Ubuntu image for EVE-NG – Python for network engineers

Lately I’ve started working more and more with EVE-NG to test various network scenarios, automation and in general to try and learn something everyday.

If you’re familiar with EVE-NG, you know where to find various Linux images which you can download and install . Very helpful indeed, however all of them are coming without any pre-installed tools which I need for network oriented tests. I need Python, IPerf, Ansible, various Python libraries for network automation, etc.
Basically every time when I setup a new lab in EVE-NG, I need to make sure that the Linux image has a connection to Internet to download all these tools. Doable, but too much time consuming.

Lately EVE-NG has the Pro version, where you have Docker images which support some of the tools for a network engineer needs to test automation. If you already have EVE-NG Pro, then maybe this is a bit redundant. However if you’re still using the Community version, it may sounds interesting.

I’ve developed the Ubuntu (18.04) image using the same tools that you can find in my Docker image (Ubuntu 16:04 Pfne):
* If you’re not sure what I’m talking about, please read my previous post.

  • Openssl
  • Net-tools (ifconfig..)
  • IPutils (ping, arping, traceroute…)
  • IProute
  • IPerf
  • TCPDump
  • NMAP
  • Python 2
  • Python 3
  • Paramiko (python ssh support)
  • Netmiko (python ssh support)
  • Ansible (automation)
  • Pyntc
  • NAPALM

The image is hosted on my Firstdigest Project at Sourceforge.
If you are in a hurry, download directly using this link: Ubuntu 18.04 Pfne for EVE-NG.

For convenience here are the steps, but if you run into trouble be sure to check the EVE-NG Documentation.

  • Download the image
  • Using favorite SFTP Client (WinSCP, FileZilla) connect to your EVE-NG and upload the image to the location: /opt/unetlab/addons/qemu/
  • Connect via SSH to your EVE-NG machine and go to location:
cd /opt/unetlab/addons/qemu/
  • Unzip your uploaded image file.
tar xzvf linux-ubuntu-server-18.04-pfne.tar.gz
  • Remove the archived image file (be sure to have a copy somewhere to avoid you have to download it again)
rm -f linux-ubuntu-server-18.04-pfne.tar.gz
  • Fix permissions
/opt/unetlab/wrappers/unl_wrapper -a fixpermissions

The image comes with the following predefined username and password (security was not the point here):

User: root
Password: root
User: pfne
Password: pfne

With this image you have everything ready for your tests. You want to test QoS? Just design a network and two (client / server pair) machine using this image and push some packets with IPerf. Or maybe you want to test some automation. Here you have it, just start playing with.

Btw, I assume you have the EVE-NG installed. If not and you’re into learning topics, I’ll advise you to install this great application. You can start with Community version which is free (and honestly has enough features for most of the self-teaching engineers out there) and if you feel like go with the Pro version.

Let me know if you find it useful. In case of problems, please comment and I’ll try to help in my spare time.

Docker image – Python for network engineers

Lately I’m looking more and more into Python, with respect to automation implementations useful for network engineers. In the learning process I’ve used different materials, like the excellent video trainings Python Programming for Network Engineers from David Bombal which are available free on Youtube.

This training in particular relies on a Ubuntu Docker image in order to support Python learning following interaction with Cisco devices in GNS3. Everything is great, just that the image doesn’t contain all necessary tools (like Paramiko, Netmiko, Ansible…). As you can guess, whenever you close / open the Project in GNS3, all the installed packages installed in the Ubuntu Docker image are gone.

Since we’re talking automation, I got bored to install the necessary tools everytime I wanted to start a new project or I had to close GNS3 for some reason. I’ve tried to find a Docker image that suits my needs, but I couldn’t (please point me to one if you know it).

So, I’ve build a Docker image, based on Ubuntu 16.04, which contains the necessary tools to start learning Python programming oriented for network engineers:

  • Openssl
  • Net-tools (ifconfig..)
  • IPutils (ping, arping, traceroute…)
  • IProute
  • IPerf
  • TCPDump
  • NMAP
  • Python 2
  • Python 3
  • Paramiko (python ssh support)
  • Netmiko (python ssh support)
  • Ansible (automation)
  • Pyntc
  • NAPALM

The above list can be extended, but I would like to keep it to the minimum necessary (I want to keep the image size at decent level).

