Running your router(s)

Now you have a base olive image. Qemu allows you to use this as a base for other images and only writing the changes to your “slave” images saving on disk space! You can also use less memory for each Qemu instance.

Create a new image off of your base image. Repeat for all your routers you want to emulate:

qemu-img create -b olive-base.img -f qcow2 R1.img

Start your router and then telnet to it:

qemu R1.img -m 96 -nographic -daemonize -serial telnet::2001,server,nowait \
-localtime -net nic,macaddr=00:aa:00:60:01:01,model=e1000 -net user
telnet localhost 2001

Once logged in, you can type “cli” to launch the JunOS command line interpreter, exit to … exit and halt to shutdown FreeBSD. Remember to kill your qemu instance(s).

Networking your routers

Ok, one router it’s cool but useless alone. It’s time to make your virtual network! There are many ways to network your olive routers.

Olive to Olive using UNIX sockets

UNIX sockets create a TCP stream between two Qemu instances with one a client and the other a server. Apparently this method creates duplicate packets sometimes.

qemu R1.img -m 96 -nographic -daemonize -serial telnet::2001,server,nowait \
-localtime -net nic,vlan=1,macaddr=00:aa:00:60:01:01,model=e1000 \
-net socket,vlan=1,listen=:6000
 
qemu R2.img -m 96 -nographic -daemonize -serial telnet::2002,server,nowait \
-localtime -net nic,vlan=1,macaddr=00:aa:00:60:01:02,model=e1000 \
-net socket,vlan=1,connect=127.0.0.1:6000

Olive to Olive using UDP tunnels

UDP tunnels are mainly used to connect to Dynamips/GNS3 emulated routers but can also be used as a more reliable way to connect two Qemu olives together but this can result in much lower latency connections as well.

qemu R1.img -m 96 -nographic -daemonize -serial telnet::2001,server,nowait \
-localtime -net nic,vlan=1,macaddr=00:aa:00:60:01:01,model=e1000 \
-net udp,vlan=1,sport=10000,dport=10001,daddr=127.0.0.1
 
qemu R2.img -m 96 -nographic -daemonize -serial telnet::2002,server,nowait \
-localtime -net nic,vlan=1,macaddr=00:aa:00:60:01:02,model=e1000 \
-net udp,vlan=1,sport=10001,dport=10000,daddr=127.0.0.1

Olive to real world using TAP interface

One way to connect an interface on your Olive with a real Ethernet NIC is to use a bridge and the Qemu tap option.

Linux:

It is required that you have the generic TUN/TAP driver either built-in to your kernel, or available as a module. To check the availability of this module do the following:

ls -la /dev/net/tun

If you get no such file or directory, try doing a modprobe tun. It should then appear in the lsmod output.

One way to connect an interface on your Olive with a real Ethernet port is to use a bridge and the net -tap option. This requires you to have the generic TUN/TAP driver either built-in to your kernel, or available as a module. To check the availability of this module do the following:

Let’s say you started the emulator with the following:

qemu R1.img -m 96 -nographic -daemonize -serial telnet::2001,server,nowait \
-localtime -net nic,vlan=1,macaddr=00:aa:00:60:00:01,model=e1000 \
-net tap,vlan=1,script=no

Note the vlan=1 and -net tap options. This basically connects your Olive’s en0 to a virtual tap interface (usually tap0) on your host system. Start up Qemu, and once the emulator is running, proceed to the next step. You’ll need to start up the emulator as root, or change the ownership or permissions on /dev/net/tun.

We’re going to need to now bridge the tap0 interface to another Ethernet interface on the host system. To do this, we’ll utilize the bridge capabilities of Linux. First, get the bridge utilities:

sudo apt-get install bridge-utils

Let’s assume you want to connect en0 on the Olive to eth1 on the host system.

