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In my previous post about the Yubikey I suggested that computer users’ groups should arrange bulk purchases to get the best prices [1]. I ran such a buying club for Linux users in Australia as well as members of SAGE-AU [2].
The keys have arrived and I now have to start posting them out. Above is a picture of two boxes that each contain 100 keys. Presumably if you buy a smaller number of keys then you get more fancy packing.
Thanks to Yubico for giving us a greater discount than the usual discount rate for boxes of 100 keys!
Why use a Chroot environment?
A large part of the use of chroot environments is for the purpose of security, it used to be the only way of isolating a user from a section of the files on a server. In many of the cases where a chroot used to be used for security it is now common practice to use a virtual server. Also another thing to note is that SE Linux provides greater access restrictions to most daemons than a chroot environment would so in many case using SE Linux with a sensible policy is a better option than using a chroot environment to restrict a daemon. So it seems to me that the security benefits that can be obtained by using a chroot environment have been dramatically decreased over the last 5+ years.
One significant benefit of a chroot environment is that of running multiple different versions of software on one system. If for example you have several daemons that won’t run correctly on the same distribution and if you don’t want to have separate virtual machines (either because you don’t run a virtualisation technology or because the resources/expense of having multiple virtual servers is unacceptable) then running multiple chroot environments is a reasonable option.
The Simplest Solution
The simplest case is when all the chroot environments are equally trusted, that means among many other things that they all have the latest security patches applied. Then you can run them all with the same labels, so every file in the chroot environment will have the same label as it’s counterpart in the real root – this will mean that for example a user from the real root could run /chroot/bin/passwd and possibly get results you don’t desire. But it’s generally regarded that the correct thing to do is to have a chroot environment on a filesystem that’s mounted nosuid which will deal with most instances of such problems. One thing to note however is that the nosuid mount option also prevents SE Linux domain transitions, so it’s not such a good option when you use SE Linux as domain transitions are often used to reduce the privileges assigned to the process.
There are two programs for labeling files in SE Linux, restorecon is the most commonly used one but there is also setfiles which although being the same executable (restorecon is a symlink to setfiles) has some different command-line options. The following command on a default configuration of a Debian/Lenny system will label a chroot environment under /chroot with the same labels as the main environment:
setfiles -r /chroot /etc/selinux/default/contexts/files/file_contexts /chroot
I am considering adding an option to support chroot environments to restorecon, if I do that then I will probably back-port it to Lenny, but that won’t happen for a while.
For a simple chroot once the filesystem is labelled it’s ready to go, then you can start daemons in the chroot environment in the usual way.
Less trusted Chroot environments
A reasonably common case is where the chroot environment is not as trusted. One example is when you run an image of an old server in a chroot environment. A good way of dealing with this is to selectively label parts of the filesystem as required. The following shell code instructs semanage to add file contexts entries for a chroot environment that is used for the purpose of running Apache. Note that I have given specific labels to device nodes null and urandom and the socket file log in the /dev directory of the chroot environment (these are the only things that are really required under /dev), and I have also put in a rule to specify that no other files or devices under /dev should be labelled. If /dev is bind mounted to /chroot/dev then it’s important to not relabel all the devices to avoid messing up the real root environment – and it’s impractical to put in a specific rule for every possible device node. Note that the following is for a RHEL4 chroot environment, other distributions will vary a little some of the file names.
semanage -i – << END
fcontext -a -t root_t -f -d /chroot
fcontext -a -t bin_t “/chroot/bin.*”
fcontext -a -t usr_t “/chroot/usr.*”
fcontext -a -t usr_t “/chroot/opt.*”
fcontext -a -f -d /chroot/dev
fcontext -a -f -s -t devlog_t /chroot/dev/log
fcontext -a -f -c -t null_device_t /chroot/dev/null
fcontext -a -f -c -t urandom_device_t /chroot/dev/urandom
fcontext -a -t "<<none>>" "/chroot/dev/.*"
fcontext -a -t "<<none>>" "/chroot/proc.*"
fcontext -a -t lib_t “/chroot/lib.*”
fcontext -a -t lib_t “/chroot/usr/lib.*”
fcontext -a -t bin_t “/chroot/usr/bin.*”
fcontext -a -t httpd_exec_t -d — /chroot/usr/bin/httpd
fcontext -a -t var_t “/chroot/var.*”
fcontext -a -t var_lib_t “/chroot/var/lib.*”
fcontext -a -t httpd_var_lib_t “/chroot/var/lib/php.*”
fcontext -a -t var_log_t “/chroot/var/log.*”
fcontext -a -t var_log_t -f — “/chroot/var/log/horde.log.*”
fcontext -a -t httpd_log_t “/chroot/var/log/httpd.*”
fcontext -a -t var_run_t “/chroot/var/run.*”
fcontext -a -t httpd_var_run_t -f — /chroot/var/run/httpd.pid
fcontext -a -t httpd_sys_content_t “/chroot/var/www.*”
END
You could create a shell script to run the above commands multiple times for multiple separate Apache chroot environments.