If you’re interested, please find the image at: https://hub.docker.com/r/yotis/ubuntu1604-pfne/, or you can download it:

$ docker pull yotis/ubuntu1604-pfne

I’ve tested the image for couple of days and it works fine. However if something doesn’t work as expected, please let me know and I’ll try to fix it.

For those using GNS3 is possible to import the image above directly into GNS3 using the PFNE Appliance.

F5 BIG-IP Plugin with Firefox 52 workaround

It’s not news anymore that Mozilla is stopping support for NPAPI (Netscape Plugin API). With the release of Firefox 52 version, I believe that only Flash plugin is enabled by default.

I’ll skip the discussion about NPAPI plugins and Mozilla’s decision to stop the support, however the reality is that for me it has a strong impact in certain areas. One of this areas is the F5 BIG-IP, specifically the APM and possibility to launch Application (like RDP) from the Webtop interface.

I’m relying heavily on a F5 BIG-IP VE machine to connect to my home lab when I’m remote. The Webtop functionality gives me the possibility to use only a Browser to connect to my applications at home, keeping me away from any F5 client installation on the machine that I use. Usually this machine is my MacBook or PC, and the F5 client installation should not be a big thing, however I like the clientless option.

The F5 Webtop functionality is possible due to a NPAPI plugin called “F5 Network Host Plugin” which usually installs in the browser when you access the F5 APM. So yes, you still need to install something, but this browser plugin is easy to install / remove when compared with a F5 client.

One morning I wake up to find out that my Firefox browser was silently upgraded in the background and instead of being able to launch an Application from the F5 Webtop interface I see this:

Useless to say that the plugin was already installed and everything seemed to be fine. Googling around I could find a lot of information why is not working, but no workaround until I read this article on the F5 DevCentral page.
F5 is aware of the problem, they are working on a solution but so far everything points out to use of the F5 client.

Until Firefox 51 everything was still fine but with the release of Firefox 52 you will get the error showed above. Long story short, for now, there is a workaround which suppose to work fine on Firefox 52 and the upcoming 53 version.

You need to create in Firefox 52 a configuration parameter called “plugin.load_flash_only” and set the value to “False”. Remember that this parameter is not there, so don’t just search for it…create it.

  1. Head to the Firefox URL bar and type about:config.
  2. Accept the responsibility that you’ll not destroy your Firefox installation.
  3. Right click
  4. Chose New > Boolean from the menu
  5. In the newly open window type: plugin.load_flash_only
  6. Set the value to: False

In the end you’ll see something like this:

Remember that I said in the first line that only Flash plugin is still enabled by default? This setting reverse that setting, by saying that not only Flash plugin should be enabled.

Not sure what I’ll do for future. Not to upgrade Firefox 52 (and possible 53) to the next release is not a long term option and from security perspective is a disaster. To keep a parallel installation of Firefox just to reach my trusted URL…doable, but still a bit of a hassle. I hope F5 will come up with a solution.

Draw network diagrams online [2016 Edition]

In this post from 2011 I was explaining that my preferred online tool to draw network diagrams is LucidChart.com. Since then LucidChart.com developed really good and added constantly new features. Unfortunately with the new great additions some not so nice restrictions appeared for the free account.
Those restrictions (like 5 active documents) really make it difficult for me to work with this tool as I got used to a different style.

I’m not a cheap guy! If I would use this tool professionally there would be no problem to buy a subscription package, but at work Visio is saint (unfortunately) and the rest of the time, especially when I’m on my Mac, I just need a fast tool to draw brief network diagrams like for my blog or fast explanation to somebody online.

LucidChart.com is my recommendation if you rely on online tool to work with Visio documents. Last time when I checked their Visio import tool was doing a great job.

Back to this story, I was looking online for another tool when I came across Draw.io.

Draw.io doesn’t need an account creation, rather it just give you direct access to the tool.
Since you don’t have an account you cannot save your work on the application, but it does offer you the option to save on Dropbox, Google Drive or OneDrive online or directly on your machine.
Later you can open your document from any of these locations.

In terms of shape the tool is pretty generous and the Cisco ones, really important for me, are there:

draw.io

The tool is very easy to use, it gives you a Visio feeling (if you’re used with this Microsoft software) and works pretty fast for me.

