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In this tutorial we are going to run a simple experiment in GENI, using the Omni command line tool. We are going to take advantage of the Layer 2 links between nodes and run a non-IP experiment.

This is the topology of our experiment:

Before we start with the Omni tutorial, please follow these steps:

  1. Login to the VM
  2. Run Firefox
  3. Open all bookmarks under the Intro to Omni bookmark folder
  4. Open a terminal window

1. Configure Omni

Omni is a tool that will help you reserve resources in GENI, using your GENI account. The first step is to load into Omni your account information. Omni uses a configuration file, and there is a script that will automatically generate the file with some default options and place it in the default place of ~/.gcf/. Follow these steps:

  1. In the web browser login to using the information in the paper slip
  2. On the menu on the left, press Download your cert
  3. Select the option about downloading as a pem file.
  4. Press Ctrl-s to save this page. Type ~/.ssl/geni_cert.pem, if file already exists replace it.
  5. In the terminal type:
    This should configure your Omni, with your downloaded certificate and create an ssh key pair for logging in to nodes.

Tip: When prompted for a passphrase, type the passphrase in your slip. You might be asked for a passphrase multiple times. Note: If you have taken other tutorials, you might have configured omni with other accounts, select to overwrite existing setting if asked.

The output should look like:

{'framework': 'pg', 'configfile': '~/.gcf/omni_config', 'plkey': '~/.ssh/geni_pl_key', 'cert': '~/.ssl/geni_cert', 'verbose': False}
INFO:omniconfig:Using configfile: /home/geni/.gcf/omni_config
INFO:omniconfig:Using certfile /home/geni/.ssl/geni_cert.pem

INFO:omniconfig:Private key stored at: /home/geni/.ssh/geni_key
Enter passphrase: 
INFO:omniconfig:Public key stored at: /home/geni/.ssh/
INFO:omniconfig:Added to /home/geni/.ssh/config this line:
	'IdentityFile /home/geni/.ssh/geni_key
INFO:omniconfig:Wrote omni configuration file at: /home/geni/.gcf/omni_config

1a. Look around the omni_config file -- Optional

Open the file ~/.gcf/omni_config using either vim or emacs. Close to the top of the file you will see two parameters called default_cf and users. Your username should be at least listed in the user section. Look for the sections in the file that are named [pg] and [<username>].

In the [<username>] section, the information need for logging-in to reserved compute resources are provided. It includes your unique user URN and a public key that would be uploaded to the hosts that you reserve.

In the [pg] section you configure Omni to use your personal information. The cert and the key attribute point to files that we have manually downloaded from This is equivalent to the Download action of Flack.

Another interesting section to look at is the [aggregate-nicknames] sections. Flack already knows the URL for all the AMs and present you a list of AMs to choose from using a short, descriptive name. In Omni a user is required to pass the URL for each call to the GENI AM API. In this section the user gets a chance to provide short descriptive names to the URLs that are easier to memorize and use.

2. Clear the passphrase from your cert

When Omni talks to different authorities in GENI, it will need to identify you as a valid GENI user, so it will ask you for your passphrase multiple times. To save time during the tutorial, we are going to remove the passphrase from your cert and your ssh key. There is a script to clear the passphrases.

  1. In the terminal run 
    Use the passphrase given to you in the paper slip, you might be prompted for a passphrase multiple times make sure you always use the same passphrase. The output should look like
    Do you want to remove the passphrase from your cert (/home/geni/.ssl/geni_cert.pem) [Y,n]?y
    INFO:clearcert:The encoded certificate file is backed up at /home/geni/.ssl/geni_cert_enc.pem
    INFO:clearcert:Removing passphrase from cert...
    Enter pass phrase for /home/geni/.ssl/geni_cert.pem:
    writing RSA key
    INFO:clearcert:Change permissions of /home/geni/.ssl/geni_cert.pem to 0600
    Do you want to remove the passphrase from you ssh-key (/home/geni/.ssh/geni_key, key used to login to compute resources) [Y,n]?y
    Enter PEM pass phrase:
    Enter passphrase:
  2. Add the key to the ssh agent
    ssh-add ~/.ssh/geni_key
  3. Verify that you have the necessary credential and key files
    ls ~/.ssh ~/.ssl
    The output looks like :
    geni@geni-vm:~$ ls ~/.ssh ~/.ssl
    config  geni_key
    geni_cert_enc.pem  geni_cert.pem
geni_cert.pem Cleartext certificate, i.e. does not require any passphrase
geni_cert_enc.pem Encrypted certificate
geni_key The private key that you will use to login to the nodes The corresponding public key that will be uploaded to the nodes

Note: You might see more files than the ones listed above, which are probably backup files from configuring omni, or files from other tutorials.