If there is a need to isolate the various Apache instances from each other (as opposed to just protecting the rest of the system from a rogue Apache process) then you could start each copy of Apache with a different MCS sensitivity label which will provide adequate isolation for most purposes as long as no sensitivity label dominates the low level of any of the others. If you do that then the semanage commands require the -r option to specify the range. You could have one chroot environment under /chroot-0 with the sensitivity label of s0:c0 for it’s files and another under /chroot-1 with the sensitivity label of s0:c1 for it’s files. To start one environment you would use a command such as the following:
runcon -l s0:c0 setsid chroot /chroot-0 /usr/sbin/httpd
David Byrne gave an interesting TED talk about how changes to architecture drove changes to musical styles [1]. I think he does stretch the point a little. To a certain extent people develop the most complex instruments and the largest music halls that can be supported by the level of technology in their society – people with a hunter-gatherer civilisation play drums because they can build them and can carry them.
The NY Times has an interesting article about paternity leave in Sweden [2]. The Swedish government pays for a total of 13 months leave that can be split between parents for every child. Of those 13 months 2 months can only be taken by the father – and that is likely to increase to a minimum of 4 months of paternity leave after the next election.
Dan Meyer gave an interesting TEDX talk about how the current math curriculum in the US (as well as Australia and lots of other countries that do the same thing) is totally wrong [3]. His main point is that maths problems should be based on real-world use cases where not all needed data is immediately available and there is also useless data that must be discarded. He believes that the most important thing is developing mathematical problem solving skills – basically the things that I did for fun when I was in primary school are skills that need to be taught to high-school students…
The Atlantic magazine has an amusing article by Daniel Byman and Christine Fair about the incompetent Islamic terrorists [4]. In Afghanistan half the suicide bombers kill only themselves and the US government has a lot of evidence of Taliban soldiers practicing bestiality and collecting porn. Islamic extremist groups are staffed by people who are bad soldiers and bad Muslims.
Jon Masters wrote an interesting post titled “What Would Jesus Buy” about ethical purchasing decisions [5]. Jon references The Church of Stop Shopping which isn’t a real religious organisation but a street theatre activist group.
ZeroHedga has an insightful article comparing corporations and the US government to street gangs [6]. The conclusion is that when gangs take over a neighbourhood everyone has to join a gang for their own protection.
Hillel Cooperman gave an interesting TED talk about being obsessed with Lego [7]. He compares Lego fans to Furries and makes a good case for this comparison.
Marian Bantjes gave an interesting TED talk about her graphic art / graphic design work [8]. I’ve never seen anything quite like this.
Business Insider has an interesting article about oil cleanup, it seems that most people who worked on the Exxon Valdez disaster are now dead [9], s opposed to most people who worked in almost every other occupation at that time who are either still working or enjoying their retirement. The current gulf disaster is bigger, will require more workers for the cleanup, and can be expected to have a higher death toll. Some people claim that measures to reduce oil efficiency will impact the economy, how will millions of people who are chronically ill for the rest of their lives impact the economy?
The NY Times has an interesting article on “circle lenses” [10], contact lenses designed to make the eyes look larger. It’s illegal to sell contact lenses in the US without a prescription, but the latest trend is for women to buy them online in a variety of colors. The FDA should probably approve them, it would be better to have the quality controls you expect from a medical supply company instead of having people rely on Malaysian mail-order companies for the safety of their eyes.
