Netbook screen resolution

I love my Dell Mini 9.

I'm back from UDS in Orlando, and have once again spent a whole week on my Mini 9. It's got a webcam so I can call home, and has bluetooth so I can use an external mouse without plugging in a dongle when the need arises. Although I've tried netbooks with 92% keyboards, I'm not ready to sacrifice portability by adding the extra 2 inches required to fit them. The keyboard on the Mini 9 has the perfect feel for such a small keyboard, and I've gotten quite used to it.

The only thing I can't quite get used to is the native screen resolution: 1024x600 is not a lot of screen real estate to work with.

The other day I was looking at the xrandr documentation, and I noticed it supports screen scaling. I now regularly use the following command:

xrandr --output LVDS1 --scale 1.25x1.25

This scales my 1024x600 netbook screen to 1280x750, which is really cool when trying to view large web pages, or any other application that uses a lot of screen space. The downside of this is a slight blurriness that is, in my opinion, an acceptable trade-off.

Unfortunately it doesn't look like there's a way to set scaling in the GNOME Monitor Preferences tool.

Stuck on dial-up (Updated)

My mother has been a happy Ubuntu user ever since I installed Dapper to solve the countless problems she was having with Windows Me. Since her computer is starting to age, and she's a 5-hour drive away, I bought her a brand new computer for her birthday, which I've been installing with Lucid this week.

Problem is, she is still stuck on Dial-Up internet access no matter how hard she's tried to get broadband from the local phone and cable companies.

Unfortunately, NetworkManager still doesn't have 56K modem support, so a few steps are necessary to setup Ubuntu for dial-up.

Since her phone line is noisy, I purchased a reliable modem that doesn't need special drivers to work in Linux, along with an appropriate USB-to-serial adaptor.

Once I made sure the modem was visible by searching through dmesg for the right serial port, and testing it with minicom, I performed the following steps:

1. Installed the gnome-ppp package
2. Added her user to the "dip" group so gnome-ppp could spawn the pppd daemon
3. Configured gnome-ppp with the phone number, username and password provided by her ISP

Once that was done, connecting to the Internet worked great, except for a single problem: Firefox would always start up in "Work Offline" mode. It turns out Firefox uses NetworkManager to figure out if an Internet connection is available when it starts. To fix this:

1. Type "about:config" in the Firefox URL bar
2. Search for the "toolkit.networkmanager.disable" key
3. Switch it to "true"

I'm looking forward to seeing her go from Hardy to Lucid this weekend!

Updated 2010-10-22:

So, I ran into a couple of extra difficulties when I actually installed her new computer. It seems her ISP uses CHAP or PAP to authenticate which wasn't the case when I tried connecting with my ISP at home. Gnome-PPP uses WvDial to perform the actual dialing, and WvDial tries to add the necessary authentication information itself to the /etc/ppp/pap-secrets and /etc/ppp/chap-secrets files. Problem is, those files are owned by root and are 600 by default. The pppd man page states "this file should be owned by root and not readable or writable by any other user. Pppd will log a warning if this is not the case.", so this isn't an easy problem to solve. Since I didn't want her running gnome-ppp as root, I changed both files' ownership to root:dip and permissions to 660. This allowed gnome-ppp to authenticate to her ISP, even though pppd is logging a warning.

The second problem I encountered was that Evolution would always come up as offline. Like Firefox, it integrates with NetworkManager to check if the computer is online. Unfortunately, unlike Firefox, Evolution doesn't seem to have a way to disable NetworkManager integration. Since time was limited, and I knew she wouldn't be using the Ethernet port on her computer, I simply disabled NetworkManager entirely by editing the /etc/init/network-manager.conf file.

My stepfather owns a Dell Vostro laptop with Lucid on it, and uses it to connect to the high-speed wireless network at work. He asked me if I could get a modem for his laptop so he could use Dial-Up when at home. I'm not sure how I will be able to handle this for now, as disabling NetworkManager won't be an option in his case...

New GPG key!

In accordance to the Ubuntu Security team's GPG key transition plans, I now have a new GPG key capable of generating SHA-2 signatures.

If you've signed my old key (40B8CCDA) in the past, I would appreciate it if you could take a look at my transition statement, and sign my new key (A744BE93).

Thanks!

Trying to switch to Empathy

I try to dogfood as much as possible. I try to use the actual applications Ubuntu ships by default for everyday things like web browsing, email and IM. I believe this is the best way for applications to get tested properly, fixed, and improved. If developers don't use the default applications because they are buggy, or don't contain necessary features, how can we expect them to be appropriate for regular users?

