18 November 2007

Fix setup of pulseaudio under GNU/Linux Fedora 8

It is important to ensure that pulseaudio is well installed, and used as wished.
After having installed the kde-settings-pulseaudio package (and perhaps something else ?), I have had issue with sound support.
There is lots of interesting information on the "The Perfect Setup" page of official pulseaudio site.

According to my needs, I have followed the instructions about "ALSA Applications" and "KDE" (mplayer and xmms works well without the given instructions).

Unfortunately, I have had still problems, and found that several other users have too.
The solution can be found into this topic:
- simply add the MODE="0666" mention after some instructions of the /etc/udev/rules.d/40-alsa.rules file,
- ensure there is no more /tmp/pulse-XXX (with XXX username) directory with not rights enough.

But it is not enough neither, additional information can be found on this topic, it solves my problem one for good.

17 November 2007

Hang problems under GNU/Linux Fedora 8

It seems there is several situations leading to kernel hang under GNU/Linux Fedora 8.
The bug 283161 report gives lots of information about solution.
For instance, this is kernel options which can be used (not all together):
- nohz=off highres=off
- clocksource=acpi_pm
- nolapic_timer

Unfortunately, I have tests all "sets" but without success.
Lots of tests and several discussions lead mind to potential graphical driver issue.
As soon as I have replaced use of radeon by vesa, I had no more problem (but I have had no time enough to keep on testing).
To benefit from my graphical card efficiencies, I have installed the last Fedora 7 radeon drivers version and have still no more issue (after having switched back use of those radeon drivers).

This is only a temporarily fix until an official solution is given.
I will report as soon as I would know about it.

Upgrade GNU/Linux Fedora from 7 to 8 (with yum)

Upgrade from Fedora 7 to Fedora 8 can be done with the same method I have explained into another post.
In addition, there is recommendations of Fedora project.
Eventually, this is additional instructions allowing to find potential issues with installed packages (need yum-utils package):
package-cleanup --problems
to find problems
package-cleanup --orphans
to list installed packages which are not available from currently configured repositories. It allows to find orphan installed packages which may be removed now.

Personally, I have had hang problems after upgrade (independent from it).
My next post will be linked to it, and known solutions.

9 October 2007

Make Microsoft Windows stops swapping

I've recently found something which should be very useful in various situation.
A register key to update to disable the swap of drivers and system.
It might be interesting after having minimized an application and let it during some times, for instance.
In other words, a performance improvement VS some more memory use.

I almost do not use Microsoft Windows anymore, so let me know if it does something for you ...

23 September 2007

Remove network interface under Solaris

Under Solaris, it is very more easy to remove than to add. The network interface can be found thanks to the couple (name, inet address):
N.B.: All checks have been removed for better legibility, but it is very important to check returned code after each request.

// We consider the existence of the variables (unsigned char *) "networkInterfaceName", "inetAddress" which could be respectively "eth0" and "" for instance.

int socketDescriptor;
struct sockaddr_in *addr;
struct lifreq lifr;

sd = socket(AF_INET, SOCK_DGRAM, 0);

memset(&lifr, 0, sizeof(lifr));
addr = (struct sockaddr_in *) &(lifr.lifr_addr);
strncpy(lifr.lifr_name, networkInterfaceName, sizeof(lifr.lifr_name));
addr->sin_family = AF_INET;
addr->sin_addr.s_addr = inet_addr(inetAddress);
ioctl(socketDescriptor, SIOCLIFREMOVEIF, (caddr_t) &lifr)

Remove network interface under GNU/Linux

It is enough to switch down the corresponding alias network interface:
N.B.: All checks have been removed for better legibility, but it is very important to check returned code after each request.

// We consider the existence of the variable (unsigned char *) "aliasInterfaceName" ("eth0:myAlias" for instance).
int sd;
struct ifreq ifr;

sd = socket(AF_PACKET, SOCK_RAW, htons(ETH_P_ALL));

memset(&ifr, 0, sizeof(struct ifreq));
strncpy(ifr.lifr_name, aliasInterfaceName, sizeof(ifr.ifr_name));
ifr.ifr_flags = ~IFF_UP;
ioctl(sd, SIOCSIFFLAGS, &ifr);

Add network interface under Solaris

Under Solairs, it is not trivial to add a network interface, there is no alias, and it seems to not be possible to specify the additional network interface name (so it must be got and kept).
N.B.: All checks have been removed for better legibility, but it is very important to check returned code after each request.

// We consider the existence of the variables (unsigned char *) "networkInterfaceName", "inetAddress", "broadcastAddress" and "netmaskAddress" which could be respectively "eth0", "", "" and "" for instance.

int sd;
struct sockaddr_in *addr;
struct lifreq lifr, lifrBroadcast, lifrNetmask, lifrFlags;
const char *aliasName;

// Resets structure.
memset(&lifr, 0, sizeof(lifr));
strncpy(lifr.lifr_name, networkInterfaceName, sizeof(lifr.lifr_name));

sd = socket(AF_INET, SOCK_DGRAM, 0);
ioctl(sd, SIOCLIFADDIF, (caddr_t) &lifr);

// Very important to get the alias name to update network interface parameters.
aliasName = lifr.lifr_name;

// Manages broadcast.
memset(&lifrBroadcast, 0, sizeof(lifrBroadcast));
addr = (struct sockaddr_in *) &(lifrBroadcast.lifr_broadaddr);
strncpy(lifrBroadcast.lifr_name, aliasName, sizeof(lifrBroadcast.lifr_name));
addr->sin_family = AF_INET;
addr->sin_addr.s_addr = inet_addr(broadcastAddress);
ioctl(sd, SIOCSLIFBRDADDR, (caddr_t) &lifrBroadcast);

// Manages netmask.
memset(&lifrNetmask, 0, sizeof(lifrNetmask));
addr = (struct sockaddr_in *) &(lifrNetmask.lifr_addr);
strncpy(lifrNetmask.lifr_name, aliasName, sizeof(lifrNetmask.lifr_name));
addr->sin_family = AF_INET;
addr->sin_addr.s_addr = inet_addr(netmaskAddress);
ioctl(sd, SIOCSLIFNETMASK, (caddr_t) &lifrNetmask);

// Defines the address of the new interface.
addr = (struct sockaddr_in *) &(lifr.lifr_addr);
addr->sin_family = AF_INET;
addr->sin_addr.s_addr = inet_addr(inetAddress);
ioctl(sd, SIOCSLIFADDR, (caddr_t) &lifr);

// Sets the new interface UP.
memset(&lifrFlags, 0, sizeof(lifrFlags));
strncpy(lifrFlags.lifr_name, aliasName, sizeof(lifrFlags.lifr_name));
ioctl(sd, SIOCGLIFFLAGS, (caddr_t) &lifrFlags)
lifrFlags.lifr_flags |= IFF_UP;
ioctl(sd, SIOCSLIFFLAGS, (caddr_t) &lifrFlags);

Add network interface under GNU/Linux

It is not so hard to perform it under GNU/Linux with alias.
The aim, is to add an alias to an existing network interface with the wished inet, broadcast and netmask addresses:
N.B.: All checks have been removed for better legibility, but it is very important to check returned code after each request.

// We consider the existence of the variables (unsigned char *) "aliasInterfaceName", "inetAddress", "broadcastAddress" and "netmaskAddress" which could be respectively "eth0:myAlias"; "", "" and "" for instance.

int sd;
struct sockaddr_in *addr;
struct ifreq ifr, ifrBroadcast, ifrNetmask;

sd = socket(AF_PACKET, SOCK_RAW, htons(ETH_P_ALL));

// Add alias.
memset(&ifr, 0, sizeof(ifr));
strncpy(ifr.lifr_name, aliasInterfaceName, sizeof(ifr.ifr_name));
addr = (struct sockaddr_in *) &(ifr.ifr_addr);
ioctl(sd, SIOCSIFADDR, &ifr);

