SSH Port Forwarding on Linux

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Port forwarding (or tunnelling) is a method to forward one network traffic to another. We will introduce how to forward ports using SSH tunnel in this post. A simple example Let’s start with a simple and useful example: we want to forward local port 8080 to server:port. We can easily do this by using ssh
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How to Install ATI fglrx Driver on Fedora Linux

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Update on Nov. 18, 2012: ATI fglrx driver works well on Fedora 17 with GNOME 3 Shell. Should work well with later releases. Great driver, ATI! Update on Nov. 29, 2011: ATI fglrx driver works on Fedora 16 with GNOME 3 Shell with Catalyst driver 11.11 (xorg-x11-drv-catalyst-11.11). Update on Oct. 9, 2011: GNOME 3 shell
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Managing Xen Dom0′s CPU and Memory

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The performance of Xen’s Dom0 is important for the overall system. The disk and network drivers are running on Dom0. I/O intensive guests’ workloads may consume lots Dom0′s CPU cycles. The Linux kernel calculates various network related parameters based on the amount of memory at boot time. The kernel also allocate memory for storing memory
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Unified Linux Login and Home Using OpenLDAP and NFS

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In this post, how to unified Linux login and home directory using OpenLDAP and NFS/automount will be introduced. 0. System environment This solution is tested on Fedora 12 systems and CentOS 5. LDAP and NFS server: IP: 10.0.0.2 OS: Fedora 12 x86_64 ldap base dn: “dc=lgcpu1″ Clients: IP: 10.0.0.1/24 OS: Fedora 12 x86_64 1. LDAP
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Linux UDP Programming Tutorial

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UDP has its advantages over TCP, such as being relatively lightweight and receiving one packet per read call (recvmsg), although the programmers need to handle related issues, such as packet lost and out-of-order packets delivery. This post gives information and references on how to write UDP programs in a C/Linux environment. What is UDP Check
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How to Bypass Bad fstab Failure When Booting Linux

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If /etc/fstab file is created with errors or the hardware configuration changes such as adding hard disks, Linux will boot into failure state. We can bypass the fstab failure by adding booting parameters to Linux. We can do this in two methods: Method 1: Boot to single user mode When booting into single user mode,
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Changing Linux User Password in One Command Line

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In Linux, we use passwd to change password, but passwd requires input from stdin to get the new password. It is common case that we may want to change the password non-interactively, such as creating new user accounts and change or set password for these accounts on a number of Linux boxes when the new
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How to Enable root on Ubuntu

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For UNIX users/developers, having the power of the user 0 (root’s UID) on our hands is essential. It also allows us to have complete control over the system. And one more thing we all have in common is that we hate Windows. Thus, we set out in search of an operating system for our own
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How to Configure iOS to Use Socks Proxy over SSH with a Linux/Unix Host

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The socks proxy I created following Proxy Using SSH Tunnel works very well on both Linux and Windows. However, when I try to configure my iPhone and iPad with iOS, I find iOS does not support socks proxy in its settings interface. I don’t know why it is not added while socks proxy is indeed
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How to Copy Output of Commands in a Linux Terminal to X Selection or Clipboard

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xclip is a tool to copy the copy the output of commands from a command line in a terminal to X selection or clipboard. It connects the command line interface and the X selections (clipboard) and is a very useful tool. For example, processing some text in vim in a terminal and then copying it
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How To Mount Google Drive on Linux

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Google Drive is nice cloud storage which provide document editing features. However, it does not yet provide a Linux client. I find a good third party tool that works with Google Drive on Linux very well: google-drive-ocamlfuse. The website of google-drive-ocamlfuse provides easy to follow instructions to install it. In this tutorial, we show a
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Auto Keyboard Pressing Using xvkbd in Linux

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Automatic keyboard pressers are useful tools. However, it seems that there is no simple and easy to use automatic keyboard presser for Linux if you search for “automatic keyboard presser linux”. After some digging, I find using the xvkbd with some options is a good method for automatic keyboard pressing though it is not designed
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How to install no-ip client on Linux

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noip2 is a dynamic update client for No-IP to keep your current IP address synchronized with your No-IP domain, no matter whether the IP is dynamically requested via DHCP or static assigned. Furthermore, with the domain name, we can host site using a “static” domain whose CNAME points to the No-IP domain. noip2 is a
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How To Enable GNOME Classic Mode in Fedora / CentOS / RHEL Linux

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GNOME 3.8 introduces the classic mode: Classic mode is a new feature for those people who prefer a more traditional desktop experience. Built entirely from GNOME 3 technologies, it adds a number of features such as an application menu, a places menu and a window switcher along the bottom of the screen. Each of these
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Common Operations of Symbolic Links on Linux

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Symbolic link or soft link files are very common and useful on Linux/Unix systems. It works as a alias file for a file. You can create a symbolic links and it can operate transparently for most operations just as normal files. Programs that read or write to files named by a symbolic link behaves as
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Outlook-style Email Reply Header in Thunderbird

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Thunderbird’s email reply header is short and not like the ones in Outlook and other email clients. Thunderbird provides several integrated reply headers. However, the Outlook-style reply header with sender, receiver, date, and other information are clear and useful (e.g. my boss cc’ed an email to me to let me handle a request and I
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Floating Point in Bash Shell

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Integers are natively supported in Bash shell. However, what if we use floating point in Bash shell? The short and direct answer is using ‘bc‘ command – “An arbitrary precision calculator language.” Just run bc  and enter some floating point calculation expression, such as “1.2+8.2”, bc will give the result. In a script, we certainly
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Makefile Tutorials

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Make is a utility that automatically builds executable programs and libraries from source code by reading files called makefiles which specify how to derive the target program. Make is widely used, especially in Unix/Linux world. More introductions to Make and it’s history can be found on Wikipedia. In this post, I list articles for Makefile
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Inline Assembly with GCC on Linux

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One cool feature of gcc is that it can inline assembly into C code. With inline assembly, the programmer can precisely control the execution of the processor, such as forcing variables to use registers, getting special processor state efficiently, and writing critical efficient code in assembly by hand. I compile a list of tutorials from
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GNU C Reference Manual

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When we program in C, a C reference by hand is usually useful. The GNU C Reference Manual provides us a good reference for the C programming language implemented by the GNU C Compiler. “This manual is strictly a reference, not a tutorial. Its aim is to cover every linguistic construct in GNU C.” GNU
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