Sam Range

Athena is the distributed computer system used at MIT. It began in 1983 as a joint venture between MIT, IBM, and DEC. It shaped the development of desktop computers and is still used extensively at MIT and several other universities. On campus, Athena can easily be accessed at Athena terminals, located in Athena clusters and interspersed around campus.

For students off campus, MIT provides remote access to the system. This is the first installment of a guide to running Athena from your home computer. It guides you through logging in to Athena using SSH and Linerva. It is a work in progress, so I’ll modify it should clarifications or changes be useful. Future parts will address Zephyr, Barnowl, and GNU screens. This guide assumes you already have a Kerberos username and password (obtained by following the instructions in your Next Big Mailing), an internet connection, and a computer running Windows, Mac OS X, or Linux.

What is SSH?

SSH (Secure SHell) is a communications protocol that allows parties to communicate securely over the internet. Here, SSH is used to let you login to Athena securely, using your Kerberos login.

In order to login to Athena using SSH, you’ll need an SSH client. This will be different for different operating systems, so follow the one that’s appropriate for you.

SSH for Windows

PuTTY is an open source (MIT License) SSH client for Windows. You can find it at the PuTTY download page. You’ll want the first binary “putty.exe”. Download it to somewhere you can find it, like your desktop.

Run the file you downloaded (no installation required) and you’ll get a screen like this, but without the “host name” field filled in.

We’re going to connect to MIT using Linerva, a portal for accessing Athena remotely. So, in the “host name” field, type “linerva.mit.edu”. We want to use SSH, so select “SSH” under “connection type,” if it’s not already selected. Finally, click “Open” to initiate the SSH connection.

A new window will appear asking you for your username. Enter your Kerberos username and press enter. Then, it will ask for your password. Enter your complete password, including punctuation and capital letters if appropriate. Linerva does not show asterisks as you type (so someone peeping over your shoulder doesn’t know how many digits are in your password), but it is still receiving what you type in, so don’t be perturbed. When you’re finished, press enter again, and if you provided the correct information, you’ll be logged in.

This is an example. If Susan Hockfield were logging into Linerva using PuTTY (I don’t know if she does), this is what she would see.

Do note: some of the messages displayed when you log in may be different from what you see above.

Now, you are logged in to Athena. Skip to the Athena Primer below for an introduction.

SSH for Mac OS X and Linux

Both Mac OS X and Linux share a common ancestry with Athena, so they come with the tools for communicating with SSH. You will have to open the terminal, which can be found in OS X by going to the Applications -> Utilities folder and opening “Terminal”. For Linux, different distributions will place the terminal in different locations, but you’re probably familiar with it. If not, Google “[your distribution] terminal” and you should find it.

With the terminal open, we will use the SSH command and log in to Linerva, a portal for accessing Athena remotely. Type “ssh [your username]@linerva.mit.edu”, where “[your username]” is your Kerberos username. For instance, Susan Hockfield would type “ssh hockfield@linerva.mit.edu”. Then, press enter. You will be prompted to enter your Kerberos password.

Enter your complete password, including punctuation and capital letters if appropriate. Linerva does not show asterisks as you type (so someone peeping over your shoulder doesn’t know how many digits are in your password), but it is still receiving what you type in, so don’t be perturbed. When you’re finished, press enter again, and if you provided the correct information, you’ll be logged in.

Athena Primer

The Athena command line interface (CLI) is extremely similar to the one used in OS X and Linux, so if you’re already familiar with one of those, you should be right at home.

The command line interface is a bit different from the now-conventional graphical user interface (GUI), like the ones used in Windows, OS X, or desktop Linux distributions. Instead of having icons to click with your mouse, you type commands, press enter, and the computer executes the command. This system was ubiquitous in the early days of computers and is still widely used in all kinds of computing environments, such as web servers, corporate payroll systems, and supercomputers. However, if you’re unfamiliar with it, it requires some adjustment.

