How to Set Up Password-less SSH Login on Linux

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Automatic passwrod-less ssh login can make our life easier. To enable this, we have 2 options: using key-based authentication by copying our SSH public keys to the remote machines for automatic password-less login or using password-based authentication. I will introduce the 2 options in the post. Before you start, please note that key-based authentication is
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How to Capture Desktop Video on Linux using ffmpeg

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ffmpeg is a powerful tool and it can do the work of capturing Linux desktop video very well. ffmpeg is a very fast video and audio converter that can also grab from a live audio/video source. ffmpeg can grab X11 input and create a video file such as mp4 at specific fps with the specific
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How to Install MPlayer and MEncoder on Fedora

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Fedora does not include MPlayer or MEncoder for some reasons in its official repositories. But RPMfusion does it for us. Let’s install mplayer and mencoder and learn some tricks to play rmvb files. 1. Add RPMfusion repository: Table of Contents 1. Add RPMfusion repository:2. Install MPlayer and MEncoder3. Get codecs4. Enjoy it!5. Play rmvb files
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Installing akmod NVIDIA Driver on Fedora

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Installing akmod NVIDIA driver from rpmfusion on Fedora 12. First make sure your nvidia card is in “Supported NVIDIA GPU Products List”: Click here for the list 1. Add rpmfusion repository: Table of Contents 1. Add rpmfusion repository:2. Install akmod nvidia driver3. Add nouveau to blacklist in grub.conf4. Enable allow_execstack in SELinux5. Reboot Enable RPM
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Sending Email Using mailx/s-nail in Linux Through Gmail SMTP

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The heirloom mailx (or s-nail if you are using Ubuntu 18 or later or similar releases) command in Linux is still providing service for guys like me, especially when we need to send email automatically by script. Gmail is great. Now, how to use gmail’s smtp in mailx/mail? gmail is a little special since gmail’s
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Setting Up Linux Network Gateway Using iptables and route

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Sharing the networking is important and setting up a gateway is a good solution to it. Building up the gateway on a Linux box is easy, cost efficient and reliable. With a Linux box, you can share the internet connection or the only cable connected to the network. The Linux box network configuration Table of
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Guake: An Excellent Quake Like Drop-down Terminal for Gnome

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Guake is very fast and stable enough for use. It’s an excellent quqke like drop-down terminal for gnome. I used yakuake on KDE. It’s professional but a bit slow. I used tilda also on gnome. But unfortunately, there are too many bugs. Then after I find Guake, I am happy. Guake is invoked with a
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How to Control or Disable SELinux in Fedora and CentOS Linux

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For most of cases, you should not disable SELinux. However, for some users, SELinux may cause problems or is not needed. We may just make it not block operations or totally disable it. Making SELinux log warnings instead of blocking Table of Contents Making SELinux log warnings instead of blockingTemporarily disable SELinuxPermanently disable SELinuxChecking SELinux
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How to Set Up Socks Proxy Using SSH Tunnel

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We can set up a socks proxy on top of a SSH tunnel. Besides the common proxy functions, such as web browsing, the proxy on top of SSH tunnel also ensures the security between the browser and the proxy server (the SSH server). In this post, we introduce and explain how to set up a
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Automatically Backing Up Xen File-backed DomU

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A script for backing up file-backed Xen DomU is introduced in this post. This script can be changed to similar platform. In our cluster, virtual machines are stored under /lhome/xen/. Virtual machine with id vmid is stored in directory vmvmid. The raw image disk file name can also be derived from vmid. Some more details
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Unified Xen DomU configuration file

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Previously, we create a configuration file for each DomU virtual machines in our cluster. Most of the content in these configuration files is the same. The differences are only the name, memory size and image file address. There are several disadvantages of this method: We must create and configure a new configuration file when creating
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An I/O Performance Comparison Between loopback Backed and blktap Backed Xen File-backed VBD

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I have done some I/O performance benchmark test of Xen DomU. For easier management, some of our DomU VMs are using file-backed VBDs. Previously, our VMs are using Loopback-mounted file-backed VBDs. But blktap-based support are recommended by Xen community. Before considering changing from loopback based VBD to blktap based VBD, I have done this performance
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lftp Disable SSL

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lftp some times stalls with message “Making data connection” when “ls” the directory after logged in the ftp site. The message may appear like this: < — 227 Entering Passive Mode (xx,xx,xx,xx,xx,xx) —- Connecting data socket to (yy,yy,yy,yy) port zz `ls’ at 0 [Making data connection…] But some client such as filezilla may works on
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How to Flush DNS Cache of Linux and Windows Client

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We may need to flush DNS cache of our client when the site’s DNS has been changed. Flush DNS cache of Linux with NetworkManager/dnsmasq Table of Contents Flush DNS cache of Linux with NetworkManager/dnsmasqFlush DNS Cache on (Old) Linux with nscdFlush DNS Cache on Windows:Flush DNS cache of Chrome You may simply restart NetworkManager by
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Mostly Used MPlayer Keyboard Control Shortcuts

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MPlayer has a fully configurable, command-driven control layer which allows you to control MPlayer using keyboard. But which are these shortcuts are not immediately know to users of MPlayer. Below is a list of mostly used MPlayer keyboard control shortcuts. They come from the [[man:1|mplayer|mplayer manual]] where you can find a full list of all
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How to Remote Control Linux Server Using VNC through SSH Tunnel

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Sometimes we need to have the GUI of some application on the remote server. ssh’s X11 forwarding with “-X” parameter is a good and fast method. But if we want to have a whole desktop environment, vnc is a good choice. In this post, the method of how to control remote server using vnc through
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A Simple CPU and Memory Performance Test of Xen Dom0 and DomU

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Please refer to Setting Up Xen Dom0 on Fedora : Xen 3.4.1 with Linux Kernel 2.6.29 on Fedora 12 for the platform of this test (this test runs on Fedora 11, however). I have done some simple performance test on DomU and Dom0 and compare with the performance on physical machines. These test are simple,
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How to Duplicate Xen DomU Virtual Machines

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Assumption: There are VBD based Xen DomU virtual machines stored under /home/xen/vm-f11-sample/. There are two files under vm-f11-sample: vm0-f11.run (The configuration file) and vmdisk0 (The virtual disk). Now we want to duplicate the virtual machine vm0 stored under vm-f11-sample to vm-10.0.0.213 which is stored under vm-10.0.0.213. And vm-10.0.0.213’s ip will be 10.0.0.213. The steps to
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