NETWORKING IN LINUXNETWORKING IN LINUX

WHAT IS LINUX..?

• Freely implemention of UNIX-like Kernel.

• Free & Open source Software.

• Developed by Linus Torvalds in 1991.

Evolution of Linux Kernel

First Linux Version 0.01 released on May 14th 1991.

Second Linux Version 1.0 released on March 14th 1994.

Third Linux Version 2.0 released on June 1996.

Fourth Linux Version 2.2 released on Jan 1999.

Fifth Linux Version 2.4 released in January 2001.

Latest Linux Version 2.6 released in December 2003.

SELinux

• Security Enhanced Linux• Clean separation of policy from

enforcement• Independent of specific policies and

policy languages• Caching of access decisions for

efficiency• # Support for policy changes

Basic Networking ToolsPING:anshu@anshu-desktop:~$ ping www.google.comPING www.l.google.com (209.85.153.104) 56(84) bytes of

data.64 bytes from im-in-f104.google.com (209.85.153.104): icmp_seq=1 ttl=247 time=98.4 ms64 bytes from im-in-f104.google.com (209.85.153.104): icmp_seq=2 ttl=247 time=84.7 ms--- www.l.google.com ping statistics ---

3 packets transmitted, 2 received, 33% packet loss, time 1998msrtt min/avg/max/mdev = 84.769/91.601/98.434/6.839 ms

• NETSTAT :

anshu@anshu-desktop:~$ netstat -rKernel IP routing table

Destination Gateway Genmask Flags MSS Window irtt Iface

122.50.192.0 * 255.255.252.0 U 0 0 0 eth0

link-local * 255.255.0.0 U 0 0 0 eth0

• IFCONFIG :

ifconfig is used to configure the kernel-resident network interfaces. It is used at boot time to set up interfaces as necessary. After that, it is usually only needed when debugging or when system tuning is needed.

NSLOOKUP:anshu@anshu-desktop:~$ nslookup

www.google.comServer: 202.62.224.2Address: 202.62.224.2#53Non-authoritative answer:www.google.com canonical name = www.l.google.com.Name: www.l.google.comAddress: 209.85.153.104

TRACEROUTE:

anshu@anshu-desktop:~$ traceroute www.iacr.ac.in

traceroute to www.iacr.ac.in (206.105.196.68), 30 hops max, 40 byte packets

NMAP:

anshu@anshu-desktop:~$ nmap -A www.iacr.ac.in

Starting Nmap 4.53 ( http://insecure.org ) at 2008-07-24 00:01 ISTSCRIPT ENGINE: rpcinfo.nse is not a file.SCRIPT ENGINE: Aborting script scan.

Interesting ports on www.silicon.ac.in (206.105.196.68):

Internet ServicesInternet Services

TelnetTelnet::

anshu@anshu-desktop:~$ telnet www.iacr.ac.inTrying anshu@anshu-desktop:~$ telnet www.iacr.ac.inTrying 206.105.196.68...206.105.196.68...

Connected to Connected to www.iacr.ac.inwww.iacr.ac.in..

Escape character is '^]'.Escape character is '^]'.

CentOS release 4.4 (Final)CentOS release 4.4 (Final)

Kernel 2.6.9-42.0.10.ELsmp on an i686Kernel 2.6.9-42.0.10.ELsmp on an i686

login: login:

• Secure Shell (SSH):

anshu@anshu-desktop:~$ ssh www.iacr.ac.inThe authenticity of host 'www.iacr.ac.in (206.105.196.68)' can't be established.RSA key fingerprint is 5a:9b:1d:e8:d7:ad:a8:cf:58:66:49:77:1f:24:13:88.Are you sure you want to continue connecting (yes/no)? yes

Warning: Permanently added 'www.iacr.ac.in,206.105.196.68' (RSA) to the list of known hosts.

anshu@www.iacr.ac.in's password:

• File Transfer Protocol (FTP):

anshu@anshu-desktop:~$ ftp ftp.kernel.orgConnected to pub.us.kernel.org.220 Welcome to ftp.kernel.org.Name (ftp.kernel.org:saurabh): anonymous331 Please specify the password.Password:

• Secure Copy (SCP):

The syntax for scp is:

scp user@host:file1 user@host file2

• Secure File Transfer Program (SFTP):

The syntax for sftp is:

sftp user@host: file file

• FINGER:

anshu@anshu-desktop:~$ finger anshu

Login: anshu Name: anshu Kumar

Directory: /home/anshu Shell: /bin/bash

On since Wed Jul 23 09:06 (IST) on tty7 from :0

On since Wed Jul 23 12:12 (IST) on pts/0 from :0.0

No mail.

No Plan.

• The SAMBA Server:

• Their own logins on all the home windows boxes while having their files on the Linux box appear to be located on a new Windows drive.

• Shared access to printers on the Linux box

• Shared files accessible only to members of their Linux user group.

• The Web Server Apache:

Apache, is a web server notable for playing a key role in the initial growth of the World Wide Web. Apache was the first viable alternative to the Netscape Communications Corporation web server (currently known as Sun Java System Web Server), and has since evolved to rival other Unix-based web servers in terms of functionality and performance.

• Network File System Protocol :

• Linux data storage disks contain files stored in file systems with a standardized directory structure. New disks are added by attaching, or mounting, the directories of their file systems to a directory of an already existing file system. This in effect makes the new hard disk transparently appear to be a subdirectory of the file system to which it is attached.

• The SENDMAIL:

Post Office Protocol version-3

SMTP

IMAP

References

• http://www.linux.org• http://en.wikipedia.org/selinux• IEEE Papers like:• Analysis and Study of Security

Mechanism Inside Linux Kernel