Wednesday, December 29, 2010

Network Services -- Install the packages needed to provide the service

Installing and configuring packages are a base function of managing a Linux environment. Packages are preconfigured files that are design to install an run on multiple systems. The alternative to this is to download the source code for the packages and build them yourself - a step that would stop most people from ever using Linux.
There are 2 basic methods to install packages in redhat: manual installation via RPM, and using a package manager such as YUM.
RPM
RPM is a very versatile and flexible tool that allows for installation, removal, querying and updating of packages on a given system. The only drawback to this tool is that it doesn't handle package dependencies well.
Imagine you are installing program A, and program A requires program B in order to run, using RPM to install program A will fail and report back that you need to install program B first. The administrator must then track down program B and use RPM to install it first, assuming that B doesn't have additional depenencies.

YUM
YUM is a package management tool that allows for multiple distributed repositories of information that can be searched and installed. The tool performs automatic dependency management and will prompt to install any required packages as needed.
YUM is configured with files in the /etc/yum.repos.d/ folder. Each repository needs a minimum of 3 lines, an example is shown below
[RHEL6Server]
name=RHEL6Server
baseurl=http://ftp.redhat.com/pub/redhat/linux/enterprise/6Server/en/os/SRPMS/
For this exam objective, I am going to assume we are installing packages via YUM, and that the below services will be installed. In case you dont know the name of the package to install, try searching for it like yum search ftp
  • HTTP
    • yum install httpd
  • DNS
    • yum install bind bind-utils 
    • NOTE: bind-utils is included to assist in setup and testing
  • FTP
    • yum install ftp vsftpd 
    • NOTE: ftp is included to assist in setup and testing
  • NFS
    • yum install nfs-utils rpcbind 
    • NOTE: rpcbind is needed to enable NFSv3 connections
  • SMB
    •  yum install samba-client samba-common samba
  • SMTP
    • yum install postfix
    • NOTE: alternative SMTP servers can be configured, but this is the default redhat selection
  • SSH
    • yum install openssh-server
  • NTP
    •  yum install ntp ntpdate

No comments: