centos Archives - Networking HowTos

Installing VMWare Tools on Linux

May 3, 2020 CentOS, Linux, Ubuntu, VMWare

This guide will step you through the steps to install the VMWare tools onto a Linux machine. In some cases, open-vm-tools may already be installed as a default package in your distribution.

Below are some example installation commands.

If you are running a non graphical/server operating system, use the server examples. If you are running a graphical/desktop version, use the desktop examples.

Ubuntu/Debian Server (No GUI)

$ sudo apt install open-vm-tools

Ubuntu/Debian Desktop (GUI)

$ sudo apt install open-vm-tools-desktop

RHEL/Fedora/CentOS Server (No GUI)

$ sudo yum install open-vm-tools

RHEL/Fedora/CentOS Desktop (GUI)

$ sudo yum install open-vm-tools-desktop

adding persistent static routes on centos

June 6, 2017 CentOS, Linux

When you need to access networks located on a different network segment, you need to have a route set up so the PC knows how to get to the other network segment. This generally just points to your main gateway, but you may want to set up additional static routes, where you don’t want the traffic going through your main default gateway.
To set up a static route on CentOS so that it automatically gets created every time the PC starts, you need to create a ‘route-<interface>‘ file in the ‘/etc/sysconfig/network-scripts’ folder.
Use your favorite text editor and edit/create the route-<interface> file.
eg:

# nano /etc/sysconfig/network-scripts/route-eth0

The route will get set up when the specified interfaces comes up.
This file will probably wont exist if you don’t have any existing static routes.
Add a line with the route information in the following format to the file.
x.x.x.x/y via z.z.z.z dev interface
where:
x.x.x.x is the subnet address.
y = the subnet mask. eg. 24
z.z.z.z = the gateway address
interface = the ethernet interface for this route
eg:

192.168.40.0/24 via 192.168.30.1 dev eth0

Modify the above to suit the route you want to add. If you take off the “dev eth0” part it will automatically determine which interface to use at the time.
To make these changes take effect, you can run the following command to bring down the interface, and bring it back up again:
Take down the eth0 interface, and bring it back up:

# ifdown eth0; ifup eth0

or
Restart all network interfaces:

# /etc/init.d/network restart

or simply try a reboot.
Run the following command to ensure the route has been set up correctly:

$ route -n

Get The Active DNS Servers On Linux

June 1, 2017 CentOS, Linux, Networking, Ubuntu

The Domain Name System (DNS for short) is one of the most important parts of the internet infrastructure. It converts the easy to remember domain names, into IP (and IPv6) addresses, that aren’t so friendly to the end user.
Regardless of the distribution of Linux that you are using (such as Ubuntu, CentOS, Debian, Arch, Redhat, etc), the process of determining what DNS servers are currently being used for domain name resolution is the same.
To determine what DNS servers are being used, you simply need to view the contents of the “/etc/resolv.conf” file. This can be done via a graphical editing tool such as gedit, or can easily be viewed from the command line with a simple “cat” of the file, to show the contents. The command below will outline how to determine the DNS servers in use.
Show the active DNS servers on Linux:

$ cat /etc/resolv.conf

You will end up with some output like this:

# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
#     DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
nameserver 8.8.8.8
nameserver 8.8.4.4

You may or may not have the comments at the top of the file, as that will depend on your distribution, but you should have at least one or more “nameserver” records. These will be the name server IP’s that your system will currently be using. In this example, 8.8.8.8 and 8.8.4.4.
Note that this must be an IP address, and cant be a domain name.

Install the dig DNS lookup utility on CentOS

July 23, 2013 CentOS, Linux

The dig DNS lookup utility is a handy tool for performing DNS queries. The dig utility is part of the bind utilities package in CentOS. The following command can be used to install dig.
Install dig (the bind-utils package):

# yum install bind-utils

Note: Make sure you run the above command as a user with root privledges.
You should now be able to use dig to perform DNS lookups. See ‘man dig’ for more information.

