Category Archives: desktop

Jumpy KDE on a new T430

The KDE screen kept hanging every few seconds , and it drove me crazy, 
another error I've been seeing is in the messages log:

 

Jul  5 12:34:05 desktop kernel: [ 5807.441851] [drm:i915_hangcheck_ring_idle] *ERROR* Hangcheck timer elapsed… blt ring idle [waiting on 1688990, at 1688990], missed IRQ?
 
which kept repeating all the time.
 
I found a working solution at: 
 
the solution that worked for me is:

On Kernel 2.8.38: /sys/module/i915/parameters/semaphores is set to 0
On Kernel 2.8.39: /sys/module/i915/parameters/semaphores is set to 1

if i do the following:

sudo -i
echo 1 > /sys/module/i915/parameters/semaphores

The Bug is also gone on 2.8.38 …..

If i set semaphores on 2.8.39 to 0 as it is default on 2.8.38, the bug also appears.

 

also there is a comment there talkeing about setting it up in boot through grub (I didnt test this yet though):

 

you can put this option in /etc/default/grub to make the change permanent
replace following line:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

by
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash i915.semaphores=1"

 

now my KDE runs just fine :)

 

fix for the autoboot suggestion:

it didnt work, a working solution was to edit the /boot/grub/menu.lst file and add i915.semaphores=1  to the end of the kernel line.

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solaris 10 and vnc

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VNC is a server client method of connecting to a remote server,
the great thing about vnc is that you can see the remote server desktop, and work on it with a mouse just like its your local desktop.
another good thing about vnc is that its free for use for many distros.

There are main 2 major software companies that supply free vnc server and vnc cllient,
the first is realvnc and the second is tightvnc , from the tighvnc site:

TightVNC is a free remote control software package. With TightVNC, you can see the desktop of a remote machine and control it with your local mouse and keyboard, just like you would do it sitting in the front of that computer. TightVNC is:

  • free for both personal and commercial usage, with full source code available (GPL-licensed);
  • useful in remote administration, remote customer support, education, and for many other purposes;
  • cross-platform, available for Windows and Unix, compatible with other VNC software.

So these are 2 options for you to download a good free vnc viewer.

Solaris VNCserver configuration

and I say only viewer because now the Solaris 10 build 5 comes with the vncserver alredy inside.
all you need to do is to configure it.

This page on the SUN site will give you the detailed explanation on how to do things and what security patch you need to install fisrt ,but the instructions can be summed up in 4 lines:

mkdir -p /etc/dt/config

cp /usr/dt/config/Xservers    /etc/dt/config/Xservers

edit this file “/etc/dt/config/Xservers” and add these lines at the end:

:1  Local local_uid@none root /usr/X11/bin/Xvnc :1 -nobanner -AlwaysShared -SecurityTypes None -geometry 1024x768x24 -depth 24
:2  Local local_uid@none root /usr/X11/bin/Xvnc :2 -nobanner -AlwaysShared -SecurityTypes None -geometry 1024x768x24 -depth 24
:3  Local local_uid@none root /usr/X11/bin/Xvnc :3 -nobanner -AlwaysShared -SecurityTypes None -geometry 1024x768x24 -depth 24
And reboot the server.

The lines with the :1 :2 etc at the beginning, are the virtual displays you wish to server to have available for connections, you can add more by changing the numbers to :4 :5 etc.

when connecting to the server with the vnc viewer you need to express to which virtual display you want to connect by adding it to end of the server’s name or ip:

10.10.10.1:3

If you want to connect to virtual display number 3.

A security note – this configuration will allow passwordless access to the vnc screen – if someone logs in and leaves it open – the next user can just enter without a login.

A safer configuration is to require a password by using the -SecurityTypes VncAuth parameter. The Xvnc(1) man page describes password requirements.

VNC and Security

The vnc as a general is clear text, for a more secure connection there is a method of tunneling the vnc through a ssh session.
2 nice tutorials for vnc through ssh can be found here and here.
the second tutorial is using putty for the ssh connection – putty is another great freeware,
its a free ssh client for windows to connect to ssh servers.

If the server you wish to connect to through vnc is located withing your lan,
and you are relaxed about security for the users on it – if its a training server etc ,
you can just setup the vncserver without any safeguards,
but if you are connecting through an unsecured medium (AKA the internet)
you better add the ssh layer to it.

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I Like Good Linux Lists On The Morning

Lists are the magic word for SEO and link bait, and they catch the eye.

Well I sometimes bite too so here is the latest Linux links list I have fallen for:
15 Power tools for Linux that you cant afford to miss,
I havent checked all the links in the page yet, but I will.

And you should probably check out the whole blog,
It looks very promising and fun to read.
from their description:
Penguin Inside is a blog about Linux and Software Guides, How-TOs, Reviews.
The blog is dedicated to Linux Desktops.

