Virtualbox VLANs in Ubuntu

Wanted to add quick note about VLANs, VirtualBox, and Ubuntu.

Virtualbox does VLANs a little differently on Ubuntu than other hypervisors. In order to get a VLANs working for a Virtualbox VM, you have to create a subinterface that is for a specific VLAN (of course, assuming your NIC supports 802.1q tagging). To create a subinterface in Ubuntu, follow the instructions here:

Then in Virtualbox, you set the network interface to ‘bridged mode’, then select the subinterface. Assuming your new subinterface is permanent, the VM will use that subinterface and be within that VLAN.

I’m not entirely sure how to accomplish this for Virtualbox on Windows. It would seem like you would need a separate physical interface, especially for Windows 10 and probably others.

Unrelated note: Virtualbox on Windows 10 is horrible, and so is the native Hyper-V, but that’s for another post, maybe.

Edit (20180705): A few years later, and I can honestly say VirtualBox on Windows 10 is stable now, and has been for awhile. Felt the need to update this. :-p

Skill Atrophy

One of the greatest threats to a young IT professional is skill atrophy. You work hard at developing a skill set over a given period of time, and you even go so far as to earn a certification in such a skill set — and then you quit using it.

The old appropriate is appropriate here: “Use it or lose it.”

Recently while working at a site, and much to my frustration, my skills in router and switch configuration — even just layer 2 and 3 protocols — had started to atrophy because I hadn’t touch a device in five months — then bam! I’m setting up not just layer 5-7 devices, but I’m also setting up layer 2 and 3. I’ve been working so long in the higher layers that I started to forget basics in layer 2 and 3.


Layer 3 Switch


The hard part is that it was something rather ridiculous. It was a layer 3 switch, and turned the gateway port into a routed port instead of a switched port, thinking that I would separate out a server farm from the layer 2 network that it was attached to through that port. Nothing was getting DHCP requests on this switch and it was frustrating me to no end, not to mention I had to local techs looking over my shoulder and just standing there wondering what was going on! In the end, it was by getting help from my boss and co-worker that lead me down the road to figure out what I had been doing wrong.

So how does one prevent skill atrophy? The obvious answer is to practice, but that may not always be an option, especially if you’re in an environment where the work constantly changes and you’re insanely busy (that’s my excuse at least). Perhaps doing Packet Tracer simulations — for CCNA folks like myself — would be really helpful here.

Another idea is just good documentation, even trying to take a snapshot in time to see what you were doing. Copy your configs and annotate the configs to explain what the heck you were thinking — even encouraging this at your company so that other techs, or future techs, can get an idea of what’s going on.

Asking for help is always an option, especially if you’re really stumped. Time wasted can never be taken back (it’s a sunk cost), so realizing you’re failing bad early on can help mitigate future problems. To quote Freakonomics writer Steve Levitt, “Fail quickly.” However, at the same time, realize your failure is also a learning and/or reinforcement opportunity and will make you a better IT professional.

And of course, there’s also a good IT professionals google-fu, but you should be relying on that constantly, otherwise, are you learning any of this stuff?

All this being said, I’ve learned my lesson and I’m better because of it.