// Manages broadcast.
memset(&ifrBroadcast, 0, sizeof(ifrBroadcast));
strncpy(ifrBroadcast.lifr_name, aliasInterfaceName, sizeof(ifrBroadcast.ifr_name));
addr = (struct sockaddr_in *) &(ifrBroadcast.ifr_addr);
ioctl(sd, SIOCSIFBRDADDR, &ifrBroadcast)

// Manages netmask.
memset(&ifrNetmask, 0, sizeof(ifrNetmask));
strncpy(ifrNetmask.lifr_name, aliasInterfaceName, sizeof(ifrNetmask.ifr_name));
addr = (struct sockaddr_in *) &(ifrNetmask.ifr_addr);
ioctl(sd, SIOCSIFNETMASK, &ifrNetmask);


Get MAC address under GNU/Linux or Solaris

This is a way to get MAC address of a network interface in C language.
Under GNU/Linux it can be done thanks to a RAW socket:
N.B.: All checks have been removed for better legibility, but it is very important to check returned code after each request.

// Consider a variable "networkInterfaceName" of type char * is defined ("eth0" for instance).
int sd;
struct ifreq ifr;
const unsigned char *hardwareAddress;

sd = socket(AF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
memset(&ifr, 0, sizeof(ifr));
setNameInIfreq(&ifr, networkInterfaceName);
hardwareAddress = (unsigned char *) &ifr.ifr_hwaddr.sa_data;

Under Solaris, it begins to be less easy, we need to use DLPI code:
// Consider a variable "devicePath" of type char * is defined ("/dev/eth0" for instance).
int sd;
dl_phys_addr_req_t dlpareq;
dl_phys_addr_ack_t *dlpaack;
struct strbuf msg;
char buf[128];
int flags = 0;
const unsigned char *hardwareAddress;

sd = open(devicePath, O_RDWR));
dlpareq.dl_primitive = DL_PHYS_ADDR_REQ;
dlpareq.dl_addr_type = DL_CURR_PHYS_ADDR;
msg.buf = (char *)&dlpareq;
putmsg(sd, &msg, NULL, 0);
dlpaack = (dl_phys_addr_ack_t *)buf;
msg.buf = (char *)buf;
msg.len = 0;
msg.maxlen = sizeof (buf);
getmsg(sd, &msg, NULL, &flags);
memcpy(hardwareAddress, &buf[dlpaack->dl_addr_offset], dlpaack->dl_addr_length);

22 September 2007

Computer science Experience Knowledge SHAring

For more understanding, the blog is now named "Computer science Experience Knowledge SHAring", which could be shortly called CEKSHA.

15 September 2007

Upgrade GNU/Linux Fedora (with yum)

Upgrade from Fedora core N to Fedora core N+1 can be done thanks to yum, although it is not really recommended.
I have successfully performed such upgrade from core 3 (perhaps core 2, I'm not sure), to core 4, then core 5 and finally core 6. Upgrade from Fedora core 6 to Fedora 7 fails with this way because of great distribution architecture update (core and extras merged).

This is steps which can be followed to perform such upgrade:
- open a terminal in run level 3,
- temporary set default run level to 3 (edit /etc/inittab file) to avoid potential problem with card detection or something else during next boot,
- ensure to have the last version of yum thanks to yum upgrade yum,
- clean the yum meta-data to avoid some rare conflict yum clean all,
- upgrade the release thanks to fedora-release (and fedora-release-notes from Fedora core 6) package(s)
For instance, from core 5 to core 6 : rpm -Uvh fedora-release fedora-release-notes
- finally upgrade the full system, ensuring to keep information about all progress into a file, thanks to yum upgrade 2>&1 |tee /tmp/systemUpgrade.log
- fix potential little problem like missing symbolic link (I had one about i686-redhat-linux-gnu one time),
- think to upgrade depositories if needed (livna, dries, dag ...),
- update the /etc/grub.conf or /etc/lilo.conf file according to your environment if you want to ensure the default use of a kernel,
- reboot.