Another Good list is from Smashing Magazine:
50 Beautiful Flash Websites , and thats a beutiful list of 50 stunning flash websites,
A couple that i liked the most are:

e-Content Solutions

econtent

and v5 Design

v5design_s

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Apache Active Directory Authentication

Apache server is a strong web server that can serve great open source application like Mediawiki which is a great solution for information sharing,
but what if you want to use Mediawiki to share information only for the local office active directory domain members?
Or even only to members of a specific group in the active directory?

In Apache you have a specific module called mod_ldap which allows you to use the Active Directory as an authentication server for your users,
so you can create a secure wiki branch for each department users.

To setup the apache server to use Active Directory as access manager you will need to make sure the mod_ldap was compiled with the apache server and that these lines are in the httpd.conf file:

LoadModule authnz_ldap_module modules/mod_authnz_ldap.so
LoadModule ldap_module modules/mod_ldap.so

If you have a Windows server installed with the xampp install of apache and mysql, you will have the module pre-compiled into the apache server,
however testing that it’s loaded can be done with:

C:\xampp\apache\bin\httpd.exe -t -D DUMP_MODULES
the output should have these lines:
authnz_ldap_module (shared)
ldap_module (shared)

Once you have the mod_ldap modules loaded you can add to the apache configuration file the user authentication support:

Any Authenticated user from the Domain:

<Location /Finance_Wiki>
Require valid-user
AuthType Basic
AuthName “Finance Wiki Access”
AuthBasicProvider “ldap”
AuthLDAPBindDN “CN=proxy_user,OU=sub_group,OU=main_group,DC=some,DC=domain,DC=com”
AuthLDAPBindPassword “proxy_user_pass”
AuthLDAPURL “ldap://pdc.some.domain.com:389/OU=main_group,DC=some,DC=domain,DC=com?sAMAccountName?sub?(objectClass=*)”
</Location>

The AuthLDAPBindDN and AuthLDAPBindPassword settings are for setting a user that will allow the apache server to browse the Active Directory structure,
the user created for this should have the minimum rights possible in the domain.

This specific apache configuration will allow any user from the domain to share the /Finance_Wiki folder, but if you want to allow access for a specific group you need to add this configuration line:

require ldap-group CN=groupname,OU=group.container,OU=main_group,DC=some,DC=domain,DC=com

This is the part that will require the active directory authentication for a specific group.

This way you can prepare a wiki branch for each group in your company to securely share internal files.

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Solution for Windows 7 samba connection problem

samba_linux

A fresh install of windows 7 might have a problem with samba shares,

if you setup samba logging you will see errors like this:

[2009/08/26 09:15:53, 3] smbd/connection.c:yield_connection(76)
yield_connection: tdb_delete for name  failed with error Record does not exist.
[2009/08/26 09:15:53, 3] smbd/server.c:exit_server(614)

although the user was able to connect from a different PC with a different operating system.

I found this great solution for the samba connection problem,

and to break it to a few simple steps:

  1. from the run command or from a cmd window run secpol.msc
  2. go to “Local Policies” -> “Security Options” -> “Network Security: LAN Manager authentication level”
  3. change to “LM and NTLM – use NTLMV2 session security if negotiated”
  4. Press the OK button

This solution worked just fine on a fresh windows 7 install.

Need Help Cleaning up your registry?

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How to Debug Samba Server and solve user connection problems

samba_linux

Samba is the server used to share files from a Linux server to the rest of the windows clients in an office,
it is  an easy to use server with simple defaults that will make the integration easy into any domain,
you can find on the samba main site some configurations samples and newer smb.conf samples to help ease the server into the domain.

But the harder part after setting the server is debugging problems with it,
like a user permission problem – can the user authenticate to the Microsoft domain server?
maybe he has a password problem? maybe he doesn’t have permission to access the share?

Setting up samba logging:

For starters you will find all the config files are at /etc/smb
the main config file is smb.conf,
other important files are smbusers and smbpasswd,
smbusers is a mapping file, to mask windows user as a linux user for access.

Now first thing to do when debugging is to setup the logging well,
so these are good log settings in the /etc/samba/smb.conf for debugging of the samba service:

log file = /var/log/samba/%m.log
syslog = 0
log level = 3 passdb:0 auth:0 winbind:0 vfs:0
vfs objects = full_audit

  • log file = /var/log/samba/%m.log                             the %m is substituted for the machine name.
  • syslog = 0                                                                             0 means only LOG_ERR will be sent to the syslog,
    If you want more info to be sent there change it to 3
  • log level = 3 passdb:0 auth:0 winbind:0 vfs:0        gives better control over which options to log
  • vfs objects = full_audit                                                  this allows for full details on which files are accessed by whom.

With this configuration all the machines log files will be found under /var/log/samba/*.log
for a sample, if you been trying to connect to the samba server from a machine named “boo1″
you should see in the log folder: /var/log/samba/boo1.log

You can search inside the folder by using “ls –latr” to find the newest files,
which will mean the windows clients that have been trying to connect to te samba server.

