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PSSH : Parallel SSH to execute commands on a number of hosts

About PSSH
If we are managing a large number of servers , there are times when we need to execute the same command on all the servers. Sometimes need to copy a file to multiple hosts.  For these tasks we can login to each of the servers and execute the command or write a script to automatize the task. Logging  to each of the servers and executing a  command will take a long time and writing a script to automize the task will need a initial effort. In such cases , tools like pssh , pconsole , Clusterssh comes handy. In this post , we will see how to use pssh.

The pssh manual page says "pssh  is  a  program  for executing ssh in parallel on a number of hosts.  It provides features such as sending input to all of the processes, passing a password to ssh, saving output to files, and timing out.


Installing PSSH

Pssh is written using python. The installation steps are somewhat different from the traditional method of using the make the 'make' tool to compile a program and then i…

Configuring Nagios to monitor services using NRPE

In my first blog on nagios configuration Configuring Nagios to monitor localhost ,we had seen how to configure nagios to monitor services on localhost. Now,we will see further how to configure nagios to monitor services on remote host.


Active and Passive Checks
Nagios provides few addons to monitor services on remote hosts. Some of the popular add-ons are 1) NCSA and 2)NRPE
Also it provides two types of checks to monitor services on a remote host.  Active Check and Passive Check: Let's see what are active and passive checks with respect to Nagios.

Active Checks:  Active checks are the most common method for monitoring hosts and services.It is initiated by the monitoring server or in other words the Nagios server. When Nagios needs to check the status of a host or service it will execute a plugin and pass the information about what needs to be checked. The plugin will then check the operational state of the host or service and report the results back to the Nagios daemon. Nagios will…