First, try a simple command, such as the “echo” command, which prints the words you instruct onto the screen. Type ‘echo “Hello World!”‘ without the outside quotes and press enter. Athena will execute your instruction and repeat “Hello World!” After it does so, it will have completed your instructions, so you will see a flashing cursor as it waits for more instructions. As you type various commands into the CLI, you will continue scrolling down the screen. You can review the history of instructions you have given by scrolling up.

Athena has a file structure similar to the operating system you’re used to, with files tucked away inside nested folders.When you log in, Athena places you in your home folder. This is the folder on Athena where you can place files. It is accessible from any terminal in Athena.

While you’re in the folder already, you obviously can’t see icons for the files and folders inside it. So, there’s a command to display the contents of the folder you’re in. Type “ls” and press enter, and you’ll see a list of everything in the folder. By default, there’s a file called “welcome”. To open it, we’ll use nano, a lightweight text editor that comes with Athena. Type “nano welcome” and you’ll see something like this.

Nano shows one page of text at a time. You can scroll using the arrow keys or Page Up and Down. If you’d like, you can edit the text in the welcome file, or you can just read it. When you’re done, you’ll want to exit the program. Along the bottom, you can see various commands you can give nano. You want “Exit”, which is accessed by pressing “^X”. Here, “^” means Control, so press Ctrl+x to exit. If you made changes, nano will ask if you want to save them. Press “y” or “n” to indicate “yes” or “no”.

Now you’re back at the command line with a blinking cursor waiting for instructions. You’re still in your home folder, but let’s change that. To create a new folder called “demonstration” for us to use, type “mkdir demonstration”. The “mkdir” (short for “make directory”) command creates a folder, and you type the name you want to give the folder after the command – in this case “demonstration”. Press enter to run the command and the folder will be created. You haven’t told Athena to change your directory, so you’re still in your home folder. Enter “ls” again and you’ll see the “demonstration” folder you made.

To move into that directory, you’ll use the “cd” (for “change directory” command). Enter “cd demonstration” and you’ll move into the “demonstration” folder. The text before your cursor will change to reflect this. Now, we’ll create a file, using nano again. Type “nano” to start the program. Nano works like a normal text editor, except without a mouse. Type some stuff – maybe your favorite food or the color socks you’re wearing – until you’re satisfied. Now, we’ll exit, again using Ctrl+x, and nano will ask if we want to save our work. We do, so type “y” for yes. It will ask for the name we want to give the file. Type “test” and press enter. Nano will close and the file will be saved to the “demonstration” folder. You can see it by typing “ls” again.

Now we’ll delete a file. The “test” file isn’t very useful, so we’ll get rid of it. Type “rm test” and press enter. “rm” is short for “remove” and deletes the file or folder you specify. If you type “ls” again, you’ll see that “test” is gone.

Edit (6/21/09 6:32 PM): If you’re a curious soul like Divya ’13 and choose to name the file something like “lovely foods” with a space, you’ll have to include quotes to tell Athena it’s a single file. ‘rm “lovely foods”‘

Now, we’ll get rid of the “demonstration” folder. To move back into the home folder, type “cd ../” and press enter. “cd” is the change directory command, and “../” specifies the folder above you. Slashes are used to divide folders, so this can be repeated. If you were hypothetically in a folder “coursework/6.01/algorithms/sorting”, you could get back to your home directory by typing “cd ../../../../”. Now, you’re back in your home folder, and you want to get rid of “demonstration”, so type “rm -r demonstration” and the folder will be removed. Note: “rm” only removes single files. To tell Athena you want to delete a directory, use the “-r” option as shown.

Now, you’re back to your home folder and things are back to normal. If you enter “ls” again, you’ll see that the “demonstration” folder is gone. You’ve just created, moved between, and deleted files and folders in Athena.

If you find errors in this procedure, email me at “namu” [at] “mit.edu”. Include the specifics and I’ll get things sorted out. I’ll post further parts explaining Zephyr, Barnowl, and GNU screens.

Edit: part two is now online.

I just got my first bounce flash, the Nikon SB-400, and I’m in love. This makes me rethink flash altogether.

