Lynuxstuff.com | linux tutorials and Tips

lynuxstuff.com

Tips & Tricks

Most popular

Welcome to lynuxstuff.com

How to synchronize data between two servers using rsync

Rsync: rsync is an application used in unix systems which synchronize files and directories between two machines.rsync behaves like rcp(remote file copy),but it much faster than rcp.because rsync sends the differences in the files instead of sending entire files.

Servers are SERVER_SOURCE & SERVER_DESTINATION

Configure SSH key authentication

In SERVER_DESTINATION open sshd_config file
       vi /etc/ssh/sshd_config
Then verify the following entries

      RSAAuthentication yes
      PubkeyAuthentication yes
      AuthorizedKeysFile .ssh/authorized_keys

save & exit

Then restart ssh daemon

/etc/init.d/sshd restart
Then in SERVER_SOURCE, create a key pair for key authentication between two servers for ssh connection
ssh-keygen -t rsa -b 4096

Monitoring windows Machine using Nagios

By using nagios we can monitor privite services & attributes like

Memory usage
CPU load
Disk usage
Service stats
Running processes etc

Monitoring privite services or attributes of a windows machine requires an agent on it.This agent act as a proxy between the nagios plugin that does the
monitoring and the actual service or attribute of windows machine.Without installing an agent on the windows box,nagios unable to monitor privite services
or attributes.
We are using NSClient++ addon on the windows machine as agent and check_nt plugin communicate with the NSClient++ addon.

Cacti Network graphing Tool -Installation

Cacti is a network graphing tool similar to MRTG.It is a complete front end to RRDtool,it stores all of the necessary information to create graphs and populate them with data in MySql database.The front end is completely PHP driven.

Requirements cacti

MySql server
NET-SNMP server (SNMP is used for network management)
PHP with net-snmp module
Web server

Before going to cacti installation,the required software should be installed and configured
Configuring MySql server
Set root password
   mysqladmin -u root password NEWPASS
create 'cacti' MySql database
   mysql -u root -p -e 'create database cacti'
Create 'cacti' user with some pass
   mysql -u root -p
    mysql> GRANT ALL ON cacti* TO cacti@localhost IDENTIFIED BY 'SOMEPASS';
   mysql> FLUSH privileges;

Nagios upgradation from Previous Nagios 3.x release

Before upgrading you should have a good backup of existing nagios installation and configuration files.If anything goes wrong,then this will allow you to rollback to your old version.
Nagios upgrading don't even need root access.We can do this as 'nagios' user.

Become nagios user by su or sudo command
su -l nagios

Remove the following old html files that were used by web frontend.The have been replaced by PHP equivalents
rm /usr/local/nagios/share/{main,side,index}.html

sysctl

sysctl is an interface that allows you to make changes to a running linux kernel.With /etc/sysctl.conf,you can configure various linux networking and system setting such as