I tried to open a Visio document from my machine…did not work that well:

draw.io-visio-open

Importing the same document did not work better:

draw.io-import-visio

It seems that in both cases the Riverbed Steelhead shapes loaded fine, but not the Cisco ones.

Well, I would like to see this working, but in the end nothing to complain. I explained already that I don’t need the online tool to work with Visio. It’s nice if it can, but not mandatory for me. I’ll try some more tests with different Visio files, who knows maybe it’s something wrong with my test file.

One feature which I would like to see is the ability to add your own shapes. Who knows maybe in the future.

If you know a better alternative to LucidChart.com that has a free option and you consider it better than Draw.io please let me know.

Cisco ASA packet capture showing bidirectional traffic flow

Recently I had to troubleshoot some communication issues via a Cisco ASA device and the packet capture on the IOS comes in handy for this task.

When you have a lot of traffic over ASA and you’re interested in a particular IP address, the basic packet capture lesson says that you should configure an access-list to limit the captured packets for the interesting traffic only.

Let’s assume that I have a particular interest for the traffic to and from the IP address 10.0.0.10.

I created a standard ACL to match only the traffic related to 10.0.0.10:

access-list TS standard permit host 10.0.0.10

Afterward I attached the created ACL to a packet capture on a particular interface (let’s call it “lan”).

capture TSHOOT access-list TS interface lan

You can find the above lines in almost any how-to regarding packet capture on Cisco ASA.

Checking the capture I noticed that traffic is unidirectional captured:

FW# show capture TSHOOT

4 packets captured

   1: 20:15:32.757010       802.1Q vlan#10 P0 192.168.0.10 > 10.0.0.10: icmp: echo request
   2: 20:15:33.759283       802.1Q vlan#10 P0 192.168.0.10 > 10.0.0.10: icmp: echo request
   3: 20:15:34.761374       802.1Q vlan#10 P0 192.168.0.10 > 10.0.0.10: icmp: echo request
   4: 20:15:35.823748       802.1Q vlan#10 P0 192.168.0.10 > 10.0.0.10: icmp: echo request

This is not enough to troubleshoot complex communication scenarios.

Ok, maybe the standard ACL is not enough, so I tried to use extended one where 10.0.0.10 is source on one line and destination on another:

access-list TS extended permit ip host 10.0.0.10 any
access-list TS extended permit ip any host 10.0.0.10

This should do it…just that it doesn’t.

capture TSHOOT access-list TS interface lan

ERROR: Capture doesn't support access-list  containing mixed policies

Hmm, maybe it does not work with two lines in the ACL. I removed one, same error.

I was looking around to find a way to do it, but I couldn’t. This is why I wrote this article. Maybe my googling skills are not so good, as I’m sure it has to be an example somewhere out there.

However, here how I did it.

I gave up using the ACL. No, I’m was not going to capture the entire traffic :) Instead, I used inline restrictions for the IP address that I’m interested in.

capture TSHOOT interface lan match ip host 10.0.0.10 any

The result looks good now:

FW# show capture TSHOOT

8 packets captured

   1: 20:19:07.222553       802.1Q vlan#10 P0 192.168.0.10 > 10.0.0.10: icmp: echo request
   2: 20:19:07.223392       802.1Q vlan#10 P0 10.0.0.10 > 192.168.0.10: icmp: echo reply
   3: 20:19:08.229953       802.1Q vlan#10 P0 192.168.0.10 > 10.0.0.10: icmp: echo request
   4: 20:19:08.230670       802.1Q vlan#10 P0 10.0.0.10 > 192.168.0.10: icmp: echo reply
   5: 20:19:09.229327       802.1Q vlan#10 P0 192.168.0.10 > 10.0.0.10: icmp: echo request
   6: 20:19:09.230121       802.1Q vlan#10 P0 10.0.0.10 > 192.168.0.10: icmp: echo reply
   7: 20:19:10.252321       802.1Q vlan#10 P0 192.168.0.10 > 10.0.0.10: icmp: echo request
   8: 20:19:10.253130       802.1Q vlan#10 P0 10.0.0.10 > 192.168.0.10: icmp: echo reply

The packet capture shows now bidirectional traffic flow.

I hope you’ll find this useful during troubleshooting.