8 September 2007

How to choose a *nix shell

Today, there is very lots of shells like sh, bash, csh, tcsh, ksh, zsh, ash ...
For various reasons, it makes sens to choose one, a time for all, although it is not so easy.
Personally, I have first chosen tcsh for its functionalities and its legibility very near the C language. On the first hand, it was not a bad choice because thanks to it, I had done all I had needed, on the other hand I had faced two issues.
The first was the fact that function does not exists under tcsh, and that alias become dirty very quickly.
The second, the more important, is this is not installed by default on all *nix operating systems.

The wish to create something which can be used on lots of operating system, particularly on GNU/Linux, Solaris, and Cygwin which was my first shell multi-OS need, my second and definitive choice has been for GNU/Bash. It resolves the two points and it perfectly fits my needs.

To lead me on this choice, I have read lots of articles and Web Site, and I have concluded that GNU/Bash is now embedded as installation base on almost all operating systems. In the case it would not, it can be used as sh compatible.

It is why, I think it is the best choice in most cases. If you have not made your choice, you might make this one too, it will be a guarantee of perenity and should answer to all your needs.

4 September 2007

Compile OpenVPN and TUN under Solaris

I've recently worked on Solaris and need to compile the source code of openVPN and TUN.
At first, it seemed easy but because of some compatibility issues, it was not.
You can follow those steps to get openvpn executable under Solaris:
- download the openVPN source code and uncompress it under [OPENVPN_DIRECTORY],
- download the TUN source code and uncompress it under [TUNE_DIRECTORY],
- copy the [TUNE_DIRECTORY]/solaris/if_tun.h file to [OPENVPN_DIRECTORY],
- edit the [OPENVPN_DIRECTORY]/tun.c file and add the #include "if_tun.h" line after the #include "tun.h" one,
- under [OPENVPN_DIRECTORY], execute ./configure --disable-lzo,
- ensure there is a make executable into your path, for instance create a symbolic link executing ln -s /usr/sfw/bin/gmake /usr/bin/make,
- then execute make under [OPENVPN_DIRECTORY],
- finally the openvpn executable is ready for Solaris.

Then, you can follow those steps to get the tun functionality under Solaris:
- create the subdirectory [TUNE_DIRECTORY] /solaris/sys,
- download the dditypes.h file and put it under [TUNE_DIRECTORY] /solaris/sys (it fixes an incompatibility issue),
- ensure there is a ld executable into your path, for instance create a symbolic link executing ln -s /usr/sfw/bin/gld /usr/bin/ld,
- execute make install under [TUNE_DIRECTORY],
- finally the tun functionality is ready for Solaris.

It is now possible to use openVPN and TUN under Solaris.

1 September 2007

Create a full and safe emails server under GNU/Linux

Not so easy ? right.
Anyway, almost one year ago, I've successfully followed a very interesting How To Forge Tutorial which allows me to have such a fully functional emails server. Because it is for my own purpose, there is only few users using it, and I so don't know how must it is scalable.

This emails server is very interesting thanks to its completeness and security. The system is compounded of :
- postfix for the MTA layer,
- courier-imap for mailboxes,
- clamAV, openssl, openldap, cyrus-sasl and courier-authlib-mysql for authentication and anti-virus,
- mysql for users configuration and administration,
- spamassassin, dcc, razor, pyzor and amavis-new for spamfilters.

It works perfectly under Fedora core 5, and Fedora core 6 with my additional instructions.
During my documentation research in 2006, I have read articles enough to think that this system should work on several others GNU/Linux distributions, although packages name/configuration may differ.

31 August 2007


Hi everybody,

The aim of this blog is simply to share knowledge earned into design/development/technical delicate and/or difficult situations in which loneliness takes all its meaning.
Like lots of other people, in my personal and professional activities, I face such situations like very specific shell scripts needs, object oriented programming, native source code under GNU/Linux, Sun Solaris ...
Documentation, source code and simply theories are sometimes so difficult to find that it would be a waste to not share acquired knowledge.
I'll try to share such information as regularly as time will allow ...

All the comments are welcomes. Do not hesitate to interact with me.