Showing posts with label ubuntu. Show all posts
Showing posts with label ubuntu. Show all posts

[Linux/Ubuntu] How to fix graphic issues (nvidia display)

Hi,

Sometimes after usual system update/upgrade your graphic drivers can also get updated. On some occasions you may have few issues after such update including for example:

  • cannot login to the system
  • blank screen / black screen
  • login loop
  • and simialar

In order to fix it you will need to login to separate console, so first thing is:

CTRL + ALT + F2

And then try the following actions:

  • sudo apt-get update
  • sudo apt-get upgrade
  • sudo apt-get install gdm 
  • sudo dpkg-reconfigure lightdm // and choose lighttdm
  • sudo apt-get purge nvidia* // remove nvidia
  • sudo apt-get dist-upgrade
  • sudo apt-get install nvidia-current
  • sudo update-alternative --config i386-linux-gnu_gl_conf // or x86_64-linux-gnu_gl_conf 
  • // find out which version you got nvidia-xxx
  • then: sudo apt-get install nvidia-xxx-updates
  • sudo nvidia-xconfig
  • sudo reboot

A bit of command chaos but it did the trick :)

Permission problems for FAT filesystems (Ubuntu)

Hi,

Here is quick post about resolving problems with mounting FAT32 paritions on Ubuntu.

There are several ways to mount a partition, for example:
1. Manual by clicking on the device from the UI ('Places').
2. Configure FSTAB to do the job for you automatically.
3. Use GUI tools such as pysdm.
4. Manual from command line.

There might be a problem with permissions of writing or even accessing mounted fat partition. You can get message that you do not have permission to see the disk content or something similar.

Basically partition type of the fat file system is called VFAT in Unix based system. By default when you mount it the ownership of the place belongs to the root user. So you have to be a root to write files to the partition. Even more - you may also not be allowed to change ownership.

So to resolve this problems you can create an entry in /etc/fstab containing some special "settings" which will mount the partition for you with all required rights:

# device mount_point  type properties X Y
/dev/sda1 /media/directory  vfat umask=0000,rw,user 0 0


The key elements are the flags:
  • rw - mount as read and write (but it is not enough for fat devices)
  • user - permits any user to mount the filesystem
  • umask - gives actual permissions or rather resets it - this actually seems to resolve an issue with lack of permission for user due to root ownership
This topic, setting and flags could be discussed in more details but umask=0000 should do the trick.

VPN Nortel via vpnc on Ubuntu

You may want to use VPN Nortel connection via vpnc client on Ubuntu. The default version does not support it - I mean it does not allow you to use PIN-token authentication mode.

However there is a workaround!
 
First you will need to checkout the vpnc-nortel sources directly from the SVN repo. It would be good to have subversion and vpnc dependencies before so please run:
sudo apt-get install build-essential subversion

sudo apt-get build-dep vpnc

Then to checkout from SVN:

svn co -r 517 http://svn.unix-ag.uni-kl.de/vpnc/branches/vpnc-nortel

This will get the revision 517 which is the latest at the time of writing this post.

One minor step before building the sources is to edit the Makefile and set the PREFIX var to be /usr

Now you can build the sources:
make 
sudo make install


From now on you should be able to use it to connect via PIN-token authentication. Settings are stored in the /etc/vpnc where you can set default configuration by editing default.conf file. For example:

IPSec gateway <gateway_address>
IPSec ID <group_username_or_id>
IPSec secret <user_password>
Vendor nortel
Nortel Client ID V05_01
IKE Authmode PIN-token
Xauth username <auth_username>
Xauth PIN <pin>



To connect just run: sudo vpnc

To disconnect: sudo vpnc-disconnect

This is it. Cheers!


Microsoft Lync for Ubuntu / Linux

If you are Linux user and require to use Microsoft Lync communication you may have small problem. Currently it works only for Windows based systems or eventually for Macs.

So what can Linux user do?
Actually there is quite easy workaround. You can use Pidgin as general IM tool and install additional plugin which will get you connected with Lync users.

Follow the steps below:
  • sudo apt-get install pidgin
  • sudo apt-get install pidgin-sipe (this has specified plugin)
From now on you can add "Office Communicator" account to the Pidgin.

Provide your details (user name, psswd, etc.) and try to connect. It can offer to accept the certificate which is fine to do.

There might be 'READ ERROR' on connection. If so, run command below before starting Pidgin:

export NSS_SSL_CBC_RANDOM_IV=0

pidgin

However it may be annoying to type this extra bit every time you run the IM. In that case you may consider of writing small script to do that for you.

This solution has been tested under Ubuntu distribution but should also work for other cores.

Cheers!