NETWORKING 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 14 th  Second Linux Version 1.0 released on March 14 th  Third Linux Version 2.0 released on June 1996.

 Fourth Linux Version 2.2 released on Jan  Fifth Linux Version 2.4 released in January  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 Tools PING: ping PING ( ) 56(84) bytes of data. 64 bytes from im-in-f104.google.com ( ): icmp_seq=1 ttl=247 time=98.4 ms 64 bytes from im-in-f104.google.com ( ): icmp_seq=2 ttl=247 time=84.7 ms ping statistics packets transmitted, 2 received, 33% packet loss, time 1998ms rtt min/avg/max/mdev = /91.601/98.434/6.839 ms

NETSTAT : netstat -r Kernel IP routing table Destination Gateway Genmask Flags MSS Window irtt Iface * U eth0 link-local * U 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: nslookup Server: Address: #53 Non-authoritative answer: canonical name = Name: Address:

 TRACEROUTE: traceroute traceroute to ( ), 30 hops max, 40 byte packets

 NMAP: nmap -A Starting Nmap 4.53 ( ) at :01 IST SCRIPT ENGINE: rpcinfo.nse is not a file. SCRIPT ENGINE: Aborting script scan. Interesting ports on ( ):

Internet Services Telnet: telnet Connected to Escape character is '^]'. CentOS release 4.4 (Final) ‏ Kernel ELsmp on an i686 login:

Secure Shell (SSH): ssh The authenticity of host ' ( )' 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 ' (RSA) to the list of known hosts. password:

File Transfer Protocol (FTP): ftp ftp.kernel.org Connected to pub.us.kernel.org. 220 Welcome to ftp.kernel.org. Name (ftp.kernel.org:saurabh): anonymous 331 Please specify the password. Password:

Secure Copy (SCP): The syntax for scp is: scp

Secure File Transfer Program (SFTP): The syntax for sftp is: sftp file

FINGER: 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 IEEE Papers like: Analysis and Study of Security Mechanism Inside Linux Kernel