tag:blogger.com,1999:blog-88450789613796034632026-01-04T10:32:10.185+05:30UNIX, Linux Concepts, Commands, Advance Linux, Linux Networking and Servers, Shell Scripting.Vedhttp://www.blogger.com/profile/12521066212539267018noreply@blogger.comBlogger63125tag:blogger.com,1999:blog-8845078961379603463.post-87659571993034940782014-11-19T20:23:00.000+05:302014-11-19T20:44:53.724+05:30

Apache Web Server: Introduction and Installation What is Apache web Server? Apache is a most popular, freely available open source web server. A Web server accepts HTTP requests from web clients and serves them HTTP responses in the form of web pages that contains static (text, images etc) and dynamic (scripts) content.According to the Apache Software Foundation:The name 'Apache' was chosen

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Options to restrict the security in Samba Server valid users It is required when some users only can access the directory, not all users. [sales] path = /home/samba/salescomment = Sales Datawriteable = yesvalid users = tom dick harry Here sales directory can be accessed by the user listed in valid users. invalid users To explicitly deny the listed users access we use invalid users.

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Samba User authentication and security If we want only valid user can only access the Samba server then we use security as user in global section. If we set security = user in global section then user will require to provide password to access the Samba Server. The global for user security [global]workgroup = WORKGROUPserver string = Samba Servernetbios name = LinuxSambasecurity = user

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Samba User Creation on Samba Server We can create a user for Samba Server who can own files and directories. First we create a Linux user who can’t login to any shell. # useradd -s /bin/false sambauser# passwd passwordChanging password for user sambauser.New UNIX password:Retype new UNIX password:passwd: all authentication tokens updated successfully. Now we create a samba share

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Echo Command Echo is a shell built-in command used to display a line of text on standard output.echo with -e option enables interpretation of backslash escapesSome backslashes used for different purpose are: \\ backslash \a alert (BEL) \b backspace \c suppress trailing newline \f form feed \n new line \r carriage

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Sharing Files and Directories with Samba Update the global section of configuration file smb.conf as below[global]workgroup = WORKGROUPserver string = Samba Servernetbios name = LinuxSambasecurity = shareEnter the name of workgroup, put server string name as you wish, write the netbios name and security as share. Security option Security has many options as share, user, domain, ads and

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Date Command Date command is used to display the current date and time or setting the system date and time on terminal or through ssh session. date command Examples To display the current date and time use date command $ dateThu Aug 28 17:50:29 IST 2014 To Display The Hardware Clock (RTC), you need to be root user to use hwclock command. #hwclockThu 28 Aug 2014 05:56:45 PM IST

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bc Command in Linux with Example bc is a command line basic calculator. bc is typically used as either a mathematical scripting language or as an interactive mathematical shell.Doing arithmetic calculation use bc as below. bc can be used with echo command Addition $ echo "3+5" | bc8 Substraction $ echo "15-3" | bc12 Multiplication $ echo "2*8" | bc16 Division $ echo "2/3" | bc0$ echo "6/4" |

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Configuring Samba Server To install Samba run command yum install samba samba-client samba-common The Samba Configuration file is /etc/samba/smb.conf Take a backup of this file before configuring any samba share using command mv /etc/samba/smb.conf /etc/samba/smb.conf.bkp Minimal smb.conf Here is an example of a minimum configuration of smb.conf $ cat /etc/samba/

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Linux Basic Command - cal to display calendar Cal displays a simple calendar.  If arguments are not specified, the current month is displayed.  The options are as follows:      -1      Display single month output.  (This is the default.)      -3      Display prev/current/next month

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Samba daemons Samba consists mainly three daemons nmbd, smbd and winbindd and one management service application SWAT. nmbd The nmbd daemon takes care of all the names and naming. This daemon listens for name-server requests and provides the appropriate IP addresses when called upon. It registers and resolves names, and handles browsing. According to the Samba documentation, it should be

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What is Samba? Samba is an Open Source and Free Software suite that provides seamless file and print services to SMB/CIFS clients." Samba is freely available and used to communicate with Linux/Unix servers and Windows-based clients.Samba implements the CIFS network protocol. Samba offers many services. It can share one or more directory tree. It also provides Windows Internet Name Service (

