Category: Linux

Posted on

xguest

I just discovered and installed the _xguest_ package for Fedora 8 and 9. Here’s what it does:

> Installing this package sets up the xguest user to be used as a temporary account to switch to or as a kiosk user account. The account is disabled unless SELinux is in enforcing mode. The user is only allowed to log in via gdm [or the fast-user-swiching applet]. The home and temporary directories of the user will be polyinstantiated and mounted on tmpfs.

Here’s how to install it:

yum install xguest

I hit a brick wall when I first tried it. I thought my machine was in SELinux Enforcing mode, when it wasn’t — it was in Permissive mode. I fixed it using system-config-selinux.

It’s possible to change what the xguest user can do using system-config-selinux. I’ve attached a screenshot showing what capabilities can be granted or revoked.

SELinux Administration for xguest user

Posted on

Fedora 9 and the OpenJDK

Java development is getting easier under Linux because of Sun’s OpenJDK, which linux distributors like Fedora now include. No more need to go through the hassle of downloading it from Sun. Here’s how I installed it.

yum install java-1.6.0-openjdk-devel java-1.6.0-openjdk-javadoc java-1.6.0-openjdk-plugin

A downside is that the default fonts in some Java applications, like IntelliJ IDEA, look terrible. Fedora 9 includes the RedHat Liberation fonts, which stand in for Microsoft fonts. I went into IDEA’s configuration, and changed the default font from “Arial” to “Liberation Sans”. IDEA’s visual appearance is nearly, but not completely, _fontastic_ compared to what it was before.

Posted on

Visualize your hard drive using a TreeMap viewer

Every once in a while, I get low on disk space, and hunting for large directories or files to delete can be difficult manually. [Tree Map visualization](http://en.wikipedia.org/wiki/Treemap) tools make the job easier. There’s [WinDirStat](http://windirstat.info/) for Windows, [KDirStat](http://kdirstat.sourceforge.net) for KDE, and [Disk Usage Analyzer](http://live.gnome.org/GnomeUtils/Baobab) (baobab) for Gnome.

![TreeMap Image](http://library.gnome.org/users/baobab/stable/figures/baobab_fullscan.png.en)

Posted on

Fedora 9, NVidia, VMWare Server

I’ve upgraded four systems to Fedora 9 in the past couple of weeks. For those that have NVidia cards, it was a bumpy ride until NVidia released a [new driver](http://www.nvidia.com/object/linux_display_ia32_173.08.html). To install it as a pre-built RPM package, see [this blog post](http://nareshv.blogspot.com/2008/04/fedora-9-rawhide-and-latest-nvidia-179.html).

For the system that runs VMWare Server, it was necessary to [upgrade to version 1.0.6](http://www.howtoforge.com/vmware-server-installation-on-a-fedora9-desktop), which supports the 2.6.25 kernel shipped with Fedora 9.

Posted on

Open Source Security report from Coverity

[Coverity](http://www.coverity.com) has published it’s [Open Source Scan Report 2008](http://coverity.com/library/pdf/Coverity-Scan_Open_Source_Report_2008.pdf), which details the security status of several open source projects. Here’s my summary:

* The overall security of open source projects is improving.
* There’s a linear relationship between the amount of code and the amount of bugs.
* Surprisingly, there’s no relation between function length and defect density.

Projects with exceptionally low defect density include Amanda, NTP, OpenPAM, OpenVPN, Perl, PHP, Python, TCL, Postfix, Samba, curl, libvorbis and vim.

The top two security defects are

1. NULL pointer dereference
2. Resource leak

I got to preview [Coverity Prevent](http://www.coverity.com/html/prod_prevent.html) at a previous job, and it rocks at finding real bugs in code, with a very low rate of false positives.

Posted on

What programs are listening to the network?

Sometimes, I’d like to know what programs on my system are listening to the network, and to quote the Perl motto, “there’s more than one way to do it”. On Linux, there’s `lsof -Pi` and `netstat -p`. On Windows XP and Vista, there’s the built-in `netstat -b[v] -a` and a separate utility called [tcpview](http://technet.microsoft.com/en-us/sysinternals/bb897437.aspx). I’ve included example usages and outputs.