I hope to get this out in the field later today, but for now, I just took a picture of junk sitting on my desk. No color correction – this is resized straight out of the camera.

Built-in flash:

Bounce flash:

The difference is that the light-emitting part of a bounce flash can rotate up, so instead of light traveling straight to the subject and creating a harsh glare, it bounces off the ceiling and looks like natural, diffuse sunlight.

This past weekend (not this weekend – I’m behind on my blogging) was the first (virtual) sitting of MIT’s Freshman Essay Evaluation (FEE). I, always a clever guy, took the test this session, the same weekend as my high school graduation and half a dozen graduation parties.

The pinnacle of my tooling was certainly outlining one of the essays in a notebook on Sunday evening while eating at Papa Vino’s following graduation. That restaurant is one of a chain featuring overpriced, undersized portions of Italian food, but it’s tasty, if a bit tame. For appetizers, you pour olive oil over toasted garlic and you can dip chunks of bread in it, soaking up the flavors and unsaturated fatty acids. While enjoying the garlicky goodness, I was doing all sorts of prewriting for one of my essays, in the process dripping olive oil all over the page. I was writing in a National Brand “computation notebook,” a bound stack of solid graph paper, which soaked up the oil, but didn’t transfer it onto any other pages. I got this at Caltech’s bookstore as it was going out of business at PFW, and I approve of it (incidentally, it seems to be the same notebook used in 8.13, though I’m quite certain they don’t cost $40 – I plan to get several for note-taking).

That third sentence sentence in that last paragraph was a little off, actually. I’m pretty sure it implies that you soak up the flavors and unsaturated fatty acids, rather than the bread, but I suppose it’s technically correct anyway. Speaking of the hazards of technically correct things, I’ll be fortunate if my FEE-grader doesn’t fail me for this gross overuse of the semicolon. It would be appropriate: live by the semicolon, die by the semicolon.

“A comprehensive solution to this problem should benefit the public, both as consumers demanding more individualized medical care and as patients who benefit from well-informed doctors equipped with valid scientific studies; it should inform consumers about the limitations and abilities of present-day genetic testing; it should come at a reasonable cost to already-burdened government agencies; it should encourage accurate, cost-efficient testing firms; it should preserve consumer choice and privacy; and, it should drive innovation in genetic testing and in scientific research.”

Yea, that’s one sentence with five semicolons. Now, I’m actually not sure how much I’m allowed to talk about the FEE, though it’s all finished now, so I won’t talk about the test itself or the readings or essays. Instead, I’ll give you a little tour of where and how I write.

1. An FEE reading. It might be top secret, so I won’t say what.
2. The sweet notebook I mentioned, filled with prewriting. It pwns hardcore.
3. Staedtler leadholder. I’m extraordinarily easy to distract when writing, so no eraser and no clicky. I got rid of the clip a long time ago, so it’s just a way to hold graphite – nothing more. That’s what I need.
4. Strunk and White. It’s not a consistent, unified approach to style, but it’s decent. It’s not too useful as a reference, but I carry it everywhere when I’m not writing but not at my desk typing. I pull it out when I have free time and just get in the zone.
5. Slinky. I allow myself just one distraction to keep things simple. Often, I’ll lay it across my desk and set up standing waves, then see how many overtones I can manage. Usually three.
6. Speakers (Bose). Free (woot for family that overestimates audio system needs!). For writing, I like minimalist music. John Adams is probably my favorite. I wrote the FEE essays to his Harmonielehre, Naive and Sentimental Music, and Shaker Loops. Also good is Philip Glass. Some of his is really minimal.
7. Monitor. I heart this one. I used an ancient Dell CRT until it failed. Now, 24″ WUXVGA. I heart it. It’s wide enough that I keep two Chrome screens open at a time. Hooray, productivity!
8. Window. I keep one open most all the time, but especially when writing. I don’t find cars, lawn mowers, or birds distracting. Just the opposite.
9. Keyboard. Yea, I was grasping for items. I keep NumLock on at all times so I can use the numeric pad. That’s right, it’s not very interesting – just a half-decade-old keyboard.

