Friday, September 26, 2014

PSA: “Shellshock”

PSA: If you use any form of *nix as your operating system – some form of Unix, Linux, or Mac OS X – and you have the Bash shell installed, you may want to see about updating it. This is because of a newly-disclosed critical vulnerability in it (dubbed by some “Shellshock”) that could potentially allow an attacker to execute arbitrary code with a specially formed attack. (If you're on Windows you're probably ok, unless [possibly] you're using something like cygwin, in which case you're probably tech-savvy enough to look up how to fix it.)

It's quite easy to check if your version of Bash is vulnerable: open up a terminal window and run:

> env x='() { :;}; echo vulnerable' bash -c "echo this is a test"

Should Bash be vulnerable, it'll return:

> env x='() { :;}; echo vulnerable' bash -c "echo this is a test"
> vulnerable
> this is a test

If it's not vulnerable, you should just get back “this is a test” and possibly a warning about Bash ignoring an attempted function definition. If it does return vulnerable, you'll want to see about updating your version of it as soon as possible (most [all?] of the major Linux vendors have released patches, and Apple is expected to do so soon). Basically, instead of a harmless “echo vulnerable” (which just prints the word “vulnerable” to the terminal), an attacker could potentially put a much more harmful command in there, which in the right circumstances could do a lot of damage.

One noteworthy feature of this bug is that it's apparently been around for something like twenty years (Bash is fairly old as software goes), so it's expected to be found in as incredible number of devices, including a large number of the servers that host the World Wide Web.

It's still early yet to see what will come out of this, but it's likely to be a serious security issue for quite some time due to the difficulty of getting everything patched.

(I was feeling creative tonight, though I may have been a bit too literal.)

Edit (9/27/14): I wasn't entirely happy with that version so I went back and played around with it some more and made a few more versions (and learned some useful lessons about Inkscape in the process). Here's the version I currently like the most:

Monday, September 15, 2014

Photo Fun with the Tropical Sun

One fun thing about living in the tropics is how there are days when the sun is directly overhead. When it happens is a function of your latitude, but if you live between the Tropic of Cancer and the Tropic of Capricorn, two days of the year the sun shines straight down around noon (exact time dependent on your longitude).

In Hawaii there's a local term (of comparatively modern origin) for it, Lahaina Noon. Lā hainā means “cruel sun” in Hawaiian (it's also the name of a town on Maui named for its famously dry and hot climate). There's a colorful ancient Hawaiian phrase for the time of noon generally, kau ka lā i ka lolo, an idiom that translated literally means “the sun rests on the brains.”

I unfortunately never seem to get around to actually going out and looking when it happens (in Hilo, the Lahaina Noon days are in May and July), but even now in September the sun still stands very nearly straight up in the sky around noon. I happened to notice the neat shadows it produced on the sign at the Smithsonian Astrophysical Observatory building across the street one day, and decided it was worth a picture:

According to the timestamp, this picture was taken at 12:41:44 PM on September 5th, 2014. In case you can't tell from the picture the letters are small metal shapes protruding out from the wall on little supports, which allows this neat interplay of light and shadow. Just another fun feature of living in the tropics. A hui hou!

Friday, September 12, 2014

Hiking Pololū Valley

Well, as you can see this post is a few days later than I'd originally planned, for which I apologize. Upon arriving at Pololū Valley, we were greeted with this lovely panoramic view:

You really want to click on this one to see it larger.
In this picture, Pololū Valley is on the right. We're now looking back down the coast towards Waipi‘o Valley, although it's around the bend in the coast and can't be seen from here (you'll notice there are some tiny rocky islands further down the coast that couldn't be seen from the Waipiʻo Valley overlook). Here's a smaller picture that focuses on the sea end of the valley:

You can see the flank of Mauna Kea sticking out behind those sea rocks.
As we descended the trail down the cliff face, we'd occasionally get glimpses further back up the valley. I usually avoid putting myself in pictures, but I had Graham take this one:

Hark! A valley! By this time, clouds had come in and were shrouding the head of the valley.
Thankfully the path was well-shaded for most of its length by the verdant overgrowth that hugged the steep walls of the valley like some overgrown moss carpet. From a lower switchback I got this vantage point of the beach:

For some reason this picture looks “cool” to me (as in “not warm”). I think it's all the blue.
And just because I love the view along the Kohala coast so much, here's a zoomed-in picture of it:

Again, that's Mauna Kea peeking out from behind the sea-cliffs there.
I think I can count four more valleys down the coast in that picture, but I'm not sure. A little further down the trail, a great vantage point and lucky break in the clouds gave us this sight:

Looking towards the head of the valley.
Finally, after perhaps half an hour's hike, we reached the beach, made up of moderately-sized rocks further back and gray sand at the water's edge:

Pololū Valley beach. Dangerous to swim at according to the signs, but nice.
You can see the curvature of the horizon! Probably just my lens, actually.
Wandering a few dozen meters inland we found the large pond we'd seen from above. I think this connects with the ocean at high tide, so I suspect it's brackish water. The ancient Hawaiians used to catch fish and raise them in ponds, and they may have done so here.

You can clearly see the clouds hovering at the head of the valley here.

Graham, inspired by the same sight.
Back beyond the beach there was a small forest of some kind of pine tree (at least, it had needles like conifers – I don't know what kind of tree they actually were). They were scattered thinly, and it was quite pleasant to walk in their dappled shade.

Eventually we reached our goal for the day, the southern wall of the valley where the rock once again rapidly rises to tower five hundred feet or more above the valley floor. Some of the cliffs further along the coast are even higher, I believe (among the highest in the world).

From there, along the curve of the beach, we could look back up the coast, which was quite pretty:

Looking back along the beach and up the coast.

That house in the picture at the top of the cliff sits at the trail head near where I took the panorama at the beginning of this post, to give you an idea of the positioning.

All in all, it was a really great hike, and I'm glad I went. It took us a while to drive there and back, but we weren't in a big hurry and it was perfectly doable in a day. The trail in and out was really quite reasonable given the steepness of the cliff face it was descending. And the weather was pretty much as perfect as it could be. Hopefully I'll be able to make my way out there again sometime. A hui hou!

Sunday, September 7, 2014

Getting to Pololū Valley

For Labor Day, me and my friend Graham decided to head to the north part of Hawaiʻi island and hike the trail into Pololū Valley. Pololū (meaning "long spear" in Hawaiian) is the northern-most of the seven major valleys that cut the northeast flank of the extinct volcano Kohala, which sits north of Mauna Kea. On our way, we stopped at Waipiʻo Valley, the southern-most of the seven valleys. These valleys all have very steep walls; there's a 4WD-only road down into Waipiʻo (the only way in other than by sea), but no vehicle roads into any of the other valleys.

This is a panorama I put together from a series of pictures taken at the Waipiʻo Valley overlook, at the end of the valley on its southern side. After stopping there we continued on to the town of Waimea, where we stopped for lunch at a local burger joint called The Village Burger (excellent food!), before continuing up along the road below the ridge of Kohala. The region of Kohala and the northern flank of Mauna Kea have a lot of cowboy culture, and the parking lot had some rather amusing signs:

Driving north from Waimea along the upper highway that runs below and parallel to the Kohala ridge, there's a pretty dramatic demonstration of the rain-shadow effect. Kohala is an old, extinct volcano, the north-east side of which collapsed in a land-slide that left it with a peak ridge running north-west to south-east and created the dramatic cliffs that end so abruptly at the sea as you saw in the first picture.

The prevailing winds in the Hawaiian archipelago come from the north-east, so most of the humid air condenses into rain as it encounters the north-east side of Kohala; very little makes it over to the west side (which is also why Hilo on the east side is wet and Kona on the west is dry). The road runs mostly parallel to the ridge and the line between wet and dry, as you can see in these pictures. As you drive north, on your right you have this view, looking up towards the ridge:

And on your left, running down to the sea on the west side, you see this:

(That's Kawaihae harbor on the shore there. I'm guessing the extreme haziness in the air on this side is vog from Kilauea being blown up around the west side of the island.)

Another cool sight you get to see on a clear day like we had is the vast bulk of Maui rising in front of you. I was actually quite surprised at how different Mauai appears from the summit of Mauna Kea, as that's usually the only place I see it from. The ʻAlenuihāhā channel between Hawaiʻi and Maui is only about 30 miles across, so it's not that far away.

This actually turned out to be a lot more photos of the drive up than I thought, so I'm going to put the photos from when we actually got to Pololū Valley into their post, hopefully up tomorrow. A hui hou!