Don Marti has written an interesting article about the economic decline in the US, he suggests making pension funds invest in local jobs [11]. Companies are supposed to act on behalf of their stock-holders, but US companies often have the majority of their stock owned by the pension funds of workers but they act on behalf of a small number of rich people who own a minority of the stock. Don’s article was inspired by Andy Grove’s article in Bloomberg about the stagnation in technological development that has been caused by off-shoring the manufacturing [12].
Neil Brown has completed a test release of a new Linux software RAID feature for arrays with multiple redundancy that have bad sectors [13]. When a disk gets a bad sector the current behavior is to kick it out of the array, if you have two such errors on a 3 disk RAID-1 or a RAID-6 array then you lose all redundancy and are at risk of catastrophic failure even though in most cases both disks will still mostly work. With this patch some regions of the disk may be excluded but it can provide redundancy for other stripes. Thanks Neil for your great work here, and all your previous work over the last 10+ years!
The RSPCA has a new campaign titled “Close the Puppy Factories” [14]. Dogs are kept in very poor conditions and forced to churn out puppies for their entire lives to supply pet stores. The RSPCA recommends that people buy puppies from registered dog breeders (not “registered dog breeding companies”) and ask to see the dog’s parents. They also recommend not buying from classified adverts or pet stores. Animal shelters have to euthenise huge numbers of unwanted animals, you can buy a pet dog or cat from an animal shelter for a small fee that covers the expenses related to housing and spaying it – and save that animal from being euthenised!
Maureen Dowd criticises the Catholic Church properly in an article for the New York Times [15]. The Catholic Church officially regards ordaining a woman and raping a child to be equally bad offenses.
Frank Rich wrote an interesting column for the New York Times about Mel Gibson [16]. He describes the destruction of Mel Gibson’s reputation as a symptom of changes in the culture in the US and also links it to the fall of Ted Haggard (who supported Gibson’s most notorious movie The Passion of the Christ).
ffmpeg
I’ve updated my SE Linux repository for Squeeze to include a modified version of the ffmpeg packages without MMX support for the i386 architecture. When MMX support is enabled it uses assembler code which requires text relocations (see Ulrich Drepper’s documentation for the explanation of this [1]). This makes it possible to run programs such as mplayer under SE Linux without granting excessive access – something which we really desire because mplayer will usually be dealing with untrusted data. In my past tests with such changes to ffmpeg on my EeePC701 have resulted in no difference to my ability to watch movies from my collection, the ones that could be played without quality loss on a system with such a slow CPU could still be viewed correctly with the patched ffmpeg.
$ mplayer
mplayer: error while loading shared libraries: /usr/lib/i686/cmov/libswscale.so.0: cannot restore segment prot after reloc: Permission denied
The AMD64 architecture has no need for such patches, presumably due to having plenty of registers. I don’t know whether other architectures need such patches, they might – the symptom is having mplayer abort with an error such as the above when running in Enforcing Mode.
The below apt sources.list line can be used to add my SE Linux repository:
deb http://www.coker.com.au squeeze selinux
dpkg
In my repository for i386 and AMD64 architectures I have included a build of dpkg that fixes bug #587949. This bug causes some sym-links and directories to be given the wrong label by dpkg when a package is installed. Usually this doesn’t impact the operation of the system and I was unable to think of a situation where it could be a security hole, but it can deny access in situations where it should be granted. I would appreciate some help in getting the patch in a form that can be accepted by the main dpkg developers, the patch I sent in the bug report probably isn’t ideal even though it works quite well – someone who knows absolutely nothing about SE Linux but is a good C coder with some knowledge of dpkg could beat it into shape.
In my repository I don’t currently provide any support for architectures other than i386 and AMD64. I could be persuaded to do so if there is a demand. How many people are using Debian SE Linux on other architectures? Of course there’s nothing stopping someone from downloading the source from my AMD64 repository and building it for another architecture, I would be happy to refer people to an APT repository that someone established for the purpose of porting my SE Linux packages to another architecture.
Policy
selinux-policy-default version 20100524-2 is now in Testing. It’s got a lot of little fixes and among other things allows sepolgen-ifgen to work without error which allows using the -R option of audit2allow – see my post about audit2allow and creating the policy for milters for defails [2].