I’m not sure how much I missed. I’ll try to update later if I think of something. In the meantime, I’ve got a to-do list with 12 items, 3 of which are completed. I should have done FPOP application today, but didn’t. And I’ve got about six blog entries that I want to write, but no time to actually type them. My to-do list has 12 items and three checkmarks. Rawr.

Of all the numerous documents bestowed upon prefrosh checking in for Campus Preview Weekend, none is more important than the CPW booklet, a 96-page tome emblazoned “MIT CPW” in bright tangerine and maroon block type.  Far from decorational, the gaudy colors make this softcover the ideal test for prefrosh identification – more useful than phenolphtalein or even the flame test.

No CPW-goer would set out for a day’s adventures without the booklet as it contains, in addition to useful maps of campus and the Cambridge area, the dates, times, locations, and descriptions for all 620 officially-recognized CPW events.  That’s enough for one to begin every 7 minutes or – more closely resembling reality – for 8 to begin on every hour of the weekend, causing even the most fervent Course 8 disciples to curse the physical laws restricting them to a single location at a given time.  Of course, the most hardcore physics geeks attempt to channel the powers of quantum mechanics to transform themselves into distributed probability waves, but are ultimately unsuccessful and, along with their fellow mortals, only get to attend a fraction of the events they would like.

These events are the most visible external feature of CPW: they are many, well attended, and thoroughly documented.  However, I’m writing here to point out another aspect of CPW, one far less frequently discussed, possibly because of the challenge describing it poses.  It is the difference of CPW and the events; it is why years of blog posts detailing the minutae of CPW never adequately described the vitality and excitement of the weekend; it is the intangible  element that makes CPW so much more than a jumble of activities.

Most of all, it is extremely difficult to define.  So, I’ll instead attempt to demonstrate the part of MIT that can’t be found in any booklet: the other CPW.

Thursday, 8:15-9:15pm Frialator @ Theta Xi
After wandering Boston lost for the better part of an hour, our group was getting quite hungry, so we decided to head to one of the fraternity cookouts on Beacon Street. Under the direction of our dubiously-appointed navigator, Maria ’13, we located a frat house and knocked at its door. As it turned out, it was a Boston University fraternity and was understandably not holding a CPW barbecue.

Further roaming brought us to Theta Xi, an MIT fraternity whose Thursday-evening cookout was long over, but which nonetheless invited us to pick through the leftovers.  To our surprise and delight, among the lukewarm hamburger patties and scattered ketchup bottles was a large cardboard box filled with industrial quantities of frozen french fries.  The brothers of Theta Xi saw our excitement and offered to prepare some for us.  We followed downstairs to the kitchen, where we saw the most glorious thing a disheveled pack of hungry prefrosh could imagine: a piping-hot frialator.

The master chefs of Theta Xi fried and salted an entire bag of potato sticks, far more than we could possibly eat. Then, we all headed back upstairs to the TV room, where the Daily Show with Jon Stewart was on, shortly followed by the Colbert Report. Jon talked about the tea party protests, teabagging (of course), and the Red Sox / Yankees rivalry, all of which collectively made for some amusing but thoroughly intellectual commercial conversations.

The brothers also gave us a tour of the roof deck, a delightfully hazardous structure grandfathered into local ordinances.  In addition to making a fine grilling platform, it has an excellent view of the imfamous Citgo sign.

Thursday, 9:30pm Course 5 UROP Seminar @ Boston West Saferide
Walking the Harvard Bridge and counting off smoots along the way is an excellent CPW activity, but the novelty wears off quickly after the first crossing, so we literally chased down the Boston West Saferide for the trip back to MIT.

On the mostly-empty bus, we were easily recognized as prefrosh by a friendly Course 5 senior. During the ride around Boston, we talked about his experiences at MIT, focusing on research at MIT and in Israel through MISTI. The discussion quickly involved everyone riding on the bus, and Divya ’13 led nearly half a dozen other prefrosh in an “OMG, you’re from New York too?!” powwow.

