How to use public PCs safely with Linux

How to use public PCs safely with Linux

Summary: Public PCs aren't safe, so what's a PC user to do? Carry a Linux distribution on a USB stick in their backpocket of course!


I've always been wary of "public" PCs in hotel business centers and libraries. It turns out I had reason. The Secret Service recently discovered that hackers are using keylogger Windows malware to steal your personal data.

If you, as I do, often use public PCs to print out boarding passes for return business flights, this is bad news. I've had airlines ask me for not only my frequent flyer membership ID, but for my name, address, phone number, and, oh yes, my credit card number.

Live Linux distributions can help. As security expert, and my colleague, Larry Seltzer pointed out, the one way you can be sure you're safe from any virus on a PC is to boot it off CD or USB key with an operating system image you control and trust.

Seltzer, while acknowledging that there are many live Linux distributions, doesn't think Linux would be practical for most people. Instead, he recommends Windows to Go, a version of Windows 8 that's available only to Windows volume license owners.

I disagree. You don't have to know Linux at all to use a live Linux USB stick, CD or DVD for the tasks you're likely to be doing on a public PC. These jobs include, printing tickets, checking an address, reviewing your schedule, and reading e-mail. In short, for most these chores all you really need is a web browser.

Trust me, if you can run a web browser on Windows, you can run one on Linux. 

For this tutorial, I'm going to presume you're a Windows user. The techniques I describe, however, will also work for Mac and Linux users.

The only real work you need to do to run Linux off a CD, DVD, or USB stick is to place the distribution on the boot-media in the first place. I recommend making both a USB key drive and a CD/DVD Linux boot disc. That's because there are still a few older PCs out there that won't boot from USB sticks.

The first thing you need to do is to download a live Linux distribution. You can find a comprehensive list of such distributions on the LiveCD List. Really, though, almost all desktop Linux distros come ready to run in live mode.

Once you select a distribution and download it, you'll have an ISO file. This is a special file type that you must "burn" to a CD or DVD. You simple can't copy it to a blank disk. If you do, you'll just end up with an unusable disc.

To burn an ISO, you need a CD/DVD burner program that can handle ISOs. Many programs can do this, but if you don't alreadyhave one you use, I recommend a freeware program like ImgBurn, or PowerISO 6.0, a full-featured commercial program that costs $29.95.

Once you have a burning program in hand, you use it to burn the ISO image to your disc. After that's done, use the program to check your newly burned disc for errors. Over the years, I've found that more problems that happen when running Linux from live CDs come from bad media than all other causes combined.

Putting Linux on a USB stick also requires you to download an ISO. But instead of using a disc-burning program, you must use a specialized program to "burn" the ISO to a USB stick.



I recommend one of two programs for this: LinuxLiveUSB, or UnetBootin (which works on Linux, Mac, and Windows). Both are freeware. Both are simple to use but of the pair, LinuxLiveUSB is easier.

With each, you simply pick the distribution you want to install, tell it where to find the ISO, whether you want to make the USB stick "live," then tell it where to install the distribution.

The one thing you should be careful about at this final stage is that you must make darn sure you're installing the Linux distribution to your USB stick. After all, you really don't want to install Linux on top of what was once your music collection on a USB hard-drive!

The only real decision you need to make is whether to make the USB stick "live" or not. In this context, "live" means that you can not only run Linux from the stick, but you can also save settings, install programs, and keep new files on the USB stick itself. Since you may need to install printer drivers to work with the hotel's printers, I recommend making the drive "live" with a few hundred MegaBytes of space. 

Once you have your disc or USB, stick it in the PC and reboot. The machine should then start running Linux. If it boots instead to Windows, you may need to tell the PC's BIOS or UEFI to boot from the disc or stick. Unfortunately, BIOS and UEFI vary wildly on how you invoke them.

To reach the BIOS or UEFI, reboot the computer and look for a brief message as it starts up that will tell which keys or keys you need to press to get to the BIOS/UEFI. Commonly, these involve one of the function keys, the Esc, or Delete key. Once you have this worked out, you'll end up in a menu interface. From here, tell your system that you want it to boot from your optical drive or USB stick instead of the hard drive.

Once, it's up and running, all you should have to do is to bring up the web browser. On Linux, this is almost always Firefox.