I have uploaded selinux-policy-default version 20100524-3 to Unstable. It has a bunch of little fixes that are mostly related to desktop use. You can now run KDE4 on Unstable in enforcing mode, login via kdm and expect that everything will work – probably some things won’t work, but some of my desktop systems work well with it. I have to admit that not all of my desktop systems run my latest SE Linux code, I simply can’t have all my systems run unstable and risk outages.
Let me know if you find any problems with desktop use of the latest SE Linux code, it’s the focus of my current work. But if you find problems with chrome (from Google) or the Debian package chromium-browser then don’t report them to me. They each use their own version of ffmpeg in the shared object /usr/lib/chromium-browser/libffmpegsumo.so which has text relocations and I don’t have time to rebuild chromium-browser without text relocations – I’ll make sure it does the right thing when they get it working with the standard ffmpeg libraries. That said the text relocation problem doesn’t seem to impact the use of Chromium, Youtube doesn’t work even when the browser is run in permissive mode.
GNOME is a lower priority than KDE for me at this time. But the only area where problems are likely to occur is with gdm and everything associated with logging in. Once your X session starts up GNOME and KDE look pretty similar in terms of access control. I would appreciate it if someone could test gdm and let me know how it goes. I’ll do it eventually if no-one else does, but I’ve got some other things to fix first.
Since the earliest days there has been a command named audit2allow that takes audit messages of operations that SE Linux denied and produces policy that will permit those operations. A lesser known option for this program is the “-R” option to use the interfaces from the Reference Policy (the newer version of the policy that was introduced a few years ago). I have updated my SE Linux repository for Lenny [1] with new packages of policy and python-sepolgen that fix some bugs that stopped this from being usable.
To use the -R option you have to install the selinux-policy-dev package and then run the command sepolgen-ifgen to generate the list of interfaces (for Squeeze I will probably make the postinst script of selinux-policy-dev do this). Doing this on Lenny requires selinux-policy-default version 0.0.20080702-20 or better and doing this on Debian/Unstable now requires selinux-policy-default version 0.2.20100524-2 (which is now in Testing) or better.
Would it be useful if I maintained my own repository of SE Linux packages from Debian/Unstable that can be used with Debian/Testing? You can use preferences to get a few packages from Unstable with the majority from Testing, but that’s inconvenient and anyone who wants to test the latest SE Linux stuff would need to include all SE Linux related packages to avoid missing an important update. If I was to use my own repository I would only include packages that provide a significant difference and let the trivial changes migrate through Testing in the normal way.
The new Lenny policy includes a back-port of the new Milter policy from Unstable, this makes it a lot easier to write policy for milters. Here is an example of the basic policy for two milters, it allows the milters (with domains foo_milter_t and bar_milter_t) to start, to receive connections from mail servers, and to create PID files and Unix domain sockets.
policy_module(localmilter,1.0.0)
milter_template(foo)
files_pid_filetrans(foo_milter_t, foo_milter_data_t, { sock_file file })
milter_template(bar)
files_pid_filetrans(bar_milter_t, bar_milter_data_t, { sock_file file })
allow bar_milter_t self:process signull;
type bar_milter_tmp_t;
files_tmp_file(bar_milter_tmp_t)
files_tmp_filetrans(bar_milter_t, bar_milter_tmp_t, file)
manage_files_pattern(bar_milter_t, tmp_t, bar_milter_tmp_t)
After generating that policy I ran a test system in permissive mode and sent a test message. I ran audit2allow on the resulting AVC messages from /var/log/audit/audit.log and got the following output:
#============= bar_milter_t ==============
allow bar_milter_t bin_t:dir search;
allow bar_milter_t bin_t:file getattr;
allow bar_milter_t home_root_t:dir search;
allow bar_milter_t ld_so_cache_t:file { read getattr };