Do the following as root:

brctl addbr br0
brctl addif br0 eth1
brctl addif br0 tap0

This creates a bridge device, br0, and binds the two interfaces to it. Right now everything is still down. Let’s bring it up…

ifconfig eth1 up
ifconfig tap0 up
ifconfig br0 up

Now the bridge and member interfaces should be up. Don’t assign any IP addresses to either of the member interfaces. If you want to, you can assign something to br0 if needed. (br0 is analogous an SVI in the Cisco world) To see the status of the bridge, do the following:

brctl show
bridge name     bridge id               STP enabled     interfaces
br0             8000.000cf19ce06c       no              eth1
                                                        tap0

Now, assign an IP address to the em0 interface on your Olive, and it should be online. You are also free to tcpdump on the bridge or member interfaces, for debugging. All of this can probably be put into a Qemu interface script, so you can remove the script=no option, and make it a little more automatic.

Your kernel might have ethernet filtering (ebtables, bridge-nf, arptables) enabled, and traffic gets filtered except ARP and STP. The easiest way to disable this is to go to /proc/sys/net/bridge. Check if the bridge-nf-* entries in there are set to 1; in that case, set them to zero and try again. More information on bridges available here.

# cd /proc/sys/net/bridge
# ls
bridge-nf-call-arptables  bridge-nf-call-iptables
bridge-nf-call-ip6tables  bridge-nf-filter-vlan-tagged
# for f in bridge-nf-*; do echo 0 > $f; done

Windows:

Using OpenVPN you can create several tap interfaces with “Add a new TAP-Win32 virtual Ethernet adapter” and rename them with something like ‘Tap1′, ‘Tap2′ and so on

Let’s say we have created 1 Tap interface and renamed it as Tap1. Right click this Tap1 interface on Windows Control Panel – Network Connections and give IP address for example 10.1.1.1/8.

Now you can start Qemu with the -net tap option and ping the interface from your Olive:

qemu -L . -m 96 -hda R1.img -localtime \
-net nic,vlan=1,macaddr=00:aa:00:60:01:01,model=e1000 \
-net tap,vlan=1,ifname=tap0

Mac OS X

On Mac OS X, download and install the TunTap package.

qemu R1.img -m 96 -nographic -daemonize -serial telnet::2001,server,nowait \
-localtime -net nic,vlan=1,macaddr=00:aa:00:60:00:01,model=e1000 \
-net tap,vlan=1,ifname=tap0,script=no

We need to give this inter­face an ip address:

sudo ifconfig tap0 198.18.0.250/24 up

Olive to real world using PCAP/LACP

In the patch provided in this howto, there is an option to use PCAP or LCAP libraries to bridge directly to a physical interface. You will probable need to run Qemu under Administrator privileges. Please also note that it will stop any other traffic on your interface.

For PCAP:

qemu R1.img -m 96 -nographic -daemonize -serial telnet::2001,server,nowait \
-localtime -net nic,macaddr=00:aa:00:60:01:01,model=e1000 \
-net pcap,ifname=eth0

For LCAP:

qemu R1.img -m 96 -nographic -daemonize -serial telnet::2001,server,nowait \
-localtime -net nic,macaddr=00:aa:00:60:01:01,model=e1000 \
-net lcap,ifname=eth0

Please note that you have to configure an IP address your physical interface before being able to communication between your routers. Also I didn’t test PCAP/LCAP on Windows.

Olive to Dynamips or Pemu

The lastest patch also added a udp option to allow networking to a Dynamips or pemu.

qemu R1.img -m 96 -nographic -daemonize -serial telnet::2001,server,nowait \
-localtime -net nic,vlan=1,macaddr=00:aa:00:60:00:01,model=e1000 \
-net udp,vlan=1,sport=10000,dport=10001,daddr=127.0.0.1

Then in your dynagen .net file

[[router Cisco1]]
fa0/0=NIO_udp:10001:127.0.0.1:10000

Olive to GNS3

Under GNS3, you can create a “Cloud” and configure a NIO UDP (you can add as many NIO UDP as you want). The “Cloud” will be your interface between Olive and GNS3, you can link a firewall or a router per NIO UDP.

Of course, you can do the same with other NIOs like NIO TAP to connect to your olive using a TAP interface.

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