Gregory Boyce

Overview of this book

Linux can be configured as a networked workstation, a DNS server, a mail server, a firewall, a gateway router, and many other things. These are all part of administration tasks, hence network administration is one of the main tasks of Linux system administration. By knowing how to configure system network interfaces in a reliable and optimal manner, Linux administrators can deploy and configure several network services including file, web, mail, and servers while working in large enterprise environments. Starting with a simple Linux router that passes traffic between two private networks, you will see how to enable NAT on the router in order to allow Internet access from the network, and will also enable DHCP on the network to ease configuration of client systems. You will then move on to configuring your own DNS server on your local network using bind9 and tying it into your DHCP server to allow automatic configuration of local hostnames. You will then future enable your network by setting up IPv6 via tunnel providers. Moving on, we’ll configure Samba to centralize authentication for your network services; we will also configure Linux client to leverage it for authentication, and set up a RADIUS server that uses the directory server for authentication. Toward the end, you will have a network with a number of services running on it, and will implement monitoring in order to detect problems as they occur.
Table of Contents (19 chapters)
Linux Networking Cookbook
About the Author
About the Reviewer

Setting up the physical network

Before we start configuring the networking within Linux, we need to physically connect the systems. The simplest configuration involves connecting the two computers with a single cable, although connecting them to a switch may make more sense for additional expansion. Once physically connected, we need to confirm that they are working as expected.

How to do it…

On each Linux system, use the ip command to check for a network link as shown:

# ip link set dev eth0 up
# ip link show eth0
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000
    link/ether 00:0c:29:6e:8f:ab brd ff:ff:ff:ff:ff:ff

Some people may choose to use ethtool, mii-tool, or mii-diag to perform the same action.

Make sure to run the same command on both the systems, especially if you're connecting to a switch rather than directly connecting the two systems.

How it works…

The first command brings up the network interface card (NIC). This activates the interface and allows it to start the process to check for a network link or electrical connection between the two systems.

Next, the show command gives you a bunch of information about the link. You should see a state showing UP. If it shows DOWN, then you have a link issue of some sort. This could be a disconnected/bad cable, a bad switch, or you forgot to bring up the network interface.