allow bar_milter_t lib_t:file execute;
allow bar_milter_t mysqld_port_t:tcp_socket name_connect;
allow bar_milter_t net_conf_t:file { read getattr ioctl };
allow bar_milter_t self:process signal;
allow bar_milter_t self:tcp_socket { read write create connect setopt };
allow bar_milter_t unlabeled_t:association { recvfrom sendto };
allow bar_milter_t unlabeled_t:packet { recv send };
allow bar_milter_t urandom_device_t:chr_file read;
allow bar_milter_t usr_t:file { read getattr ioctl };
allow bar_milter_t usr_t:lnk_file read;
#============= foo_milter_t ==============
allow foo_milter_t ld_so_cache_t:file { read getattr };
allow foo_milter_t lib_t:file execute;
allow foo_milter_t mysqld_port_t:tcp_socket name_connect;
allow foo_milter_t net_conf_t:file { read getattr };
allow foo_milter_t self:capability { setuid setgid };
allow foo_milter_t self:tcp_socket { write setopt shutdown read create connect };
allow foo_milter_t unlabeled_t:association { recvfrom sendto };
allow foo_milter_t unlabeled_t:packet { recv send };
Running the audit2allow command with the “-R” option gives the following output, it includes the require section that is needed for generating policy modules:
require {
type sshd_t;
type ld_so_cache_t;
type bar_milter_t;
type foo_milter_t;
class process signal;
class tcp_socket { setopt read create write connect shutdown };
class capability { setuid setgid };
class fd use;
class file { read getattr };
}
#============= bar_milter_t ==============
allow bar_milter_t ld_so_cache_t:file { read getattr };
allow bar_milter_t self:process signal;
allow bar_milter_t self:tcp_socket { read write create connect setopt };
corecmd_getattr_sbin_files(bar_milter_t)
corecmd_search_sbin(bar_milter_t)
corenet_sendrecv_unlabeled_packets(bar_milter_t)
corenet_tcp_connect_mysqld_port(bar_milter_t)
dev_read_urand(bar_milter_t)
files_read_usr_files(bar_milter_t)
files_read_usr_symlinks(bar_milter_t)
files_search_home(bar_milter_t)
kernel_sendrecv_unlabeled_association(bar_milter_t)
libs_exec_lib_files(bar_milter_t)
sysnet_read_config(bar_milter_t)
#============= foo_milter_t ==============
allow foo_milter_t ld_so_cache_t:file { read getattr };
allow foo_milter_t self:capability { setuid setgid };
allow foo_milter_t self:tcp_socket { write setopt shutdown read create connect };
corenet_sendrecv_unlabeled_packets(foo_milter_t)
corenet_tcp_connect_mysqld_port(foo_milter_t)
kernel_sendrecv_unlabeled_association(foo_milter_t)
libs_exec_lib_files(foo_milter_t)
sysnet_read_config(foo_milter_t)
To get this working I removed the require lines for foo_milter_t and bar_milter_t as it’s not permitted to both define a type and require it in the same module. Then I replaced the set of tcp_socket operations { write setopt shutdown read create connect } with create_socket_perms as it’s easiest to allow all the operations in that set and doesn’t give any security risks.
Finally I replaced the mysql lines such as corenet_tcp_connect_mysqld_port(foo_milter_t) with sections such as the following:
mysql_tcp_connect(foo_milter_t)
optional_policy(`
mysql_stream_connect(foo_milter_t)
‘)
This gives it all the access it needs and additionally the optional policy will allow Unix domain socket connections for the case where the mysqld is running on localhost.
I’ve just done some quick research on Digital Video Cameras for some relatives. It seems to me that the main feature that is necessary is Full HD (1920*1080) resolution as everyone seems to be getting 1920*1080 resolution monitors (getting smaller doesn’t save enough money to be worth-while). Resolutions higher than 1920*1080 will probably available in affordable monitors in the next few years, so the ability of programs like mplayer to zoom videos will probably be required even for Full HD video soon. Saving maybe $300 on a video camera while getting a lower resolution doesn’t seem like a good idea.
The next feature is optical zoom, most cameras are advertised with features such as “advanced zoom” to try and trick customers, cameras which advertise 60* or better zoom often turn out to only have 20* zoom. I think that about 20* optical zoom should be considered the minimum, not that there is anything special about 20* zoom, it’s just that there is a good range of cameras with better zoom capacity.