Once you have a web browser up, I think you'll know what to do! Have fun, find the direction to the stadium, check your e-mail, print out your tickets, and know that you're doing all this in the close-to-perfect security of Linux.

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Topics: Enterprise Software, Linux, PCs

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  • Windows boots faster

    Most Linux distros take damn near forever to boot up... so while live boot works rather well on them, I don't usually have time to wait for them. I keep stick versions of Windows 8, Puppy Linux, and used to ferry about Knoppix; but honestly, don't usually have time to wait.

    Android x86 is pretty zippy to boot, but power manages like crazy (distracting on a PC.)

    Mostly though I just have a laptop. Seems easier. :)
    • ?

      I have several VMs on my home system. Here are their boot times.

      Windows XP -- 29 seconds
      Windows 7 -- 31 seconds
      Windows 8.1 Update -- 26 seconds*
      Peppermint 4 -- 24 seconds
      Crunchbang 11 -- 13 seconds
      Elementary Luna -- 14 seconds

      Linux SERVERS may boot slowly because of the self-test and setup they need to do. Likewise, Linux clients doing a lot of pre-login prep. But in my experience Linux boots much faster than Windows, even than Windows 8.x.

      * My Windows 8.1 Update VM boots slowly because it doesn't hybernate/revive. It does a full shutdown and startup. It's a bit faster than XP and 7, but only a bit.
      • Yup - linux boot super fast.

        It was all the rage about 5-6 years ago with most popular distros trying to get their boot times down. For conparison just fire up a BSD - when I started out that's how long a boot took!

        Even a full on Open suse or Ubuntu install boots very sharpish.

        As for this article, it's a bit old hat isn't it? I mean I was making bootable usb's back in '08. We don't need squash fs usb sticks now - just install your linux TO the stick and run it from there. Squashfs and persistence folders have horrific performance. You'll also want some pretty sharpish memory chips in your stick.

        Puppy might be a way to go if you do want a live install because it will get to ram nice and quick. I always have a puppy install on my drive just for booting to ram.

        However all of this MUST be moot. 2 jobs back we had 'public' PC's in the lobby of our building, and gues what? Just like every job I've had usb booting is disabled and the firmware is password locked. That's pretty much IT intern security right there. I'm struggling to imagine these public PC's that let you just boot up a USB stick OS?

        If simple security measures like this aren't being taken, don't even stick your USB in it!
    • Not true

      > "Most Linux distros take damn near forever to boot up... "

      Fond of hyperbole?

      Modern distros generally boot as fast as or faster than Windows 8 even when it has Fast Startup enabled, which is ironic since Fast Startup isn't even a real full boot, but a hybrid resume from hibernation. I've got plenty of external drives with different OS's on them and the modern distros using upstart (Ubuntu and friends) or systemd typically boot in about 10 seconds. In my experience Linux Mint is even faster with sub-ten second boots. Distros still using the older SysV init are much slower.
    • Boot Times are not of Primary importance....

      What matters most is the actual performance of the operating system once it has booted be it Windows, OS X or Linux.
      Furthermore depending on how much RAM etc. you have allocated to the virtual machines you may not be observing accurate readings. In virtual environments even when the RAM etc. are ramped right up it is inevitable there will be some drop off in performance unless you are working with quality virtualisation software such as Parallels Desktop 9 in my case running Windows 8.1 Update 1 inside OS X Mavericks. Performance is almost as good as a physical machine, mind you that is with the following allocated 4GB RAM, 4CPU's and 512MB Graphics.

      Machine is a 21.5" 2011 iMac with 8GB RAM, Intel i5 2.5GHz Sandy Bridge Quad Core CPU and AMD Radeon HD 6750M 512MB Graphics.
      • Forgot to add....

        Buffalo Mini Station Thunderbolt external SSD Drive which I run the whole system from (including OS X Mavericks)
    • Forever to boot up? Well, not really -

      USB based Linux is fairly quick, though it's been a while since I tried one.

      The real hassle is creating a USB stick with bootable Linux. Seems easy to those of us that use computers daily and like getting into the guts of the system, but, for the average user? probably not.

      It's a workable solution for less than 1% of the population with the knowlege to build the stick and the willingness to plug it in and reboot.

      And if the owner of the public computer had a brain, they'd disable the USB ports at the BIOS level anyway to keep people from hacking the system with USB sticks with and OS anyway.

