Detailed method of configuring CentOS devices using Quagga software

Quagga is a routing software that can turn Linux devices into routers and implement powerful real router functions. So what do you do? Let's take a look at how to use Quagga to configure CentOS devices.

Quagga supports several major routing protocols, such as RIP, OSPF, BGP, or ISIS routers. It is fully prepared for IPv4 and IPv6 and also supports routing/prefix filtering. In the unlikely event that a router in your production environment fails and there are no spare routers on hand, and replacements are sent, the Quagga can come in handy. As long as it is properly configured, Quagga can even be configured as a router in a production environment.

In this tutorial we will connect two hypothetical branch networks (such as 192.168.1.0/24 and 172.17.1.0/24) with a dedicated link between the two networks.

Our CentOS equipment at both ends of this dedicated link. The host names of these two devices are set to “site-A-RTR” and “site-B-RTR” respectively. Information about the IP address is provided below.

Site-A: 192.168.1.0/24

Site-B: 172.16.1.0/24

Equivalence between two Linux devices: 10.10.10.0/30

The Quagga package contains several daemons that run in concert. We will focus on setting up the following daemons in this tutorial.

Zebra: The core daemon, responsible for kernel interfaces and static routing.

Ospfd: IPv4 OSPF daemon.

Installing Quagga on CentOS

We first use yum to install Quagga.

# yum install quagga

On CentOS 7, SELinux prevents /usr/sbin/zebra from being written to its configuration directory by default. This SELinux policy interferes with the installation process we are going to describe, so we want to ban this strategy. To do this, turn off SELinux (not recommended), or enable “zebra_write_config” Boolean expressions as shown below. If you use CentOS 6, you can skip this step.

# setsebool -P zebra_write_config 1

If you don't make this change, we will see the following error when trying to save the Zebra configuration from the Quagga command shell.

Can‘t open configuration file /etc/quagga/zebra.conf.OS1Uu5.

(The configuration file /etc/quagga/zebra.conf.OS1Uu5 could not be opened.)

After the Quagga installation is complete, we configure the necessary peer IP addresses and update the OSPF settings. Quagga comes with a command line shell called vtysh. The Quagga commands used in vtysh are similar to those of major router vendors such as Cisco or Juniper.

The first phase: Configuring Zebra

We first create a Zebra configuration file and then launch the Zebra daemon.

# cp /usr/share/doc/quagga-XXXXX/zebra.conf.sample /etc/quagga/zebra.conf

# service zebra start

# chkconfig Zebra on

Starting the vtysh command shell:

# vtysh

First, we configure the log file for Zebra. To do this, enter the following to enter the global configuration mode in vtysh:

site-A-RTR# configure terminal

and specify the log file location, then exit the mode:

site-A-RTR(config)# log file /var/log/quagga/quagga.log

site-A-RTR(config)# exit

Permanently save the configuration:

site-A-RTR# write

Next, we determine the available interfaces when necessary and then configure the IP address.

site-A-RTR# show interface

Interface eth0 is up, line protocol detection is disabled

. . . . .

Interface eth1 is up, line protocol detection is disabled

. . . . .

Configuring eth0 parameters:

site-A-RTR# configure terminal

site-A-RTR(config)# interface eth0

site-A -RTR(config-if)# ip address 10.10.10.1/30

site-A-RTR(config-if)# description to-site-B

site-A-RTR( Config-if)# no shutdown

Continue to configure eth1 parameters:

site-A-RTR(config)# interface eth1

site-A-RTR(config-if )# ip address 192.168.1.1/24

site-A-RTR(config-if)# description to-site-A-LAN

site-A-RTR(config-if) # no shutdown
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