Image stabilisation is a required feature, no-one can keep their hand perfectly steady and the typically a DVC only gets hand-held use – most people who own them don’t even own a tripod! Digital image stabilisation is apparently not nearly as good as optical image stabilisation, and image stabilisation that involves moving the CCD is apparently somewhere in between.
Finally it’s good to have the ability to take quality photos as few people will want to carry a Digital Camera and a Digital Video Camera.
I did a search for DVCs on the web site of Ted’s Camera store (a chain of camera stores in Australia that generally provide good service at a competitive price – but not the cheapest price). The best of the Ted’s options seems to be the Panasonic SD60 HD Video [1] which does 25* optical zoom, 1920*1080i video, 5 megapixel still photography, and optical image stabilisation – it costs $750 from Ted’s.
The next best option seems to be the Sony Handycam HDR-CX110 HD [2] which does 25* optical zoom, 1920*1080i video, 3.1 megapixel 2048*1536 still photography, and digital image stabilisation. The Panasonic seems to be a better option due to having optical image stabilisation and a higher resolution for still photographs. It is also $750 from Ted’s.
Now there’s the issue of how well the cameras work on Linux. A quick Google search indicated that the Sony cameras present themselves as USB card readers and can be mounted on a Linux system, I couldn’t discover anything about the Panasonic. If I was going to buy one I would take my Netbook to the store and do a quick test.
I don’t have enough information to recommend either of those cameras, they may have some awful defects that are only apparent when you use them. But in terms of features they seem pretty good. The Panasonic SD60 HD Video should be a good benchmark when comparing cameras in the store. If nothing else the camera store staff seem to not be very helpful if asked generic questions such as “which camera is best”, but if asked questions such as “how is this other camera better than the one I’m looking at” they can usually give good answers.
If anyone has any other advice for purchasing a DVC then please let me know. Either generic advice or specific examples of Linux-friendly DVCs that have been purchased recently.
One of the access controls in SE Linux is for execmem – which is used to stop processes from creating memory regions that are writable and executable (as they make it easier to compromise programs and get them to execute supplied code). When the SE Linux audit log tells you that a program is attempting such access it’s sometimes difficult to discover where in the code such an access occurs, for example if you have a large code base and mmap() is called in many places it can be difficult to determine which one is the culprit. Especially if you have a source package that contains multiple binaries that use a common shared library and you don’t know which bits of library code are called by each executable.
To solve this problem in the case of freshclam to provide extra information for Debian bug report #588599 [1] I wrote the following little shared object which can be compiled with “gcc -shared -g -fPIC mmap.c -o mmap.so” and used with “LD_PRELOAD=./mmap.so whatever“. Then when the program in question (or any non-SUID program it executes) calls mmap() with both PROT_EXEC and PROT_WRITE set the program will abort. If you run this through gdb then the program will break and you will get a back-trace of the function calls that led to the undesired mmap().
One thing to note is that this method only catches direct calls to a library function outside libc. When the libc code calls the library function (EG all the fwrite() etc code that calls mmap()) the LD_PRELOAD hack won’t catch it. Thanks to Keith Owens for pointing this out.
#include <dlfcn.h>
#include <stdio.h>
#include <sys/mman.h>
#include <stdlib.h>
#undef NDEBUG
#include <assert.h>
void *libc6 = NULL;
void *(*real_mmap)(void *, size_t, int, int, int, off_t);
void do_init()
{
libc6 = dlopen("libc.so.6", RTLD_LAZY | RTLD_GLOBAL);
if(!libc6)
{
printf("Aieee\n");
exit(1);
}
real_mmap = (void * (*)(void *, size_t, int, int, int, off_t))dlsym(libc6, "mmap");
}
void *mmap(void *addr, size_t length, int prot, int flags, int fd, off_t offset)
{
if(!real_mmap)
do_init();
assert(!(prot & PROT_EXEC) || !(prot & PROT_WRITE));
return real_mmap(addr, length, prot, flags, fd, offset);
}
My parents have just got a mobile phone with a Lebara pre-paid SIM [1]. Lebara advertise free calls to other Lebara phones but have a disclaimer that they charge a 25 cent flagfall and charge 15 cents per minute after the first 10 minutes – which is still cheaper than most mobile calls although not as good as some other mobile telcos such as Three that offer completely free calls to other phones with the same provider.
