Traffic Selectors on a Route-based VPN

This is an extremely long-overdue post, but I wanted to add a follow-up to the old blogpost Route-based VPN with Multiple Source/Destination Networks to a 3rd Party Device. While the previous method still works, it still had some drawbacks:

  • It required the use of ephemeral IP address, which can be a waste of IP space
  • It only worked if there was one destination network, as Next-Hop Tunnel Bindings (NHTBs) did not address which source network traffic came from

Traffic selectors were introduced as feature starting in Junos 12.1X46-D10 (SRX200, SRX1400, and SRX3k series) and Junos 17.3R1 (SRX300, SRX1500, SRX4k, and SRX5k series) for IKEv1. IKEv2 support was added in Junos 15.1X49-D100, meaning this is only available for the SRX300, SRX1500, SRX4k, and SRX5k series.


SRX – Configuring a DHCP Server

It’s been a while since I wrote up a new post, so I thought I would come back with a nice post about the changes in configuring DHCP Servers on the SRX’s. Since Junos 12.x a new DHCP process came out to help fix some long standing issues with the existing feature. In this post I will discuss the old configuration, some of the problems I would regularly encounter, and the configuration of the new DHCP process.


Packet Mode and Selective Packet Services

Packet mode enables a SRX firewall to act strictly as a router, forwarding packets from a source to a destination without tracking sessions. This is useful for an engineer in certain situations such as high throughput applications that do not need full firewall functionality, or asymmetric traffic flows. We can also enable this mode on interesting traffic which is called Selective Packet Services. More details on Selective Packet Services is available on the following PDF as well as the rest of this post.


Studying for JNCIE-SEC Exam

Many people have now asked me for advice on how to pass the JNCIE-SEC Exam, which is a great thing as it seems many people are working towards achieving the next level in their certification journey. This post will cover:

  • Exam Objectives
  • Studying Materials
  • Additional Advice

In later posts I will discuss specific methods/techniques from those objectives.

A shout-out and thanks goes to CentraComm supplying many of the study materials/gear, as well as the terrific support and encouragement many coworkers provided throughout this journey!

Exam Objectives

So let’s first talk about what to study in order to prepare for the exam. Since this is a practical exam there is no single resource that covers every single aspect of the test. That being said, there are several books I would strongly recommend reading first in order to address 95% of the exam objectives:

One more important thing to know – be aware of what features are available for the version of Junos you are using! Right now the exam is set for 11.1, so things such as GRE tunnels in chassis clusters are not available. You can find those feature listings in either the Feature Explorer or the Feature Support PDF.

Studying Materials

You will absolutely need to get at least 2 SRX’s of the same model in order to set up chassis clustering and understand all the options for the clusters. In addition one of the units needs to be a High Memory unit in order to test UTM functionality. Obviously, the more the merrier is recommended in this case. The additional benefit of using the branch series is that they are extremely portable. I could fit my equipment into my carryon bag, and with the right cables/powerstrips it was extremely easy to set up a new mock lab anywhere I traveled. My lab was as follows (picture below):

  • 2x SRX-210’s
  • 3x SRX-100’s
  • 1x EX2200-C

Other Advice

The nearest testing site for me was in Herndon, Virginia so that required booking a flight. I actually left two days early to get situated in Herndon, and to get one last day of good studying in before the exam. It turned out to be a blessing in disguise as the plane landed several hours late due to storms! A 4-hour flight turned into an 8-hour ordeal due to the weather. Trying to get through an ordeal like that the day before the exam would have been extremely unpleasant, and add unnecessary stress to an already stressful exam.

In terms of how long to study, I did nothing but read for about a solid month prior to using the lab gear. The books mentioned above provided a good solid background to all the functionality inside the SRX’s. From there I would go through the exam objectives and create scenarios to reinforce understanding of a particular piece of technology. One of the important things to remember here is that building out complicated networks still require fundamental knowledge in the basics. For an example if you do not understand how to create/troubleshoot a simple VPN tunnel or how the SRX’s negotiate both phases of the tunnel, then you will struggle at this exam. If you don’t know how to perform a certain task, then take a look at the vast wealth available on the Internet. Here are a couple of sites that I would refer back to constantly:

Take your time when going through the exam, and make sure you review your configurations after you have completed the exam. Even after reviewing my configs there were still minor errors that would have cost dearly on the final scoring.

Lastly, ask the proctor questions if you’re unsure of what is required on an objective. The proctor will not be able to tell you the answer if you are stuck at a certain point, but they can provide valuable guidance on what needs to be done in your configurations.

Hopefully this will help you in your journey to achieving the JNCIE-SEC certification. Feel free to ask questions here, and stay tuned for more posts on how to configure many of the objectives for this exam.