      Sounds so simple and complete, but in reality it's very limited.
  • Two additional items

    In some cases, the keylogger could be hardware-based. If so, then the keyboard attached to the public PC could be used to collect one's online authentication parameters. To thwart hardware-based keyloggers, I'd use one or both of the following:

    o virtual keyboard, preferably with random elements
    o password manager

    This way, it will be unnecessary to type in one's authentication parameters.
    Rabid Howler Monkey
  • How to use public PCs safely with Linux

    Wow, how low can linux users go? This article shows us. Not to be outdone by his colleague because he didn't use linux, SJVN has to write his own article about the subject. Very low dude.

    I would never trust linux on a private, public, or usb key. The average user isn't going to know to download the source code and compile it to run their apps. And knowing that the telnet port is open on linux would open up any public PC to a world of crime. In fact you would be in worse shape if you were to boot into linux on a public PC than if you just used the already installed Microsoft Windows. Microsoft Windows offers a fine grain of control over the user accounts and files. It would be a terrible experience for the user not just because of linux's lack of security but its lack of media options as well. If the user wants to buy last minute tickets and its a flash site they won't be able to because flash is unstable and always crashes on linux. They would have no way to repair it.

    Using linux is the absolute worst thing you can do in this situation.
    • Re: Not to be outdone by his colleague?....

      Oh come on LD. If its Microsoft related you sit up and take note. If its Linux related you slap it in the face. SJVN as with many of his articles of late are both interesting and engaging.

      There are safer ways to use public computers such as Linux USB or even LiveCD providing as with other platforms all security updates are applied. Although from Windows 8 onwards it is more secure it still scores behind Linux and OS X.
    • Get some new material man.

      For those who didn't know, open a terminal and type cd /etc/xinet.d, then nano telnet (or whichever editor you use) and you'll notice there is a line which reads:
      disable = yes

      That is the default on linux for years now, even if you're a nut and built your own Arch system like I did, it's the same way, that's just lame of you, LD.
      • Whoops!

        It was xinetd.d, I'm so used to tab completion I got lazy.
    • Great jokes, LD!

      I'm so happy that we have you as a comedian in here, to balance out the serious posts.

      Please write some NEW Linux jokes too (not only the ones about compiling and Telnet).
    • What kind of "IT Professional" are you?

      Occasionally you have claimed to be an "IT Professional", yet you persistently demonstrate that you have no clue what the telnet port or compiling is. I could train a parrot to say "telnet port" and "compiling" and that bird would comprehend those terms more than you do.

      So, Loverock., what is your profession in IT? The only place in IT I could see somebody like you holding down a job is on the sales floor at Best Buy. If I am wrong, state clearly what you actually do in the IT world, other than fill the forums on zndet with effluvium.

      Your posts are actually an embarrassment to Microsoft. Maybe that's your plan. Actually you are working in Cupertino, not Redmond.
    • Over the years... have gone from silly to a plain liar.
    • Using linux is the absolute worst thing you can do in this situation.?

      What Rock have you been hiding under?
    • What?

      This is a joke right? Cause you obviously done have a clue what you are talking about. I mean not a clue.
      • edit

        edit: don't have a clue.
    • Still at it

      Thought I come back and see what has changed. Same arguments, different handles. Loverock any OS at this point is better than Windows 8. Windows 7 jobber for those that do not want to jump ship. To secure Windows, you pretty much have to turn off all necessary services, run Firefox, don't install flash run adblock and it becomes less functional to use. Might as well go with Linux Mint 17 LTS since all the malware is directed at Windows. Don't forget adblock. Make sure you write your own punishing filters to avoid being tracked all over the place regardless of OS.

      My live CDs are burned to a SD card that is write protected that is used in a USB to SD card adapter. This allows 15 second boots from post to the password prompt. The program to burn the ISO to a flash drive is Pen Drive Linux or universal-USB-installer- being the most current. I find that is the easiest to use when using Windows. 8GB SD Cards can be had for $10.
  • Thanks, Mr. Davidson, for the worst advice ever given on ZDNet

    "you would be in worse shape if you were to boot into linux on a public PC than if you just used the already installed Microsoft Windows"

    Dear readers, Mr. Davidson is ZDNet's class clown. Please laugh and/or applaud, but don't take his so-called advice.
    Rabid Howler Monkey