I've been a Pidgin user for years. It's a great, but now there's a new kid in town: Empathy, which is now the default IM client installed in Ubuntu and other distros. This week, I am attempting to switch from Pidgin to Empathy. So far so good. It's working pretty great, except for one thing: I keep missing the notifications when people send me messages.

If I already have a chat window open with someone in Empathy, and the person sends me a new message, I get notified in three ways: I get a temporary notify-osd message, the Indicator Applet envelope turns green, and the window in my window list flashes for a few seconds and stays highlighted and bold.

Most of the time, I miss the notify-osd popup, as I'm typing something, and tend to always finish before looking up at the alert. Once I do, I rarely have time to read the whole thing before it disappears. My Indicator Applet envelope is green most of the day as I almost always have unread messages in my Inbox. But as soon as I finish the task I'm doing and go to switch windows with the window list, I notice the highlighted and bold window demanding attention.

The problem I have with Empathy is there is no way to tell it to open a new chat window automatically when a new message arrives and there isn't already a chat window open. When that happens, I don't have the highlighted window in the window list demanding attention, and often discover that I missed an IM an hour later when clicking on the green envelope to read my email.

What am I doing wrong?

Canadian tax software and Linux

Well, it's tax time again!

This used to be the part of the year I would dread. Not because I feared how much income tax I would need to pay, but because I knew I would have to get Windows running in a VM or on a spare computer in order to use tax preparation software.

I would get heartburn from wondering if the new flavour-of-the-day copy-protection mechanism the software used would actually work in a VM, and if it would let me open up my files again after reinstalling it if something went wrong. Top that off with the fact that trusting your important data to Windows is like locking your safe with duct tape, and I'd be popping Rolaids like candy.

Are all the security updates installed?
Every time I open "Windows update", it manages to find some more.

Is my antivirus software properly installed and working?
What if I got malware while purchasing the antivirus software online, before I installed it? Which one do I choose?

Oh great, the new version of the tax software uses Internet Explorer to update itself.

Luckily, a couple of years ago I discovered UFile.ca, a web-based tax preparation application. They even officially support Linux! It's quite refreshing to see a Tux logo right next to the Windows and Mac logos. It's even easier to use than the software I was previously purchasing!

Of course, it's web-based, so it's up to you to decide if you're willing to accept handing over your tax information to a third party. In my case, the decision was easy: I get to decide who can see my tax information, which is a lot better than hoping no one could see it.

Goodbye heartburn!

Ubuntu movie sighting

I was watching the Millenium movie last night, and spotted an Ubuntu desktop being used by the "Plague" character:

GNOME Keyring

For the past week or so, people have been talking about a “security issue” in Seahorse. This sums up my opinion on the matter:

This isn't a security issue, and there is no good way to fix it.

There, I've said it. Now, here's some background:

Although people are talking about Seahorse, the actual application that manages passwords is called GNOME Keyring. GNOME Keyring is an application that manages a user's authentication information, such as user names and passwords. It stores the authentication information in one or more encrypted databases, called keyrings. A password, supplied by the user, is required to unlock a keyring, at which point all the information contained within is decrypted and is made available to applications via the libgnome-keyring library. It is similar to the Keychain in Mac OS X, and Protected Storage in Microsoft Windows.

Traditionally, a desktop application that needed to remember a user's password, such as an email or an instant messaging program, would store the password in a hidden config file in the user's home directory. Appropriate permissions would be set on the file to make sure other local users can't read it.

Sometimes, passwords stored in this manner would be obfuscated using a reversible scheme, as the password needs to be converted back to plain text in order to be used. This would provide a false sense of security. Users inspecting the file would think the passwords were encrypted, but a myriad of little recovery scripts and on-line converters were available to anyone who knows how to perform a Google search.

A password managing daemon, such as GNOME Keyring, increases the security of stored passwords for the following reasons:

• Passwords are stored in a database that uses real encryption, not just an obfuscation scheme
• A single code base needs to be audited to make sure no vulnerabilities exist in the encryption algorithms that are being used
• The database is protected by a password that is known only to the user who unlocks it
• Since the database is encrypted, no other user or bootable CD can recover the stored passwords if the unlock password is not known

So, if GNOME Keyring increases the security of user credentials, why can you see your passwords exposed in plain text when you open Seahorse? Because you've unlocked the keyring using your login password.

