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

Detecting Systems Using Arp-Scan

Some systems choose to block the ICMP traffic, which can result in them not appearing in a ping scan. Any system on your local network, however, must respond to ARP requests if they are going to communicate with additional machines on the network. This gives you an additional option for system enumeration when you are on the local network segment.

How to do it…

First, you install a tool, which will allow you to issue arbitrary arp requests. There are many tools like this, but we are going to use arp-scan, since it allows you to specify entire netblocks rather than just individual IP addresses:

$ sudo apt-get install arp-scan

Now you can actually use the tool to scan your local network segment:

$ sudo arp-scan
Interface: eth0, datalink type: EN10MB (Ethernet)
Starting arp-scan 1.8.1 with 256 hosts (    44:d9:e7:9b:a2:9d    (Unknown)    40:8d:5c:4b:85:d9    (Unknown)