3. Test Omni setup

In order to test that our configuration is correct, you can issue a getversion command. For this step we have used PlanetLab's AM, but you can use any Aggregate Manager(AM).

  1. In the terminal type: getversion -a plc
    In GENI each AM can be contacted using a specific URL. In order to make it easier to talk to AMs, Omni uses nicknames; i.e. it maps each URL into an easy to remember nickname. For example the PlanetLab AM listens for requests at, however you can use the nickname plc to refer to that URL. Nicknames are defined in each user's omni_config file.

For the rest of the tutorial we are going to use aggregate nicknames.

4. Create an experiment using Omni

5. Run your experiment

Now that resources are ready we can start running our experiment. We will first start by logging in to our reserved nodes.

5a. Logging Into the nodes -- Omni Scripting

Depending on the Aggregate the login information are either part of the sliverstatus call, or as part of the manifest rspec, i.e. returned from the listresources call. Omni comes with a script that makes it easy to gather all this information.

  1. In the terminal run: -a pg-utah <slicename>
    The script will return the actual command that you would need to use for logging in.
  2. Login to both nodes by copy-paste the commands from the output of the script.

5b. Send IP traffic

The first simple experiment that we will run is to verify the IP connectivity between our hosts.

  1. Check the interfaces of your nodes. In the terminal type:
    You should see at least two interfaces:
    • The control interface. This is the interface from where you access the node, e.g. ssh into your host. The control interface is mainly used for control traffic, i.e. traffic for controlling the node and the experiment. The control interface usually has a publicly routable IP.
    • The data interface. This is the interface that is used for sending experimental traffic. This is the interface that connects to the other hosts of your experiment through GENI. The links between these interfaces are the ones that allow you to run non-IP experiments.
  2. Note the name and the MAC address of the control and of the data interface for each node. The data interface is the one that has an IP that starts with 10.
  3. From the client ping the server. From the xterm that is logged in to the client type :
      ping server -c 5
    Note: You can use the name that is assigned to the host to directly ping the host, you can also ping using the IP of the data interface of the node. An example output should look like :
    [[inki@r2 ~]$ ping server -c 5
    PING ( 56(84) bytes of data.
    64 bytes from icmp_seq=1 ttl=64 time=1.95 ms
    64 bytes from icmp_seq=2 ttl=64 time=2.27 ms
    64 bytes from icmp_seq=3 ttl=64 time=2.04 ms
    64 bytes from icmp_seq=4 ttl=64 time=1.95 ms
    64 bytes from icmp_seq=5 ttl=64 time=1.72 ms
    --- ping statistics ---
    5 packets transmitted, 5 received, 0% packet loss, time 4005ms
    rtt min/avg/max/mdev = 1.728/1.992/2.278/0.179 ms

5c. Send non-IP traffic

GENI provides the capability of running non-IP experiments, since you can connect your hosts at Layer 2. For the purpose of this tutorial we have installed in all the hosts a very simple Layer 2 ping program that sends packets using a custom ethernet type.

  1. Disable the IP in your nodes. First of all we are going to completely disable IP on our nodes. In each of the terminals type:
    sudo /sbin/ifconfig <data i/f name>
    Note: Be extra careful to bring down the IP on the data interface, bringing down the IP on the control interface means that you will lose connectivity to your host.
  2. Try again to ping from the client to the server. In the xterm of the client type:
    ping server -c 5
    This time the ping should timeout.
  3. Start the Layer 2 ping server: In the server xterm, type:
    sudo /usr/local/bin/pingPlusListener 12345
  4. From the client try to ping the server at layer 2. You will need the mac address of the data interface of the server and the name of the data interface of the client. In the xterm of the client, type:
    sudo /usr/local/bin/pingPlus <server data mac addr> <client data i/f name> 12345

The result should look like :

[uncusr20@client ~]$ sudo /usr/local/bin/pingPlus 02:00:9B:48:3E:20 mv1.1 12345
RQ:'5582+2067' to 2:0:9b:48:3e:20.
RQ:5582+2067 from 2:0:3e:15:6c:ab.

Congratulations you have run a Layer 2 experiment in GENI!

6. Cleanup resources

Although all your reservations, have expiration times, you should always release your resources once you have completed your experiment to make them available to other experimenters.

  1. In the terminal, where you have been running your omni commands do: deletesliver -a  pg-utah <slicename>

7. Wrap up

Congratulations, you have finished the tutorial! Now you are ready to design and run your own experiments. Don't hesitate to email us with any questions you might have.

7a. Fill out the tutorial survey

We love to hear what you think so that we can improve the tutorials in the future. Please complete the online survey and get a temporary GENI tatoo!

7b. Get Your Own Account

The accounts, that you used in the above steps will be deactivated after the tutorial. If you do not already have an account at GPO's ProtoGENI cluster, you should can follow these instructions to get an account and start using GENI.