List all hard disks connected to a CentOS system

February 1, 2013 CentOS, Linux

You often need to know what physical drives are attached to a system, how many drives are connected, or even what device names match up with which physical drive. There is a handy tool called ‘lshw’ which is used to extract detailed information on the hardware in the PC. Unfortunately this doesn’t come pre-installed on CentOS. The details below will go through installing lshw, and how to run it to list all the hard drives.
Prerequisites
This guide requires the EPEL repository to be configured.
Install the EPEL repostitory:

# yum -y install http://dl.fedoraproject.org/pub/epel/6/i386/epel-release-6-8.noarch.rpm

Install the lshw package:

# yum -y install lshw

List all disks in the system:

# lshw -class disk -short

This will list all disks and storage devices. This includes DVD drives, USB memory sticks, etc.
Example output:

# lshw -class disk -short
H/W path           Device      Class      Description
=====================================================
/0/100/7.1/0.0.0   /dev/cdrom  disk       DVD-RAM writer
/0/100/10/0.0.0    /dev/sda    disk       10GB SCSI Disk
#

Save iptables firewall config on CentOS 6

February 1, 2013 CentOS, Linux

Changes you make to iptables firewall rules only exist for the current boot, and if you don’t save the config, you will loose any changes upon rebooting.
CentOS 6 blocks most incoming ports by default, so you will generally have to make changes to the firewall if you install any new packages. Thankfully CentOS 6 provides the ability to easily save the configuration.
To save the current iptables firewall config, issue the following command:

# service iptables save

Example output:

# service iptables save
iptables: Saving firewall rules to /etc/sysconfig/iptables:[  OK  ]
#

During the next system boot up, or the next time the iptables rules are reloaded, your firewall settings will be reloaded.

Installing NGINX, PHP, and MySQL on CentOS 6

January 23, 2013 CentOS, Linux

This “how to” guide will step you through the process of setting up Nginx, PHP, and MySQL on CentOS 6.
Continue Reading…

Installing HAProxy on CentOS 6

June 25, 2012 CentOS, Linux

This guide will step you through the process of installing HAProxy on CentOS 6.
To install HAProxy on CentOS 6 you first need to set up your installation to use the epel software repository. HAProxy is not available in the default CentOS repositories.
(Note: All commands below require root privileges.)

rpm -Uvh http://download.fedoraproject.org/pub/epel/6/i386/epel-release-6-7.noarch.rpm

You can now install haproxy.

yum -y install haproxy

Now that HAProxy is installed, you can configure the haproxy.cfg file.

vi /etc/haproxy/haproxy.cfg

Once you have configured HAProxy, its time to start the service.

service haproxy start

By default HAProxy wont be set to run at system startup. To enable HAProxy to always start when the PC boots up, run the following:

chkconfig haproxy on

For more information on configuring HAProxy, please check my other howto articles.

Monitoring Compaq or HP Smart Array RAID status on CentOS

June 24, 2012 CentOS, Linux

This howto will step you through the process of setting up the required software to be able to check the status of a Compaq or HP Smart Array and the attached physical and logical drives on CentOS 6 or RHEL.
The required program to be able to talk to the Smart Array is called ‘hpacucli’, which can be found in the ‘HP Service Pack for ProLiant’ package.
(Note: Some of the commands below require root privileges.)
Obtaining and Installing the ‘hpacucli’ utility
You have two options here. Downloading the full HP service pack package and extracting the required RPM, or downloading the single required RPM.
Download Option 1: Download the full ‘HP Service Pack for ProLiant’ package.

wget "ftp://ftp.hp.com/pub/softlib2/software1/cd-generic/p1959651341/v78385/SPPMDSLRH-2012.06.0B-0.zip"

Unzip the downloaded package:

[root@localhost ~]# unzip SPPMDSLRH-2012.06.0B-0.zip
Archive:  SPPMDSLRH-2012.06.0B-0.zip
  inflating: SPPMDSLRH2012060B.2012_0525.1.iso
  inflating: SPPMDSLRH2012060B.2012_0525.1.iso.md5sum
  inflating: README.txt

Create a temporary folder and mount the ISO image so we can access the required package:

[root@localhost ~]# cd ~
[root@localhost ~]# mkdir cdimage
[root@localhost ~]# mount SPPMDSLRH2012060B.2012_0525.1.iso -o loop,ro cdimage
[root@localhost ~]# cd cdimage
[root@localhost cdimage]# cd hp/swpackages
[root@localhost swpackages]#

Download Option 2: Downloading the individual RPM file.

wget ftp://ftp.hp.com/pub/softlib2/software1/pubsw-linux/p1257348637/v71527/hpacucli-9.10-22.0.x86_64.rpm

(Please see the comment from “fvanler” at the bottom of this article for a link to the HP site for the above RPM.)
Install the hpacucli RPM package:

yum install hpacucli-9.10-22.0.x86_64.rpm

Note: If you used download option 1, make sure you are in the cdimage/hp/swpackages folder before running the above command.
Output:

[root@localhost swpackages]# yum install hpacucli-9.10-22.0.x86_64.rpm
Loaded plugins: fastestmirror, presto
Loading mirror speeds from cached hostfile
 * base: mirror.internode.on.net
 * extras: mirror.internode.on.net
 * updates: mirror.internode.on.net
Setting up Install Process
Examining hpacucli-9.10-22.0.x86_64.rpm: hpacucli-9.10-22.0.x86_64
Marking hpacucli-9.10-22.0.x86_64.rpm to be installed
Resolving Dependencies
--> Running transaction check
---> Package hpacucli.x86_64 0:9.10-22.0 will be installed
--> Finished Dependency Resolution
Dependencies Resolved
============================================================================================
 Package          Arch           Version           Repository                          Size
============================================================================================
Installing:
 hpacucli         x86_64         9.10-22.0         /hpacucli-9.10-22.0.x86_64          17 M
Transaction Summary
============================================================================================
Install       1 Package(s)
Total size: 17 M
Installed size: 17 M
Is this ok [y/N]: y
Downloading Packages:
Running rpm_check_debug
Running Transaction Test
Transaction Test Succeeded
Running Transaction
  Installing : hpacucli-9.10-22.0.x86_64                                                1/1
DOWNGRADE NOTE: To downgrade this application to any version prior to 9.10.x.x, the current
RPM must be manually uninstalled using the "rpm -e" command before any prior versions can be
installed.
LOCKING NOTE: The locking mechanism starting with versions 9.10.X.X, are not compatible with
prior versions of the applications. Therefore, mixing older and newer versions of the various
applications (ACU, HPACUCLI, HPACUSCRIPTING) is not recommended.
Installed:
  hpacucli.x86_64 0:9.10-22.0
Complete!

Unmount the ISO image, as it is no longer required:
(This is only required if you used the full HP package.)

[root@localhost swpackages]# cd ~
[root@localhost ~]# umount cdimage

The installation is now complete, and you are ready to check the status of your Smart Array.
Check the controller status

hpacucli controller all show status

Sample Output:

Smart Array 6i in Slot 0 (Embedded)
   Controller Status: OK
   Cache Status: Temporarily Disabled
   Battery/Capacitor Status: Failed (Replace Batteries/Capacitors)

Keep note of the slot number, as this will be used when checking the logical and physical drives.
Check the logical drive

hpacucli controller slot=0 logicaldrive all show status

Sample Output:

   logicaldrive 1 (67.8 GB, RAID 5): OK

Check the physical drives

hpacucli controller slot=0 physicaldrive all show status

Sample Output:

   physicaldrive 2:0 (port 2:id 0, 36.4 GB): OK
   physicaldrive 2:1 (port 2:id 1, 36.4 GB): OK
   physicaldrive 2:2 (port 2:id 2, 36.4 GB): OK
   physicaldrive 2:3 (port 2:id 3, 36.4 GB, spare): OK