Once back on campus, we wandered the floors of Burton-Conner (all of them) and settled into Conner 2′s TV lounge for the night, just down the hall from where I was supposed to be sleeping in suite 223. From about midnight to 4am, there was a steady stream of floor residents walking down the hallway, most of whom spotted the prefrosh in the lounge and stayed to chat. A constantly-revolving set of natives sat with us on the couches, and we talked about everything from 8.01 flavors to dining (which is still an extremely touchy issue) to Mason’s knack for awkwardly and hilariously ending conversations, something he had done 117 times since the floor began keeping tally on a whiteboard in the lounge.

Around 4 am, we and the more permanent inhabitants of Conner 2 went to sleep.  The plan was to sleep until lunchtime, then carry on well-rested, but a bright East Coast sunrise at 6am got us up in time for earliest of waffle breakfasts.   Apparently, even our celestial friend knows: if you’re sleeping at CPW, you’re doing it wrong.

Friday, 7:30pm Divya ’13′s Birthday Party @ BTB Lounge
Friday morning, I attended a 2.007 (robot-building) lab at the recommendation of a dedicated mechanical engineering student I met Thursday evening walking down the Infinite Corridor. She was walking down the center of the hallway working on a Solidworks model on her laptop, but apparently had time to chat with prefrosh about Course 2. Shortly thereafter, I attended an 8.022 (“electromagnetism for masochists”) lecture, wearing my Maxwell’s equations t-shirt, which received a passing compliment from the lecturer as I took a seat.

The next few hours blurred, but I’m fairly certain I toured East Campus in that period. Next thing I remember, I was at Meet the Bloggers, which as an “event” would be outside the scope of this post, but there Yan presented me with another Maxwell’s equations shirt, but this one from Course 8, so the equations were written in proper symmetrical differential form. At one point that evening, I was simultaneously wearing two t-shirts bearing Maxwell’s equations, one in integral form and the other in differential. That’s a level of nerdiness frowned upon even at CPW.

After Meet the Bloggers, which ran late, a text message proclamation arrived from Divya ’13: “I HAVE CAKE!!!”  The promise of food assembled the previous night’s wandering group within minutes.  As it were, Divya’s parents drove 7 hours round-trip to deliver this wonderful cake (only slightly damaged) for her birthday.

Requiring a table and utensils, we headed back to Burton-Conner and this time settled on Burton Third, home of the Burton Third Bombers. Sitting in the lounge, we ate as much as we could (perhaps one third of the cake) and talked with some of the floor inhabitants. We offered them some of our surplus cake, but they politely declined, typical of BTB’s bashful reputation. When we had finished, however, we left the cake for the floor residents, and when we checked back in a few hours, it was devoured.

Friday, 10pm-2:30am Absolutely Nothing at All @ Anywhere
Nothing of any interest whatsoever to anyone happened Friday at 10pm. This stretch of nothingness ran well into the wee hours of the morning.

Afterwards, we groggily stumbled back to some lounge on a Burton floor with abundant couches, still contemplating the inky black void encompassing the last 5 hours of our CPW experience. Sleep arrived at about 4am.

Saturday, 4-4:30pm Impromptu Rock Band @ Conner 2
Another day’s worth of drifting around campus and event-going somehow led us to Conner 2, where I was theoretically staying. I hadn’t seen much of my host due to my wandering, but he gave us a tour of the floor and then demonstrated his drumming prowess on Rock Band. Here, Snively ’11 on drum set, Laura ’13 on bass, Albert ’13 (barely visible behind Laura ’13) on vocals, and Chris ’13 (off-screen) on guitar play an unknown song in the TV lounge of English House (you can even see the Union Jack on the side wall).

Saturday, 9-10pm Getting Lost @ Boston
That evening, when hunger pains returned, we flipped through our CPW booklets, scrounging for food-containing events. Promising looked Sigma Nu’s “Pizza/Smoothies/Video Games!!” as it apparently involved pizza, smoothies, and video games, along with a second exclamation mark promising copious amounts of excitement.

