NSA: Please Turn off the Lights When You Leave. Nothing to See Here.

Linux Advocate Dietrich Schmitz shows how the general public can take action to truly protect their privacy using GnuPG with Evolution email. Read the details.

Mailvelope for Chrome: PGP Encrypted Email Made Easy

Linux Advocate Dietrich Schmitz officially endorses what he deems is a truly secure, easy to use PGP email encryption program. Read the details.

Step off Microsoft's License Treadmill to FOSS Linux

Linux Advocate Dietrich Schmitz reminds CIOs that XP Desktops destined for MS end of life support can be reprovisioned with FOSS Linux to run like brand new. Read how.

Bitcoin is NOT Money -- it's a Commodity

Linux Advocate shares news that the U.S. Treasury will treat Bitcoin as a Commodity 'Investment'. Read the details.

Google Drive Gets a Failing Grade on Privacy Protection

Linux Advocate Dietrich Schmitz puts out a public service privacy warning. Google Drive gets a failing grade on protecting your privacy.

Email: A Fundamentally Broken System

Email needs an overhaul. Privacy must be integrated.

Opinion

Cookie Cutter Distros Don't Cut It

Opinion

The 'Linux Inside' Stigma - It's real and it's a problem.

U.S. Patent and Trademark Office Turn a Deaf Ear

Linux Advocate Dietrich Schmitz reminds readers of a long ago failed petition by Mathematician Prof. Donald Knuth for stopping issuance of Software Patents.

Showing posts with label Virtual Network Computing. Show all posts
Showing posts with label Virtual Network Computing. Show all posts

Monday, June 10, 2013

A small problem and some solutions


by Tracyanne

A couple of weeks ago my primary computer's video card died, it had been displaying signs that it was on the out for a while, but it finally gave up the ghost and refused to display anything intelligible, so now it's in the workshop waiting for a new card to arrive from Taiwan.

In the mean time I've resurrected my partners old laptop and installed the hard drive from my machine into it. This required that I reinstall the OS as my machine is 64 bit , and this machine is 32 bit. However there are a few small problems, the display on my partner's old machine has missing pixels and a few missing keys, and the sound doesn't seem to work.

My initial solution to this problem was to use my net book connected to an external monitor and accessing the other machine via X over SSH. In that manner I have a fully functional keyboard and can view the desktop on a large high resolution monitor (1920x1080).

When using X over SSH my desktop looks like this:
With the net book's panel at the bottom and the panel from the other computer's desktop at the top. I'm running Ubuntu Studio with LXDE on the net book and Linux Mint KDE 32 bit on my partner's old machine, but I've installed XFCE panel for this exercise. The email client's GUI is being accessed over the network.

I've was told that VNC is faster than X over SSH, so I decided to try VNC. For my purposes it's not necessary to tunnel VNC over SSH, as it is all operating over my LAN, so I haven't bothered with that set up.

I installed several different VNC servers and clients, until I found a combination that I was happy with. With the server running on the other computer and the client running on my net book.

My desktop looks like this:


This is the desktop of the other computer, the VNC client is set to display at full screen with a resolution of 1920x1050 (on 1920x1080 resolution monitor). To access the desktop of the net book I have to run the VNC client at a smaller resolution, and not utilise full screen in the VNC client.

From my perspective, there are a few issues with VNC.

  1. I can't use VNC at full screen, if I want to also access the desktop of the net book.
  2. I'm not seeing any performance gains, over my LAN, and the display shows obvious refresh activity, which leads me to believe displaying a full desktop over a network may actually be slower than displaying the content of a single window, as X over SSH does.
  3. I have noticed that one or the other of the two machines, appears to lose connection with the Wireless LAN, often enough that it causes problems for both X over SSH and VNC, with the problem magnified by the need to refresh the display in the client periodically, when using VNC.

Based on my experiences with VNC and X over SSH, I think I prefer X over SSH, it seems to recover from the momentary drop outs better than VNC. However, neither seems to provide me with the elegant solution I am looking for.

I remembered another potential solution to my problem, and after some searches on the Internet rediscovered Synergy - http://synergy-foss.org/.

Synergy is an application that enables Mouse and Keyboard sharing between several computers over a network. It it cross platform, so runs on Linux, Mac and Windows. The only potential drawback is that each of those computers must have it's own monitor. Fortunately I have a spare monitor with 1680x1050 capability, which I set up on my desk so that I have 2 monitors, one above the other, with the 1920x1080 monitor connected to my net book on top.