__lsof__ (Linux)

sudo lsof -Pni

COMMAND PID USER FD TYPE DEVICE SIZE NODE NAME
python 1886 root 4u IPv4 6621 TCP 127.0.0.1:2207 (LISTEN)
cupsd 1898 root 3u IPv4 6663 TCP 127.0.0.1:631 (LISTEN)
cupsd 1898 root 4u IPv6 6664 TCP [::1]:631 (LISTEN)
cupsd 1898 root 6u IPv4 6667 UDP *:631
sshd 1912 root 3u IPv4 6711 TCP *:22 (LISTEN)
httpd 20084 apache 4u IPv6 7293 TCP *:80 (LISTEN)
httpd 20085 apache 4u IPv6 7293 TCP *:80 (LISTEN)
httpd 20086 apache 4u IPv6 7293 TCP *:80 (LISTEN)
httpd 20087 apache 4u IPv6 7293 TCP *:80 (LISTEN)
httpd 20088 apache 4u IPv6 7293 TCP *:80 (LISTEN)
httpd 20089 apache 4u IPv6 7293 TCP *:80 (LISTEN)
httpd 20090 apache 4u IPv6 7293 TCP *:80 (LISTEN)
httpd 20091 apache 4u IPv6 7293 TCP *:80 (LISTEN)

__netstat__ (Linux)

sudo netstat -lp –inet –numeric-hosts

Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 0.0.0.0:ssh 0.0.0.0:* LISTEN 1912/sshd
tcp 0 0 127.0.0.1:ipp 0.0.0.0:* LISTEN 1898/cupsd
tcp 0 0 127.0.0.1:2207 0.0.0.0:* LISTEN 1886/python
udp 0 0 0.0.0.0:ipp 0.0.0.0:* 1898/cupsd

Where’s `httpd`? It should be there, and it is, when I exclude the `–inet` option:

Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 :::http :::* LISTEN 2038/httpd
tcp 0 0 ::1:ipp :::* LISTEN 1898/cupsd

__TcpView__ (Windows)

[Download](http://technet.microsoft.com/en-us/sysinternals/bb897437.aspx) and start TcpView. From the menu, choose File > Save. Here’s the output from the file.

Process Protocol Local Address Remote Address State
svchost.exe:1064 TCP jareds-xp:epmapi jareds-xp:0 LISTENING
System:4 TCP jareds-xp:microsoft-ds jareds-xp:0 LISTENING
svchost.exe:976 TCP jareds-xp:3389i jareds-xp:0 LISTENING
nxssh.exe:2032 TCP jareds-xp:11000 jareds-xp:0 LISTENING

__netstat__ (Windows)

Note that this runs quite slowly on Windows.

netstat -bva

Active Connections

Proto Local Address Foreign Address State PID
TCP jareds-xp:epmap jareds-xp.mydomain.com:0 LISTENING 1064
c:\windows\system32\WS2_32.dll
C:\WINDOWS\system32\RPCRT4.dll
c:\windows\system32\rpcss.dll
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\system32\ADVAPI32.dll
[svchost.exe]

TCP jareds-xp:microsoft-ds jareds-xp.mydomain.com:0 LISTENING 4
— unknown component(s) —
[System]

TCP jareds-xp:3389 jareds-xp.mydomain.com:0 LISTENING 976
— unknown component(s) —
c:\windows\system32\rpcss.dll
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\system32\ADVAPI32.dll
[svchost.exe]

TCP jareds-xp:11000 jareds-xp.mydomain.com:0 LISTENING 2032
[nxssh.exe]

TCP jareds-xp:3389 jareds-xp.mydomain.com:0 LISTENING 976
— unknown component(s) —
c:\windows\system32\rpcss.dll
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\system32\ADVAPI32.dll
[svchost.exe]

Posted on

Read Office 2007 documents on Linux

I’ve had a few occasions where I’ve needed to read Microsoft Office 2007 documents, even though I don’t have Office 2007. There are several approaches.

Office 2007 stores it’s files and a zip archive, with xml files inside. This means that they’re somewhat human readable. I’ve used unzip to extract the file, and poked around until I found the xml file that represented the document (word/document.xml for docx). This works fairly well for Word and Power Point documents, but I’m not so sure that it would be good for Excel files.

