Tag Archives: centos

OSPF routing between Ubuntu and CentOS using Quagga

Topology:

Scenario:

  • Routers: 1 Ubuntu Linux with 2 nics, 1 Centos Linux with 2 nics.
  • Clients: 2 Windows 7 with 1 nic.

IP Details:

All the Routers in this scenario have a default password of “zebra“.

UbuntuRouter:

  • eth0: 192.168.10.1/24
  • eth1: 10.10.10.1/24

CentOSRouter:

  • eth0: 192.168.10.2/24
  • eth1: 172.16.10.1/24

Clients:

  • Dektop: 172.16.10.50/24
  • Laptop: 10.10.10.50/24

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How to install Java 6 on CentOS 6.2

First, we will check that java is already install or not on our system?

java -version

As, we can see that the java is not install on our system, so we will downloads the Java binary installer from Oracle. (In this example, we will download & install the jdk, but the procedure is exactly the same for jre).

Transfer the downloaded file (jdk-6u32***) to the CentOS from Windows machine using WinSCP.

Now, move to the directory where you copy the jdk file(in my case, it is in tmp directory) and give execute permission to jdk file:

cd /tmp/
sudo chmod +x jdk-6u32-linux-x64-rpm.bin

Run the jdk file:

sudo ./jdk-6u32-linux-x64-rpm.bin

Apply the alternatives:

sudo alternatives --install /usr/bin/java java /usr/java/jdk1.6.0_32/bin/java 17000 

We are done 🙂

Check the installed version of java:

java -version

 

Hope this will help you!

 

Please Remember me in your prayers!



InterVLAN Routing using CentOS with 1 Interface

Scenario:
  • Router: CentOS Server with 1 network card.
  • Clients: 2 WindowsXP in VLAN10,1 Ubuntu and 1 CentOS in VLAN20.
  • Switch: Cisco 2960
Cisco 2960 Switch Configuration:
interface FastEthernet0/1
description CONNECTED TO CentOS ROUTER
switchport mode trunk
!
!
!
interface FastEthernet0/5
description WINXP-1
switchport access vlan 10
switchport mode access
!
interface FastEthernet0/6
description WINXP-2
switchport access vlan 10
switchport mode access
!
!
!
interface FastEthernet0/15
description UBUNTU CLIENT
switchport access vlan 20
switchport mode access
!
interface FastEthernet0/16
description CentOS CLIENT
switchport access vlan 20
switchport mode access
CentOS Router Configuration:

First, we need to disable the SELinux:

sudo nano /etc/selinux/config

Change SELINUX from enforcing to disabled:

To configure the base interface(in my case, eth0):

sudo nano /etc/sysconfig/network-scripts/ifcfg-eth0

It should have at least the following elements:

DEVICE=eth0 
BOOTPROTO=none   #if it didn’t work then use static
ONBOOT=yes 
TYPE=Ethernet

To setup a VLAN10, on eth0, then we should create a file ifcfg-vlan10 inside /etc/sysconfig/network-scripts/:

ifcfg-vlan10 should have following elements:

Again to setup a VLAN20, on eth0, then we should create a file ifcfg-vlan20 inside /etc/sysconfig/network-scripts/:

ifcfg-vlan20 should have following elements:

To enable ip forwarding, edit /etc/sysctl.conf file:

sudo nano /etc/sysctl.conf

Change net.ipv4.ip_forward from 0 to 1:

Restart the Networking service:

sudo service network restart

Use the ifconfig command to check the newly created vlan interfaces:

ifconfig

To forward the traffic between the vlans, we should configure the iptables:

sudo nano /etc/sysconfig/iptables

Add these two lines (place them according to your iptables file configuration):

-A FORWARD -i vlan10 -o vlan20 -m state --state NEW,RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -i vlan20 -o vlan10 -m state --state NEW,RELATED,ESTABLISHED -j ACCEPT

Test from WinXP-1:

Test from WinXP-2:

Test from Ubuntu Client:

Test from CentOS Client:

 

Hope this will help you!

 

Please Remember me in your prayers!


How to Setup a DHCP Server on CentOS 6.2

In this scenario, we have a CentOS server with two network cards, but it will only listen the dhcp request on one card (eth1).

Here is the configuration of eth1 interface:

cat /etc/sysconfig/network-scripts/ifcfg-eth1

CentOS as DHCP Server:

To install dhcp server, enter the following command at a terminal prompt:

sudo yum -y install dhcp

To make the dhcp server start at boot time, use this commands:

sudo chkconfig dhcpd on

As we are using more than one network card(s) in our CentOS server, so we need to specify on which interface our server will be listen for dhcp request. (By default, it listens on eth0).

You can change this by editing  /etc/sysconfig/dhcpd file:

sudo nano /etc/sysconfig/dhcpd

Add the name of the interface on which you want that your server will listen for dhcp request (In my case, it is eth1):

DHCPDARGS=eth1

Copy the default configuration file from  /usr/share/doc/dhcp-versidhcp/dhcpd.conf.sample to the /etc/dhcp/dhcpd.conf :

sudo cp /usr/share/doc/dhcp-*/dhcpd.conf.sample /etc/dhcp/dhcpd.conf

Now we will change the default configuration by editing /etc/dhcp/dhcpd.conf, I normally delete everything inside the file and manually add the configuration that suits my needs :-)

sudo nano /etc/dhcp/dhcpd.conf

Here is my dhcpd.conf file, you need to change it according to your needs:

ddns-update-style none;
authoritative;
log-facility local7;
default-lease-time 600;
max-lease-time 7200;
option subnet-mask 255.255.255.0;
option broadcast-address 172.16.10.255;
option routers 172.16.10.1;
option domain-name-servers 172.16.10.1;
option domain-name "centos.local";
subnet 172.16.10.0 netmask 255.255.255.0 {
 range 172.16.10.10 172.16.10.100;
}

Restart dhcp service using the following command:

sudo service dhcpd restart

Configure Windows as DHCP Client:

Just follow these steps, in order to configure your Windows machine as DHCP client (In my case, it’s Windows XP):

To check the IP Address on Windows XP:

To Check the DHCP Leases on CentOS Server:
cat /var/lib/dhcpd/dhcpd.leases

Hope this will help you!

Please Remember me in your prayers!

RIP routing between Ubuntu and CentOS using Quagga

Topology:

Scenario:

  • Routers: 1 Ubuntu Linux with 2 nics, 1 Centos Linux with 2 nics.
  • Clients: 2 Windows 7 with 1 nic.
IP Details

All the Routers in this scenario have a default password of “zebra“.

UbuntuRouter:

  • eth0: 172.16.10.1/24
  • eth1: 10.10.10.1/24

CentOSRouter:

  • eth0: 172.16.10.2/24
  • eth1: 192.168.10.1/24

Clients:

  • Dektop: 192.168.10.50/24
  • Laptop: 10.10.10.50/24
UbuntuRouter Configuration:

Restart the Router!!!

CentOSRouter Configuration:

Restart the Router!!!

Troubleshooting Steps for CentOS:

Verification from Routers 🙂

Test from Clients 🙂

Make a simple test from Laptop.

Make a simple test from Desktop.

Hope this will help you!

Please Remember me in your prayers!

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