I installed Synergy 1.3.8, but this version proved to be very buggy,. Every time I used a Control key, such as SHIFT or CTRL while I was using the client machine, the synergy client would crash, and I would have to restart it after physically attaching a mouse and keyboard to the machine. Running the 1.3.8 version of Synergy client as a daemon with –restart enabled made no difference.

After some more Internet research I discovered that there is a fixed version of Synergy 1.4.10 available in the Ubuntu 12.04 (Precise Pangolin) backports, so I upgraded both the server (my net book) and the client machine to Synergy 1.4.10. Now it works correctly and I can use the Control keys.


My Desktop looks something like this:

Top Monitor:




Bottom Monitor:


This set up works quite well, although if I shut down the client machine I do have to move the keyboard connector (USB) to a USB port on it, in order to Log In.

The Synergy client starts Automatically on start up. I added the command

synergyc --restart --daemon brenda

to Session and startup. As does the Synergy Server with

synergys -c /home/tracy/.synergy/synergy.conf

added to Session and Startup on the server machine (my net book).

This arrangement works very well for my purposes. The only other issue I had was accessing files on the client machine. This I achieved using SSHFS on the server to access the client machine's file system over SSH. I had been doing this when using X over SSH.

It looks something like this:
 
I will most likely connect the two machines via ethernet, as there are still drop outs occasionally (most likely the net book). Though they do not appear to affect the stability of the system.


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Tuesday, March 19, 2013

Linux Systems Administrator Tools to Die For

by Dietrich Schmitz

You are the 'go-to' Linux Systems Administrator for your organization.

The fact is, you have a lot to do and there are only so many hours in a day.  So, you are always looking for new ways to leverage the use of your time.

Here is a list of popular tools which should be in every Admin's toolbox that provide time-saving functions and features that will help in all manner of troubleshooting and problem-solving situations.

Nmap/Zenmap


Nmap is one of those tools that simply cannot be overlooked and will save hours of guess work when troubleshooting a network.  Used to discover hosts and services on a network from the command line an accompanying graphical package can be installed, called ZenMap.

Command Line Utilities

These command line tools are some of the most commonly-used system utility programs for every-day system administration.  To get help, read the respective man page for each.

ssh, screen, vim, awk, sed, Perl, Netcat, Nslookup, ping, whois, traceroute, Netstat, dig, dd, tcpdump, rsync

WireShark

Wireshark is an open source packet analyzer.  It is simply indispensable when it comes to troubleshooting network connections and provides visualization in a Gtk graphical display of every minutiae for the protocol being traced.

BitDefender System Rescue CD


System Rescue CD provides a Live bootable CD for performing Anti-Virus scanning of any volume.  It's advantage comes from being able to bootstrap (pen drive or CD) into Linux on a Windows PC and scan the Windows NTFS drive partition for virus detection off-line.  Doing a full scan off-line ensures the persistent signature of a virus will be detected.  Quite often, Viruses evade detection by on-line Windows AV software, so this is a good security tool to have for a network having both Windows and Linux PCs.

Virtual Network Computing (VNC)

VNC, was released as open source and licensed under GPL.  It has several derivative versions, including RealVNC, TightVNC, UltraVNC, all of which allow remote desktop access and control over a network.  This free tool is popular for performing IT support in an organization for obvious reasons.


FreeNX


FreeNX is a subset of the commercial NX thin client protocol for remote desktop computing.  FreeNX is open source and licensed under GPL and offers free NX-based thin client terminal access to a Linux Server.  NX has programming optimizations which reduce the amount of X Windows metadata semantics which must travel across a connection by only sending the 'delta' portion of a screen change.  This effectively results in near-local machine performance over long distances and even on low-bandwith 56K dial-up connections. NX by default is secured and running over a tunnel-encrypted secure shell (ssh) connection.

OpenVPN


OpenVPN is an open source GPL licensed Virtual Private Network (VPN) solution.  Linux NetworkManager plugin architecture provides an OpenVPN module for easily setting up Client PCs with access to a corporate-firewalled VPN private subnet.  VPNs by default expose both TCP and UDP port ranges for all ip-ranges defined in the OpenVPN configuration.  This effectively means a remote PC can see and use all corporate resources while tunneled over a VPN secure encrypted connection the same way as a locally connected PC.

