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
Credits
About the Author
About the Reviewer
www.PacktPub.com
Preface
Index

Identifying operating systems


In addition to identifying services running on servers, nmap can additionally attempt to identify the Operating System running on a particular system. This type of scan typically requires at least one open and one closed port to be reached.

How to do it...

Use nmap –O to do OS fingerprinting:

$ sudo nmap -n -O 192.168.1.205 -p 22,80
Starting Nmap 6.40 ( http://nmap.org ) at 2016-05-20 17:57 EDT
Nmap scan report for 192.168.1.205
Host is up (0.013s latency).
PORT   STATE  SERVICE
22/tcp closed ssh
80/tcp open   http
MAC Address: 74:DA:EA:F3:FF:07 (Unknown)
Device type: general purpose
Running: Linux 2.6.X|3.X
OS CPE: cpe:/o:linux:linux_kernel:2.6 cpe:/o:linux:linux_kernel:3
OS details: Linux 2.6.32 - 3.2
Network Distance: 1 hop

OS detection performed. Please report any incorrect results at http://nmap.org/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 2.63 seconds

How it works…

Nmap's OS detection code works by issuing various packet types to services...