So, we once again crossed the river, then sat under a street light for several minutes trying to locate Sigma Nu’s dot on the CPW booklet map. No, I jest. We kept walking without direction, eventually boarding a Saferide. The friendly driver let us off at the next stop, saying the bus didn’t get any closer, and pointed us up a hill. Being clever prefrosh, we recognized the hill as a freeway exit ramp and instead veered to the side. Through a long and exciting series of misadventures, we found ourselves at Fenway Park (game night, Red Sox v. Orioles).

Trust me when I say this was among the most enjoyable lost experiences I’ve ever had, but we were all still hungry, so we oriented ourselves and headed to Sigma Nu, 28 The Fenway, which is interestingly enough nowhere near Fenway Park.

Saturday, 10pm Pool and Photography Seminar @ Sigma Nu
Finally, we arrived at Sigma Nu, which is a fascinating fraternity. It is geographically isolated from most of the frats, which are largely on Beacon and Bay State Road. The house is actually more accurately described as a mansion, with grand dining halls and a massive 4-story spiral grand staircase, capped off with a stained glass roof.

When we arrived, the smoothies and video games were well underway, but the pizza had been reduced to meager scraps of Hawaiian. We grabbed the remainder and toured around the building, ending up in the basement, where we played pool and talked to the brothers of SN for several hours. We also attended a brief photography masterclass, which presumably inspired Divya ’13 to create this masterpiece.

Sunday, 3-5am Chair Racing @ The Tunnels
If there’s one thing that no CPW experience would be complete without – and there is one – it is pulling an all-nighter. For me, that was the last night of the weekend. After departing from SN and walking across the Harvard Bridge in the rain (the Weather Machine broke the last day), we headed back to the Infinite Corridor.

More specifically, we headed under the Infinite Corridor, into the tunnels. These passageways are useful for traveling in the cold Boston winters, but in a few locations, then also slope steadily downward. A resourceful student could locate rolling chairs and head to one of these inclines. A lucky prefrosh, such as a blurry Maria ’13 here, could walk down a tunnel, turn a corner, and find herself in mortal peril.

Of course, even more dangerous than walking through tunnels filled with speeding chairs is to ride said chairs down the treacherous slopes, so that’s precisely what we did for the following hours. Several bruises, scrapes, and one narrowly-avoided cranial fracture later, we left the underground to watch the Sun rise over the Boston skyline, all without a minute of sleep.

If there exists an appropriate conclusion to a CPW entry, it’s not something I’m capable of writing, so in its stead, I welcome the Class of 2013 and wish all future applicants good luck. Having just turned in my enrollment forms, hopefully I’ll see you all at another incredible CPW.

Update, May 3, 2009:
Posted on the MIT Admissions Blogs.

A little over four hours ago, Steven Swanson and Richard Arnold of STS-119 finished deploying the fourth bank of solar panels on the S6 truss of the International Space Station, pushing the ISS past Venus in apparent magnitude and making it the second-brightest object in the sky.

The ISS has long been a visible object in the night sky, but it is now easily observable by even untrained observers. You can easily track the ISS yourself and find flyover times, which occur frequently. The greatest challenge in seeing the ISS is clouds.

Using that same site, I found out that the ISS would fly past my home at around 10:09 PM. I, of course, went out to see it.

The streak in the lower right is the ISS, passing at about 10 degrees elevation. The lights in the lower left are Chicago. Naturally, it was dark (well after twilight, 37% moon), so this exposure is somewhere between 30 and 90 seconds. I took over a dozen of these in different permutations, so with temperatures just below freezing and a brisk wind, I was getting quite chilly. So, I ran around in circles, hunched over, counting seconds off my exposure. I made quite a nice little track.

I think I worried some of the homeowners on the beach. I probably looked quite dubious running around in little circles on the beach well after dusk. Anyway, this made for an enjoyable evening. I’m going to get some sleep, leaving you with only a single request: take a moment to remember our late friend, the Spacebat.