Novell has provided a [converter](http://odf-converter.sourceforge.net) that converts Office 2007 documents to Open Office documents, and allows Office 2007 to save in Open Office format. The command line converter appears to work well, in my limited experience. Thanks to [this blog post](http://www.oooninja.com/2008/01/convert-openxml-docx-etc-in-linux-using.html), here’s how I installed it on a Fedora/RedHat system:

* “mkdir converter“
* “cd converter“
* “wget http://download.go-oo.org/red-carpet/ooo-680/sled-10-sp-i586/odf-converter-1.1-7.i586.rpm“
* “rpm2cpio odf-converter*rpm | cpio -ivd“
* “sudo cp usr/lib/ooo-2.0/program/OdfConverter /usr/local/bin“
* “cd ..“
* “rm -rf converter“

Run it as follows:

* “OdfConverter /i example.docx“

Windows users with MS Word 2000, 2002 or 2003 can install the [Microsoft Office Compatibility Pack](http://office.microsoft.com/en-us/word/HA100444731033.aspx). For those without MS Word, there’s the read-only [word viewer](http://www.microsoft.com/downloads/details.aspx?FamilyId=3657CE88-7CFA-457A-9AEC-F4F827F20CAC&displaylang=en)

Mac OS X Tiger office applications reportedly open Office 2007 documents.

Mac, Linux and FreeBSD users can use an online document conversion service such as [http://www.docx2doc.com/](http://www.docx2doc.com/) and [http://docx-converter.com/](http://docx-converter.com/) — with the caveat it may be unwise to submit confidential or proprietary documents to a third party.

Posted on

Palm TX: There’s more than one way to install an application

When I got my Palm TX, I didn’t realize that the Palm Desktop software wasn’t completely compatible with Windows Vista. For example, I can’t install new palm apps via hot syncing. Here are some alternative install paths:

1. Attach the pdb files to an email, and send it to myself. Use VersaMail to retrieve the message, and install the pdb attachments.
1. Use the web browser to download and install a pdb file.
1. Have someone beam it using the IR interface.
1. Have someone send it using bluetooth.
1. Install from an SD card. I haven’t verified that this works.

While I’m at it, it seems like configuring Linux to hotsync with Palm devices can be a pain. As an alternative, I think I’ll get an SD card and use [nvbackup](http://handypalmstuff.sourceforge.net/) to backup to SD, and then copy the backup from SD to my Linux box and use it with JPilot.

There’s more than one way to do things, especially for a Palm equipped with built-in WiFi, bluetooth and an SD expansion card.

Posted on

Disk Encryption: Not as secure as I thought

Apparently, it’s easier than I thought to recover disk encryption keys from a stolen laptop computer. The attack works against “several popular disk encryption systems: BitLocker (a feature of Windows Vista), FileVault (a feature of Mac OS X), dm-crypt (a feature of Linux), and TrueCrypt”. Watch the demonstration video at [http://citp.princeton.edu/memory/](http://citp.princeton.edu/memory/).

> The root of the problem lies in an unexpected property of today’s DRAM memories. DRAMs are the main memory chips used to store data while the system is running. Virtually everybody, including experts, will tell you that DRAM contents are lost when you turn off the power. But this isn’t so. Our research shows that data in DRAM actually fades out gradually over a period of seconds to minutes, enabling an attacker to read the full contents of memory by cutting power and then rebooting into a malicious operating system.

Encrypting a disk drive _does_ increase the confidentiality of data. It’s just not as secure as once thought.

Sidenote: Software and hardware based [key loggers](http://en.wikipedia.org/wiki/Keystroke_logging) can reduce the security of encryption as well.

Posted on

‘iotop’ shows top I/O consumers

Want to know why your Linux box is sluggish? Some program is probably hogging disk I/O. I just discovered a cool utility that shows what programs are using the most disk I/O: [iotop](http://guichaz.free.fr/misc/). To install it on Fedora, run

yum install iotop

Otherwise, download and run [iotop.py](http://guichaz.free.fr/misc/iotop.py) — it requires Python 2.5+ and Linux kernel 2.6.20+