Changing display manager on Linux Mint using command

If you used to login to Linux using GUI, it means you were using X display manager. There are many display managers. Among popular ones are gdm, kdm, mdm and lightdm. You can change display manager using gui tools but you can also use command for that purpose. On Linux Mint (and i think on other debian-based distros), you can use this command (say you are using gdm):

dpkg-reconfigure gdm

A dialog will ask you whether you want to change to other installed display managers or not. You can replace mdm with other installed display manager.

That's all there is to it folk. Have fun! :D

Proxmox KVM usb passthrough

Open KVM monitor for your KVM machine in Proxmox GUI or in the command line with the following command:

# qm monitor 168
Entering Qemu Monitor for VM 168 - type 'help' for help
qm> 

Show the usb devices info from your host machine:

qm> info usbhost
  Bus 4, Addr 2, Port 1, Speed 12 Mb/s
    Class 00: USB device 046b:ff10, Virtual Keyboard and Mouse
  Bus 6, Addr 2, Port 2, Speed 1.5 Mb/s
    Class 00: USB device 0624:0294, Dell 03R874
  Bus 2, Addr 3, Port 1, Speed 480 Mb/s
    Class 00: USB device 0930:6533, DataTraveler 2.0
  Auto filters:
    Bus *, Addr *, Port *, ID 0930:6533

According to device “USB device 0930:6533” in the example, add the device to guest machine:

qm> device_add usb-host,id=myusb,vendorid=0x0930,productid=0x6533

Verify that the new usb device is added in your guest:

qm> info usb
  Device 0.1, Port 1, Speed 12 Mb/s, Product QEMU USB Tablet
  Device 0.3, Port 2, Speed 12 Mb/s, Product QEMU USB Hub
  Device 0.4, Port 2.1, Speed 480 Mb/s, Product DataTraveler 2.0

After using it, remove usb device from your guest:

qm> device_del myusb

If you run the command again, you will see the usb device is gone from your guest:

qm> info usb
  Device 0.1, Port 1, Speed 12 Mb/s, Product QEMU USB Tablet
  Device 0.3, Port 2, Speed 12 Mb/s, Product QEMU USB Hub

This has been tested in Proxmox 3.0/957f0862

Source

FreeRDP - The Free Remote Desktop Client for Linux

RDP stands for Remote Desktop Connection. It is a way to connect to Windows desktop/server. Default port is 3389. If you use Linux, there are 2 client programs: 

1. rdekstop is the old client. Support Windows XP,2000,NT,Windows Server 2012 R2.

2. freerdp resumes the work of rdesktop and support new MS authentication for remote desktop.

To connect to Windows, following is the example: 

xfreerdp -u login -p password 192.168.0.5

There are many other options. Just run xfreerdp -h to see them.

mplayer-gui error : Error in skin config file

After installing mplayer-gui package, I can't start it.

$ gmplayer

MPlayer 1.1-4.8 (C) 2000-2012 MPlayer Team

mplayer: could not connect to socket

mplayer: No such file or directory

Failed to open LIRC support. You will not be able to use your remote control.

Error in skin config file on line 6: PNG read error in /usr/share/mplayer/skins/default/main

Config file processing error with skin 'default'

After googling a bit, I found out that it was due to the png files in dir /usr/share/mplayer/skins/default. This is the default skin directory. To fix this error, I have to install ImageMagick package because I want to use the convert program to convert all of the png files to format png24. Thus,

cd /usr/share/mplayer/skins/default; for FILE in *.png ; do sudo convert $FILE -define png:format=png24 $FILE ; done

Rerun gmplayer and all should be fine.

Have fun!

UPDATE (02-10-2017)

It doesn't work on Ubuntu 16.04 (xenial) but there's a workaround here.

You can update your system with unsupported packages from this untrusted PPA by adding ppa:mc3man/mplay-skins to your system's Software Sources. (Read about installing) 

sudo add-apt-repository ppa:mc3man/mplay-skins
sudo apt-get update 

Now just upgrade the related package by running:

sudo apt-get upgrade 

Have fun!

New job, new place and new adventure

I have been working in a new place and environment for almost 6 months now. A lot has happened since in my life and i am very excited to begin blogging again.

I gained new knowledge in many areas of Linux, servers and networking. I dealt with 6 hypervisors here, many virtual machines on them, about 20 vlans, many vpns, many pfsenses, NAS, HAS, AD, win 2012 R2 and zimbra collaboration suite.

I need to master all of this and hopefully with my basic knowledge in Linux, AD and postfix, it will be easier to grasp them.

The most important things here are the bosses and colleagues. So far they are very helpful, friendly and supportive.

I will post more about my Linux work here soon. So stay tuned but don't hold your breath. :D

Cheers.

cannot ssh to server

If you got the following error when trying to connect to ssh server:

me@pluto ~]$ ssh -vvv -l you localhost.localdomain  
OpenSSH_6.2p2, OpenSSL 1.0.1k 8 Jan 2015
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 49: Applying options for *
debug2: ssh_connect: needpriv 0
debug1: Connecting to localhost.localdomain [192.168.5.11] port 22.
debug1: Connection established.
debug1: identity file /home/zamri/.ssh/identity type -1
debug1: identity file /home/zamri/.ssh/identity-cert type -1
debug1: identity file /home/zamri/.ssh/id_rsa type -1
debug1: identity file /home/zamri/.ssh/id_rsa-cert type -1
debug1: identity file /home/zamri/.ssh/id_dsa type -1
debug1: identity file /home/zamri/.ssh/id_dsa-cert type -1
debug1: identity file /home/zamri/.ssh/id_ecdsa type -1
debug1: identity file /home/zamri/.ssh/id_ecdsa-cert type -1
ssh_exchange_identification: Connection closed by remote host

Try putting this in /etc/host.allow:

sshd:ALL

It solved my problem. Your mileage may vary.

Book review: Implementing SAMBA 4

Samba is a Windows implementation of sharing files and folders in Linux world. It is a favorite way of sharing your files on Linux with Windows users. But its use is much more than that. It can also act as servers of various roles.

Implementing SAMBA 4 is a book worth reading for Linux admins, system engineers or anybody who plan to use and master SAMBA configurations. In this version, a new feature, Active Directory Domain Controller (AD DC) is the most sought after by admins. This will let you configure SAMBA 4 as an AD DC. Using Debian 7 as the OS, I found no problem with it although many admins out there are using Fedora/Red Hat/CentOS as the main distros of choice.

Looking at the table of contents, I can say this book is not for beginners. So you have been warned. :)

Reading the sample chapter provided (Chapter 3), this book is an interesting to read. Steps are shown in pictures and clearly explained. Although I have little knowledge of AD DC, this book will make it easier for you to understand the steps needed by lots of screenshots.

Other topics mentioned that I found important and interesting are:

• Understand the migration steps from Samba 3 to Samba 4
• Integrate GNU/Linux operating system authentication into the AD
• Understand the tasks and attention points when replacing a Microsoft Windows AD

If you are looking for a reading to better understand on how to configure SAMBA 4 for your AD DC, I recommend this kind of book.