Linux Administration

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Basic about Linux• What is Linux ?

-Linux is an open source, freely distributable Unix like operating system that uses Linux kernel .

• What is Kernel ?

- Kernel is the program acting

as chief of operations.

• Is Linux Free?

-Yes, Linux is one of the most prominent examples of free and open source software collaboration.

Installation of LinuxMethods of installing Linux:

-FTP:-This is one of the earliest methods for performing network installations.

-HTTP:-The installation tree is served from a web server.

-NFS:-The distribution tree is shared/exported on an NFS server.

-SMB:- This method is relatively new, and not all distributions support it. The installation tree can be shared on a Samba server or shared from a Windows box.

-From the Optical Media

• Username Field :

• Password Field :

• User-ID Field (UID):

• Group-ID Field (GID):

• GECOS:

• Directory:

• Shell:

Managing User Account

• Under Linux, every file and program must be owned by a user. Each user has a unique identifier called a user ID (UID).

• Each user must also belong to at least one group, a collection of users established by the system administrator.

• Users may belong to multiple groups. Like users, groups also have unique identifiers, called group IDs (GIDs).

• The /etc/passwd file stores the user’s login, encrypted password entry, UID, default GID, name (sometimes called GECOS), home directory, and login shell.

Managing User Account

A file system is a data structure which interprets the physical sector of a disc into logical

directory structure. The logical structure will help computers and users +to trace files. The file

system registers the location of the files and directories on the disc .

File System of Linux

Network Configuration The ifconfig program is primarily responsible for setting up

network interface cards (NICs).

All of its operations can only be performed through command-line options, as its native format has no menus or graphical interface.

Multiple IP address can be assigned for single NIC.

Network configuration file stores in /etc/sysconfig/network-scripts/ifcfg

Global Parameter configuration file stores in /etc/sysconfig/network.

Network Configuration File• DEVICE=eth1

• BOOTPROTO=none

• HWADDR=00:12:79:9E:DC:0B

• ONBOOT=yes

• TYPE=Ethernet

• DHCP_HOSTNAME=rcciit.com

• USERCTL=no

• PEERDNS=yes

• IPV6INIT=no

• IPADDR=192.168.250.24

• NETMASK=255.255.255.0

• GATEWAY=192.168.250.21

DHCP

• DHCP provides a method for hosts on a network to request, and be granted, configuration information including the addresses of router and nameservers.

• DHCP forwarding agents allow clients to receive addresses from a server which is not located on the same network segment.

• IP addresses are either dynamically assigned from a range or pool of addresses or statically assigned by MAC address.

Service Profile: DHCP• Packages: dhcp

• Daemons: dhcpd

• Script: dhcpd

• Ports: 67(bootps), 68(bootpc)

• Configuration: /etc/dhcpd.conf

/var/lib/dhcp/dhcpd.leases

• Related: dhclient

• Sample configuration provided under : /usr/share/doc/dhcp - <version>

FTP

• FTP configuration file stores in /etc/vsftpd/vsftpd.conf

• Default User(Anonymous) can access only /var/ftpG

• Generally used to transfer single with proper authentication from previously configured sender’s folder to reciver’s folder

FTP Configuration File

• anonymous_enable=YES

• anon_upload_enable=YES

• /etc/vsftpd/ftpusers ==> denied access

• /etc/vsftpd/user_list ==> userlist_enable=YES

• userlist_deny=YES/NO

Telnet• Telnet is a network protocol used on the Internet or local area

networks to provide a bidirectional interactive text-oriented communications facility using a virtual terminal connection. User data is interspersed in-band with Telnet control information in an 8-bit byte oriented data connection over the Transmission Control Protocol (TCP).

• Telnet can not restrict a user after connection to the host has made, (i.e a user telnetting to a remote host can totally access the host computer if he logged in as a root)

Network File System/Service

• The Network File System (NFS) was developed to allow machines to mount a disk partition on a remote machine as if it were a local disk. It allows for fast, seamless sharing of files across a network.

• Exported directories are defined in /etc/exports

• Each entry specifies the hosts to which the filesystem is exported plus associated permission and options

THANK YOU !!

Linux Administration Basic about Linux Installation of Linux Network Configuration Network Configuration File DHCP Service Profile: DHCP FTP FTP Configuration File Telnet Network File System/Service THANK YOU !!