Although GNOME Keyring supports multiple keyrings, there is only one by default, called “login”. This keyring is automatically unlocked by a PAM module when logging into a GNOME desktop. When the desktop session is closed, the keyring is locked. When the keyring is in an “unlocked” state, the database files are decrypted using the decryption password and all the contents are in memory for gnome-keyring-daemon to access.

Now, the attack scenario that has been talked about this past week has been leaving your computer unattended, and an attacker using Seahorse to access your clear text passwords. This has been criticized as being a security issue, and a few “solutions” have been suggested to “fix” the issue. Here are some of the scenarios proposed:

Scenario 1: Ask for the user's password before displaying the clear text keyring contents.

This scenario doesn't work in practice. Once the keyring is unlocked, the contents are available under the user's security context. Since the GNOME Keyring daemon is under the user's security context, the intruder has every privilege necessary to simply bypass the authentication step and directly read the unencrypted keyring from memory. Even if Seahorse asked for a user password, nothing could prevent the intruder from simply downloading a “reveal passwords” application from the Internet or a USB key. There is no difference in time or skill required to open Seahorse and display passwords, or to type “gnome password revealer” in Google and execute the first application available for download. The GNOME Keyring project has a web page to explain this.

Even worse, the fact that a password would be required in Seahorse would make the user think that a password is required to see the clear text information. This would give the user a false sense of security. If Seahorse asks for a password, but a five line python script can bypass the password, bug reports would change from “Seahorse displays clear text passwords” to “Seahorse authentication can be easily bypassed”. This scenario doesn't solve the problem.

Scenario 2: Make keyring session expire automatically after a certain time.

If the keyring session expires automatically, such as every 15 minutes, it becomes useless. The purpose of the keyring is to store passwords that are needed by applications. With keyring session expiration, Evolution can't automatically check for new mail, Empathy can't auto-reconnect to instant messaging networks, the wireless connection can't re-authenticate to access points.

If you expire the keyring session every 15 minutes, you will probably need to type in your password every 15 minutes. Besides, if you leave your computer unattended, 15 minutes is long enough for an intruder to steal your passwords. This scenario doesn't solve the problem.

Scenario 3: Make the keyring daemon run as root or as a dedicated user.

The idea behind this is to have a central daemon that would authenticate users and applications before giving out passwords. Since the daemon doesn't run under the user's security context, no amount of hacking by an intruder in an unlocked desktop session would result in gaining access to the unlocked password database.

Although this scenario may seem appealing, it would probably be less secure than the current approach. If we have a central daemon that serves all users, a programming vulnerability could result in other users gaining access to your confidential information. Besides, if your desktop applications, under your security context, can gain access to the passwords they need, so can an intruder in your security context. The intruder's script can simply spoof the desktop applications themselves to get the passwords, or get them out of the application's memory. This scenario doesn't solve the problem.

Scenario 4: Stop using GNOME Keyring.

Well, GNOME Keyring was created to solve the problem of people writing down their passwords everywhere, including text files or their computer, and the problem of applications storing passwords in text files. Removing GNOME Keyring would decrease security to the state it was before. This scenario doesn't solve the problem.

Scenario 5: Locking the desktop session when stepping away from the keyboard.

Now we're getting somewhere!

Since the attack vector that's being discussed is an intruder gaining physical access to an unlocked desktop, the simplest way to prevent this from happening is to lock the desktop when you leave it unattended.

If someone gains access to your desktop, your passwords are not the only thing they can access. Who needs your email password, when they have access to your whole mail file?

Even if we assume GNOME Keyring could be made attacker proof, we would need to do the same for every desktop application. An intruder could, in a few seconds, install a Trojan horse downloaded off the Internet that runs in the background and emails him your passwords as soon as your desktop applications use them. The same application could intercept your sudo password, and become root to access the GNOME Keyring data. Absolutely no technical skill is required to do this.

Leaving your desktop unattended exposes all your confidential data to an attacker, not just your passwords.

Game Over.

Recommendations:

• Always lock your screen when you leave your computer unattended. This is akin to locking your front door when leaving the house. Hit Ctrl-Alt-L, select “Lock Screen” from the user switch applet, or put the “Lock Screen” applet somewhere in your panel for easy access.
• Set a low screen-saver idle timeout, for example, 5 minutes. If you forget to lock your session, it will do so automatically after a couple of minutes, reducing the time your confidential data is exposed.

And remember: This isn't a security issue, and there is no good way to fix it.