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Installing NFS Server and NFS Client We need to install NFS packages (nfs-utils and nfs-utils-lib ) which contains all required NFS services  on our NFS Server as well as on NFS Client machine. We can install it via “yum” (Red Hat Linux) and “apt-get” (Debian and Ubuntu) package installers.[root@nfsserver ~]# yum install nfs-utils nfs-utils-lib[root@nfsserver ~]# yum install portmap (not

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NFS Services All NFS versions rely on Remote Procedure Calls (RPC) between clients and servers. RPC services under Red Hat Enterprise Linux 6 are controlled by the rpcbind service. To share or mount NFS file systems, the following services work together. rpcbind (portmap in older versions of Linux) The primary daemon upon which all the others rely, rpcbind manages connections for

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Configuration Files of NFS Server in Linux Main configuration files to set up an NFS server is /etc/exports.Other two file required to restrict IP address are /etc/hosts.allow, and /etc/hosts.deny. /etc/exports This file contains a list of directory that is shared and its options. An entry in /etc/exports is like /nfsdir 192.168.1.101(rw,sync,no_root_squash) 192.168.1.102(ro,sync)

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NFS (Network File System) NFS stands for Network File System, a file system developed by Sun Microsystems, Inc. A Network File System (NFS) allows remote hosts to mount file systems over a network and interact with those file systems as though they are mounted locally. For example, if you were using a computer linked to a second computer via NFS, you could access files on the second computer

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When Linux booting process is completed it display the login prompt. There are different process running in Linux when any user login to their shell. these processes are as follows. Login process steps Init starts getty process getty process initiates login prompt on terminal login command check user credentials from /etc/passwd getty starts user shell process shell reads

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Telnet Telnet protocol allows you to connect to remote hosts over TCP/IP network (such as the Internet). Using telnet client software on your computer, you can make a connection to a telnet server (i.e., the remote host). Once your telnet client establishes a connection to the remote host, your client becomes a virtual terminal, allowing you to communicate with the remote host from your

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Linux Commands of FTP Server Command to connect ftp server ftp ftp.example.comftp 192.268.10.20ftp user@ftp.example.comThis command will attempt to connect to the ftp server. If it succeeds, it will ask to log in using a username and password. Public ftp servers often allow you to log in using the username "anonymous". FTP Prompt When you enter your loginname and password for the ftp

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Configuration of VSFTPD Vsftpd configuration file can be found on /etc/vsftpd/vsftpd.conf. After making any change in the file you need to restart the vsftpd service.Default settingBy default ftp is set for anonymous login, and only permits download not upload.Anonymous user cannot create directory in default setting.By default VSFTPD uses directory /var/ftpDefault log file location is /var/log

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What is VSFTPD? FTP by itself is not a very secure. Data transmitted in clear text, without encryption so making it subject to interception and theft. Now we have more secure options the Very Secure FTP daemon (vsftpd).  VSFTPD features Virtual IP configurations Powerful per-user configurability Band Width limits Per-source-IP configurability Per-source-IP limits IPv6 compatible

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What is FTP FTP stands for File Transfer Protocol and it is used as one of the most common means of copying files between server and client over a TCP based network like Internet. FTP is the most used protocol over internet to transfer files. Any Linux system can operate as an FTP server. It has to run only the server software—an FTP daemon with the appropriate configuration. Transfers are

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Internal Command Internal commands are the commands that are executed directly by the shell. These commands will not have a separate process. You can’t find these commands in PATH directories in system because these are built in shell command. echo is an external command and if you try to find its path it will show shell built in. $ type echo echo is a shell builtin when you run echo

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Name Resolver The name resolver is used to convert a human friendly name (hostname) to machine friendly name i.e. (IP address). It is use to configure client side access to the Internet Domain Name System (DNS). This file defines which name servers to use. Fully Qualified Domain Name A fully qualified domain name (FQDN) is the complete domain name for a specific computer or

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ifconfig command The “ifconfig” or interface configuration command is used for displaying and configuring the network configuration information like ip address, broadcast address, netmask etc. ifconfig is used to configure the system's 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

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