Lebara’s main selling point seems to be cheap international calls, half a cent per minute to Thailand, 1 cent per minute to Hong Kong, Indonesia and Singapore and 3 cents per minute to Bangladesh and China. Strangely calls to the US are 5 cents per minute and to Japan are 7 cents per minute, I would have expected that calling developed countries would have been cheaper due to better infrastructure and more competition. The trend of more developed countries having less expensive calls seems clear, some very undeveloped countries cost as much as $2 per minute! Note that all these rates are for calls to land-lines (calls to mobiles cost more) and are based on the new prices that apply after the 13th of July (it’s slightly cheaper for the next 8 days).
It seems really strange that calls to land-lines in Australia cost 15 cents per minute which is more than twice as much as calls to the US and Japan. In theory it would be possible to redirect calls to Australian land-lines via the US or Japan to save money. In practice it’s probably possible to do so by setting up a PBX in Thailand, Hong Kong, or Singapore.
But what I think is most noteworthy about Lebara is the fact that the call credit lasts for 90 days (this is in the FAQ). The cheapest top-up is $10 so therefore the minimum cost for mobile phone service is $40 per annum. Given the importance of owning a mobile phone to job seekers I think that with the current state of the economy there are a lot of people who could do with such a phone.
If anyone knows of Australian mobile phones that provide cheaper calls to other countries or a cheaper minimum annual fee then please let me know via the comments section.
For international readers, all prices are in Australian cents – which are worth about 85% as much as US cents.
Recently I have been doing a bit of work on libcsoap (the C library for making SOAP XML calls over http) and the libnanohttp library that it depends on. The most important part of my work on it was making it thread-safe with the technique I described in my post about finding thread unsafe code [1]. But I also did some work to make the code faster, reading data one byte at a time is very inefficient.
There has been no upstream release of this software for years, email to one of the maintainers bounced and the other one indicated that they are no longer involved in the project. So I’m thinking of taking over upstream development.
The previous Debian maintainer for the packages in question has recently resigned so I’ve taken over the packaging. But for this one I think I can do better work in an upstream capacity, so I’d like to get a co-maintainer for the Debian package and possibly someone who will help with upstream work. I would appreciate any offers of assistance with these things.
My SE Linux Play Machine [1] has been offline for almost a month (it went offline late May 30 and has just gone online again). It’s the sort of downtime that can happen when you use Debian/Unstable.
For a while I’ve been using a HP E-PC (a SFF desktop system with 256M of RAM and a P3-800 CPU) to run my SE Linux Play Machine. I run it under Xen to make it easier for me to watch what happens. I’ve had some problems with increased memory use in the Xen Dom0 in Squeeze [2]. The latest installment of the memory problems is when I discovered that I can’t run two copies of tcpdump (for tracing separate interfaces) at once on a Xen Dom0 that has ~110M of RAM – this seems unreasonable, I’m sure that back when a big server had 128M of RAM I could have done such things! So now I’m using a Thinkpad T20 with 512M of RAM for my new SE Linux Play Machine, it uses less power than most systems (probably even less than the HP E-PC) and is very quiet.
I was forced to install on a new system when I broke my GRUB configuration. GRUB-2 in Debian currently has no support for generating a configuration that will boot a Xen Dom0. You can manually edit the GRUB configuration to get this working, but if you get it wrong then you can make GRUB not even display a prompt and force a reinstall (as I did). As an aside it would be really handy if someone would create a CD or USB bootable image that does nothing but install GRUB. Such an image would ideally allow replacing the configuration of an existing GRUB, overwriting an existing GRUB installation (all files in /boot/grub get replaced), or formatting a spare partition (default swap space) and installing GRUB there.
My current solution to the GRUB problems is to use the old version of GRUB in the grub-legacy package. The old version of GRUB has always done everything I want so I don’t seem to be missing anything by not using the new version. I’m happy to refrain from using Ext4 for /boot and have no desire to have /boot on an LVM volume.
Most of the month of down-time for my Play Machine was caused by bugs in the SE Linux policy I’m developing for Squeeze, while they weren’t difficult bugs I haven’t had much time to work on them consistently. I’m still running the Play Machine on Lenny, but the Dom0 is running Unstable.
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