enabling ip forwarding - installation and configuration of Quagga - configuring OSPF
Materials covered in this lab include:
enabling ip forwarding
installation and configuration of Quagga
configuring OSPF between our three (or more) systems
IP forwarding needs to be enabled in the Linux kernel before the system will forward between interfaces.
This is done via a kernel sysctl value.
To enable forwarding from the command line type:
sysctl -w net.ipv4.ip_forward=1
To enable forwarding for ipv6 from the command line type:
sysctl -w net.ipv6.conf.all.forwarding=1
To insure that these values survive a reboot it is necessary to edit /etc/sysctl.conf where you uncomment
#net.ipv4.ip_forward=1
and
#net.ipv6.conf.all.forwarding=1
Once this is done, it is now possible to create a subnet and assign an ip address to a second interface and then forward a packet arriving on one interface to a destination located on another.
Installing Quagga
Quagga is the routing software suite that we're going to use to support dynamic routing.
We can install it on ubuntu by typing:
$ sudo apt-get install quagga
once installed:
cd /etc/quagga
We need to edit the daemons file, we are going to enable the zebra and ospfd daemons
edit /etc/quagga/daemons and change:
zebra=no
ospfd=no
to yes
before either of the daemons will start configuration files need to be copied into place.
$ sudo cp /usr/share/doc/quagga/examples/zebra.conf.sample /etc/quagga/zebra.conf
$ sudo cp /usr/share/doc/quagga/examples/ospfd.conf.sample /etc/quagga/ospfd.conf
and have their permissions changed:
$ sudo chown quagga.quaggavty /etc/quagga/*.conf
$ sudo chmod 640 /etc/quagga/*.conf
now you can start the routing daemons by typing:
/etc/init.d quagga start
verify that they have started by typing:
ps -fu quagga
The quagga daemons have a cisco style cli, each one listens on it's own port, by default they only listen on localhost. You can telnet to them by typing:
telnet localhost 2601 (for zebra)
telnet localhost 2604 (for ospfd)
log in with the default password (zebra)
lets configure vtysh so that we don't have to use telnet to each individual daemon.
Copy the vtysh config file into place:
cp /usr/share/doc/quagga/examples/vtysh.conf.sample /etc/quagga/vtysh.conf
Edit
/etc/quagga/vtysh.conf
set the hostname entry to:
hostname localhost
then save the file and fix the permissions again:
chown quagga.quaggavty /etc/quagga/*.conf
chmod 640 /etc/quagga/*.conf
then restart quagga
/etc/init.d/quagga restart
set the vtysh pager to something reasonable otherwise actually using it is rather ugly.
$ sudo echo VTYSH_PAGER=more >> /etc/environement
rather than reread the environment we can simply do the following to make this shell work better.
$ export VTYSH_PAGER=more
Interacting with the router
now type:
$ sudo vtysh
once you're at the prompt, you're talking to the combined zebra and ospf routing processes.
# show running-config
the cli from now on is cisco style.
For the sake of generating a combined configuration file type:
# write
Now there is a Quagga.conf configuration file that accurately reflects the contents of both preexisting configuration files...
# exit
you can now remove /etc/quagga/zebra.conf and /etc/quagga/ospfd.conf and restart quagga and the daemons will use the new config.
Configuration
for those of you that know Cisco routers this will seem fairly familiar.
from the command line
$ sudo vtysh
# configure terminal
# router-id 10.X.254.Y
where the X is the group and Y is the pc number
configure interface eth0:1
# interface eth0:1
# ip address 10.x.0.y/26
# description backbone
# ipv6 nd suppress-ra
# exit
configure interface eth0:2
# interface eth0:2
# description host subnet N
replace N with your PC number
# ip address 10.x.y.1/24
# ipv6 nd suppress-ra
# exit
back up one more level
# exit
# show running-config
then write the configuration
# write
Configure OSPF
# conf t
# router ospf
# network 10.X.0.0/16 area 0.0.0.0
# exit
Add a password for the ospf process on the network interface where we're going to be using it.
# interface eth0:1
# ospf authentication-key groupX
where X is the group number.
Back out and write the configuration
# exit
# exit
# write
Now, we are going to configure a static route for an attached subnet, and redistribute that route into ospf
# conf t
# ip route 10.X.Y.0/24 eth0:2
# router ospf
# redistribute static
# exit
# exit
# write
Checking the status of your ospf process
localhost# show ip route
localhost# show ip ospf neighbor
Done with ospf exercise, you should now be able to ping any of the router interfaces within your group.