Setting up periodic monitoring
Now that the ‘hpacucli’ tool is installed, you can configure a monitoring tool such as Nagios to periodically check the status of your array/drives.
To do this with Nagios, you will need to use the ‘check_hparray’ plugin.
This can be downloaded from the following site:
http://exchange.nagios.org/directory/Plugins/Hardware/Server-Hardware/HP-(Compaq)/check_hparray/details.

Installing lspci on CentOS

June 23, 2012 CentOS, Linux

The lspci command, which can be found in the pciutils package, is a great tool for finding information on the devices in your PC. the lspci command will allow you to get the model number/chip details for devices such as network interface cards, sound cards, raid cards, etc.
To install pciutils on CentOS/RHEL using yum:
(make sure you are logged in with root privileges)

# yum install pciutils

Example installation output:

# yum install pciutils
Loaded plugins: fastestmirror, presto
Loading mirror speeds from cached hostfile
 * base: mirror.internode.on.net
 * extras: mirror.internode.on.net
 * updates: mirror.internode.on.net
Setting up Install Process
Resolving Dependencies
--> Running transaction check
---> Package pciutils.x86_64 0:3.1.4-11.el6 will be installed
--> Finished Dependency Resolution
Dependencies Resolved
======================================================================================
 Package             Arch              Version                  Repository       Size
======================================================================================
Installing:
 pciutils            x86_64            3.1.4-11.el6             base             83 k
Transaction Summary
======================================================================================
Install       1 Package(s)
Total download size: 83 k
Installed size: 177 k
Is this ok [y/N]: y
Downloading Packages:
Setting up and reading Presto delta metadata
Processing delta metadata
Package(s) data still to download: 83 k
pciutils-3.1.4-11.el6.x86_64.rpm                               |  83 kB     00:00
Running rpm_check_debug
Running Transaction Test
Transaction Test Succeeded
Running Transaction
  Installing : pciutils-3.1.4-11.el6.x86_64                                       1/1
Installed:
  pciutils.x86_64 0:3.1.4-11.el6
Complete!
#

Running lspci:

# lspci

Output example:

# lspci
00:00.0 Host bridge: Intel Corporation 440BX/ZX/DX - 82443BX/ZX/DX Host bridge (rev 01)
00:01.0 PCI bridge: Intel Corporation 440BX/ZX/DX - 82443BX/ZX/DX AGP bridge (rev 01)
00:07.0 ISA bridge: Intel Corporation 82371AB/EB/MB PIIX4 ISA (rev 08)
00:07.1 IDE interface: Intel Corporation 82371AB/EB/MB PIIX4 IDE (rev 01)
00:07.3 Bridge: Intel Corporation 82371AB/EB/MB PIIX4 ACPI (rev 08)
00:07.7 System peripheral: VMware Virtual Machine Communication Interface (rev 10)
00:0f.0 VGA compatible controller: VMware SVGA II Adapter
00:10.0 SCSI storage controller: LSI Logic / Symbios Logic 53c1030 PCI-X Fusion-MPT Dual Ultra320 SCSI (rev 01)
00:11.0 PCI bridge: VMware PCI bridge (rev 02)
00:15.0 PCI bridge: VMware PCI Express Root Port (rev 01)
00:18.5 PCI bridge: VMware PCI Express Root Port (rev 01)
00:18.6 PCI bridge: VMware PCI Express Root Port (rev 01)
00:18.7 PCI bridge: VMware PCI Express Root Port (rev 01)
02:00.0 Ethernet controller: Advanced Micro Devices [AMD] 79c970 [PCnet32 LANCE] (rev 10)
#

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