Chrome Remote Desktop


Popular Google Chrome web browser has become an indispensable tool for so many reasons.  One need only visit Google's Chrome Web Store to see the array of applications and plug-in extensions available for download.

Among these extensions is found Chrome Remote Desktop.  Chrome Remote has become a popular easy way to provide remote PC assistance.  It is free and the only requirement is that both end-point PCs be running Chrome with the Chrome Remote extension loaded.  Chrome Remote doesn't require special firewall pass-through rules and uses it's own Google server tunnel encrypted protocol (middle-man) to bridge across any firewall for unimpeded access.

Kernel-based Virtual Machine (KVM)


Kernel-based Virtual Machine (KVM) is built into the Linux Kernel and free.  KVM is a type 1 hypervisor providing 'bare metal' performance and is competitive with other Virtual Machine host software vendors such as Citrix ZenHost, VMware, ProxMox, and most recent Linux Containers (LXC).

Virtual Machines offer many benefits not the least of which is quick deployment of servers as resource loads on a VM host without the need to procure additional server hardware.  All hardware is emulated in the virtual machine.  Many IT shops are trending with collapsing down racks upon racks of rack servers into a consolidated high-performance host virtual machine 'farm'.  The multi-core VM host handles the processor overhead of the former bare-metal hardware based processors transparently, reduces power consumption, increases 'high availability' (little or no down-time).  These features increasingly make transitioning to virtual machines a 'hot' technology, and a very competitive one.  Knowing a modicum about KVM will give the Linux System Administrator a sharp technical edge and automatic advantage in today's cost-cutting tight-budget IT environments.

SELinux/AppArmor

SELinux, a Linux Security Module (LSM) is at the very core of Linux's security design, originally developed with assistance from the National Security Agency.  SELinux essentially defines Mandatory Access Control for each application running in its sandbox.  Applications must adhere to a profile of expected or allowed normal behaviors and any deviation from those policies is automatically undefined and will be rejected by the SELinux kernel module.  The Mandatory Access Control is quite effective and you will find SELinux present in Red Hat Linux, Fedora Linux, and an LSM called AppArmor running by default in Ubuntu Linux.  Learning either SELinux or AppArmor is an imperative for today's Linux System Administrator to gain a competitive advantage in the IT job market.

Samba

Samba is an open source free software application which re-implements the  SMB/CIFS networking protocol for sharing files across a network.  SAMBA4, recently released, now includes support for acting as a wholesale replacement for a Windows Active Directory Primary Domain Controller (PDC).

If you watch technology trends as closely as I do, you will realize the implications of Samba4 are quite big.  Already there are Samba PDC stack vendors competing to sell Windows AD PDC implementations replacing Windows Hardware and unencumbering buyers of Windows Licensing restrictions and cost.  Learn as much as you can about Samba.  You'll definitely score high the more you know and IT retention usually takes into consideration those who have the most important skills.  Catch my drift? ;)


Nagios System Monitor


Nagios may not be the newest System Monitor on the block, but, still, its reputation precedes it.  That means its deployment will greatly lower some of the inherent risks that every IT department faces.  Nagios when properly configured will monitor your entire network of services and based on its rule set notify you if/when a service goes down.  That can keep your down-time vulnerability to just minutes when you are sitting at home and get an SMS text message that one of your servers is off-line.  Quickly responding from anywhere with remote corrective action might mean that no one will even know there was an issue or you will have a chance to act before reaching work on a Monday as opposed to having a down system during production hours--an IT manager's worst nightmare.  It's just good business practice in today's world to set up and configure a system monitor for your IT shop.  It will pay over and over for itself.  I promise.

Clonezilla


You know, in the proprietary software world, you can spend a lot of IT dollars without blinking an eye.  Every time you turn around Symantec has another License renewal that must be paid for.

Ghosting machines doesn't have to cost money.  In fact, Clonezilla does everything Symantec Ghost does for free.  So if you pre-image your PCs using Ghost, switch to Clonezilla and get those software license IT dollars back into the budget by doing the job for free.  This is another cutting edge skill you will want to get under your belt.

So, that's it.  I think that covers the range of skills areas over which a Linux System Administrator will want to have maximal efficient control.  Stay smart.  Use the 'best of breed' tools you can find and run a tight IT shop with open source Linux tools 'to die for'.

-- Dietrich



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