And “tail -100 machine_name.log” to view the errors you got if you couldn’t access the share.

Real life Debug sample:

from the file temp1.log:

nmbd/service.c:make_connection_snum(314)
user ‘temp1′ (from session setup) not permitted to access this share (share2)

This error means to that your user is known as temp1,
and temp1 doesn’t have permission to access the share “share2”
in which case you need to open the smb.conf and setup the permissions
for the user on this share to allow him access.

Inside smbusers you can map windows users to a specific unix user with this syntax:
unix_user = MY_DOMAIN\windows_user1 MY_DOMAIN\windows_user2 MY_DOMAIN\windows_user3

And then allow access to shares in the config by using the unix name:
valid users = unix_user

Checking access to the server and listing shares on it from commend line:

smbclient -L //server -U windows_user

You will be prompt for password, and if the settings are good, you will receive the shares listing from the server.

Connecting to a share on the server:
smbclient  //server/share -U windows_user

after answering the password you get a command line much like ftp:

smbclient //server/share -U builder
Password:
Domain=[MY_DOMAIN] OS=[Unix] Server=[Samba 3.0.33-3.7.el5_3.1]
smb: \>

mounting windows share on linux from fstab:

This will allow for automatic mount in case of server reboot:

\\server\share /unix_location  smbfs  credentials=/etc/samba.sharepasswd,uid=unix_user,gid=unix_group,ip=192.168.0.1,lfs 0 0

Contents of /etc/samba/.sharepasswd should be windows user and password to connect to the share:

username=windows_user

password=windows_pass

Getting info from a windows domain controller for samba debugging:

To list all the windows domain users from linux command line:

net rpc username -S icq-mdc1

replace “username” with a valid windows user name, to list all the users in the server,
you will need to know the user password as well.

This command can list the user groups from the domain controller:

net rpc user INFO username -S domain-server-name

replace “username” with a valid windows user name.

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Top 5 Budweiser Wassup Commercial

Some things leave an impression on people for many years,
even if they were meant to be short lived.

The Budweiser commercials are just damn good.
Every couple of years I watch them again and enjoy them like it’s the first time.

But you have to watch them in a good sequence – so here is my pick of the Budweiser Commercials:

The Original Budweiser Commercial:

The pizza version:

The girl invastion:

The wassabi version:

8 years later
The Budweiser Wassup Commercial has evolved to reflect the changes:

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Free Photo Editor – Top 4

There are many great photo and graphic software for a nice amount of dollars out there, but finding the few good applications that are also free is harder.

Here are a few good ones – both the online version and those you install on your desktop:

Online Photo Editor

The first one I like is from aviary.com :

aviary2

They have a flash interface for editing the image, which allows the app to work well in Linux as well as on windows, and its a decent enough image editor, but the most impressive application on their site is not the image editor but the color editor tool Toucan:

toucan2

What is so good about this tool? well, part of my job is to make graphs,
some of them are dynamic, some of them are RRD based or excel based, or just a static graph to show some stats to the management, but they should be nice to look at, and here is my problem as i have no sense for color picking, i usually get some ugly graphs.

Toucan color picking wheelbut this is where this tools steps in – it allows you to pick a group of colors that go well together.

you choose how many colors you need and it will help you group them from these options:

  • equidistant
  • Circular
  • Alternate

etc…

and you can save your color groups for later use:

Toucan clipboard

So this tool helps in creating good looking graphs…

Colorjack

now this is another nice color picking tool, it loads faster then Toucan,
and does the same work.

Another Online image editor

Pixlr

pixlr online photo editor

Pixlr gives an easy feel of photoshop application, while it is also a flash application which loads into your browser – no install needed.

The best part about this app is the tools it lets you use on the image you load into it:

  • Red eye reduction tool
  • Bloat
  • Pinch
  • Dodge
  • Smudge (my favorite as you can see in the image above)
  • gradient
  • crop

And many more, if you need to quickly edit an image, without buying a software to do that, pixlr can be a very handy tool.

Offline Free Image Editors

paint.net

cat_pumpkin2

This is a great easy to use image editor, its quickly installed and its very simple interface is smooth to work with, the great plus about this app is it will allow you to easily drop a print screen image on it and start editing and cropping it as needs be.

The only drawback for paint.net is that its using the .net framework, which is not Linux native (ha!),
which brings us to the finalist:

Free Linux Photo editor

Gimp !!!

gimp2

Gimp is the all time champion when it comes to Linux free image editors,
It is a very strong software with many options and features, and filters and brushes,
and people keep creating more free filters and brushes all the time.

gimp brush tool

It comes with a lot of default brushes, but you can easily download some beautiful brushes some other happy user created.

Creative Commons

Now – combine all or any of these tools together with free images downloaded which you can search for at the CC search web page and you are ready to create some fine images which you can use anywhere.

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