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271 - Status Check for network NIC bonding

Bonding is nothing but Linux kernel feature that allows to aggregate multiple like interfaces (such as eth0, eth1) into a single virtual link such as bond0.
The idea is pretty simple get higher data rates and as well as link failover. Sometimes you need to monitor the status on its health.

1. Check MAC Address & General information

269 - Setup default gateway

To setup default gateway :

1. Modifying the /etc/sysconfig/network.

# vi /etc/sysconfig/network

* Setup GATEWAY={Router-IP}




2. Save and close the file.

268 - Configuring TCP KeepAlive Parameters

Linux server uses the settings for the TCP KeepAlive parameter to clean up connections from clients that have disconnected
without releasing a license that has been checked out.

You can change the TCP KeepAlive parameter if you need the abandoned license checkouts to be cleaned up more frequently.

The KeepAlive parameter names vary by operating system but generally specify :

263 - Multipath

To be able to support failover connections to a device one needs multiple paths to that device.
If we have a iSCSI disk connected to an ethernet network and we want to make sure that we can reach the disk from a host
even when we disconnect one ethernet cable we need two network cables running from the host to the disk and we need a piece of software
that makes sure when one link failes the other one is used.  This last piece of software is called multipath on GNU/Linux systems.

1. Setup Multipath package

262 - ext4

To use ext4 file system, you need to have RedHat v5.3 or later, It means boot into 2.6.18-128.el5 or higher, and need a package.

# yum install e4fsprogs

The e4fsprogs package is designed to install alongside stock e2fsprogs without overlapping, so some utilities are renamed;
for example e4fsck, debuge4fs, e4image,   etc. rpm -q e4fsprogs | grep bin will give a good summary of what is included.

260 - awstats Installation

1. Installation

# wget http://prdownloads.sourceforge.net/awstats/awstats-7.0-1.noarch.rpm

# # rpm -ihv awstats-7.0-1.noarch.rpm

Awstats has been installed in /usr/local/awstats .

2. Apache configuration

258 - Change IP Address on VMWare ESXi

1. Check the NIC information

# ifconfig

# ifconfig vswif0

2. Change IP Address for a NIC

257 - nagios CHECK_NRPE: Socket timeout after 10 seconds

You may get the following error (Service Check Timed Out) in the Service Status Details part of Nagios for all your NRPE service checks.
You can extend the timeout as the following.

1. nagios command change

If you want to increase it to 60 seconds :

# vi /usr/local/nagios/etc/objects/commands.cfg


256 - Linux Single Mode

On an x86 system using GRUB, use the following steps to boot into single-user mode:

1. At the GRUB splash screen at boot time, press any key to enter the GRUB interactive menu.

2. Select Red Hat Enterprise Linux with the version of the kernel that you wish to boot and type a to append the line.

3. Go to the end of the line and type "single" as a separate word
   (Press the Spacebar and then type "single").  Press Enter to exit edit mode and save the change.

254 - CUPS shared printer configuration

All you need to make this work are a central Linux/CUPS printer server, and one Linux PC per subnet to act as a relay printer server.

You have two subnets, and You need to have routing already configured to pass traffic between the two subnets,
so everyone can ping everyone. So you have your CUPS printer server at, and you want computers on to be able to use it.
This is a complete, barebones example CUPS configuration for

1. Print Server ( configuration


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by Dr. Radut