Tech Tips » Networking

Change your Network card MAC ( Media Access Control) address Using macchanger

chandu — Tue, 09 Jan 2007 04:17:07 +0000

Media Access Control address, a hardware address that uniquely identifies each node of a network. In IEEE 802 networks, the Data Link Control (DLC) layer of the OSI Reference Model is divided into two sublayers: the Logical Link Control (LLC) layer and the Media Access Control (MAC) layer. The MAC layer interfaces directly with the [...]

Change your Network card MAC ( Media Access Control) address Using macchanger

Originally from ArsGeek by david23

How to set up a DNS Server using Bind

chandu — Tue, 02 Jan 2007 06:21:06 +0000

The Ubuntu Document Storage Facility has a good article on setting up a DNS server using Bind.
You can read the original here or check it out below the jump.
After looking on Ubuntu forum for an easy step-by-step howto for instaling a DNS server, I decided the best idea would probably be to write this howto [...]

How to set up a DNS Server using Bind

Originally from ArsGeek by arsgeek

VNC Navigator – Manage your VNC Servers Easily

chandu — Fri, 20 Oct 2006 06:12:36 +0000

�VNC Navigator allows you to easily manage your VNC connections. Quickly connect to VNC Servers, and store passwords in an encrypted database�

VNC Navigator is a remote administration tool to help you easily manage your VNC servers. Currently this VNC Navigator supports the most famous versions VNC such as RealVNC, TightVNC and UltraVNC.

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VNC Navigator – Manage your VNC Servers Easily

Originally from AdGlobe Tech Blog by noemail@noemail.org (carolyn)

How to tunnel with SSH – Secure Windows to UNIX or Linux connectivity

chandu — Thu, 19 Oct 2006 06:43:53 +0000

Learn how to tunnel with ssh, to get Windows to UNIX connectivity in a secure world. With new security threats cropping up every day, network managers are understandably protective of their computing assets. Enhanced security measures, however, can inflict significant hardships on legitimate users and can lead to frustration, productivity losses, and dangerous attempts at circumvention of restrictions. Equipping yourself with proper tools for connectivity can make your tasks easier while still maintaining network security and integrity. One of the most valuable tools in the IT toolkit is Secure Shell (SSH).

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How to tunnel with SSH – Secure Windows to UNIX or Linux connectivity

Originally from nixCraft by nixcraft

TightVNC – Free Remote Control Tool

chandu — Thu, 19 Oct 2006 06:38:50 +0000

TightVNC is a free, cross-platform remote control software package derived from the popular VNC software. VNC stand for Vitual Network Computing which allow remotely view and fully-interact with one computer from any other computer or mobile device anywhere on the Internet. TightVNC includes better compression algorithms for improved performance over WAN links, as well as new features like automatic SSH tunneling between Unix/Linux hosts. It is designed to work over slow connections.

For more info about TightVNC�s features: http://www.tightvnc.com/intro.html

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TightVNC – Free Remote Control Tool

Originally from AdGlobe Tech Blog by noemail@noemail.org (carolyn)

Understand IPv6 Addresses

chandu — Thu, 28 Sep 2006 13:00:22 +0000

For general knowledge on what IPv6 has to offer the following article is not a bad one.
In the olden days, it was possible to skate over understanding the binary math behind IPv4 addresses by memorizing the various classes and their address ranges. That won’t work for IPv6. Get yourself an IP address calculator and learn [...]

Understand IPv6 Addresses

Originally from Linux and Open Source Blog by E@zyVG

How to stream videos in lan and internet.

chandu — Mon, 04 Sep 2006 10:06:37 +0000

Quadmaster posted a nice guide to streaming video in lan on the techenclave website. All you need is the great media player VLC (video lan client), in a recent poll 36% of all voters on ghacks voted for vlc as the best media player. You need to assign local IP addresses if you have not done so allready, for sake of simplicity I assume the main pc that streams the content has a IP of 196.168.0.1 and the first client pc that recieves the stream has the IP 192.168.0.2.
[More in the below article...]

How to stream videos in lan and internet.

Originally from gHacks tech news by Martin

Secure User to User Communication

chandu — Thu, 31 Aug 2006 06:10:05 +0000

CSpace is a freeware that offers its users the possibility to securely communicate over the internet using public RSA keys with a strength of 2048 bit. Every user creates a 2048 bit RSA key for himself and maintains a contact list of names associated to public keys of other users. Public keys are exchanged using a key server. Cspace users can chat with each other, transfer files and even use a remote desktop feature.

Secure User to User Communication

Originally from gHacks tech news by Martin

Mirror files across systems with rsync

chandu — Thu, 24 Aug 2006 15:19:10 +0000

Nice writeup on using rsync to mirror files across a variety of operating systems: rsync – Lifehacker

Mirror files across systems with rsync

Originally from StanShinn.com by Stan Shinn

A brief look into P2P BitTorrent networks

chandu — Sun, 20 Aug 2006 02:46:42 +0000

As part of the research for a new product, I took a look at some existing P2P networks, specifically those networks using the BitTorrent technology. The entry below will provide you with a basic understanding of what you need in order to access and use existing P2P BitTorrent networks.

Safeguarding the test system

Before I got my hands dirty, I dug out my old PowerBook G4 laptop and created a new user account without system administration rights. I wanted to contain the risks to a computer that can be easily re-formatted, and to an account that has no personal data.

What is it?

What’s BitTorrent? From Wikipedia: BitTorrent is the name of a peer-to-peer (P2P) file distribution client application, its related file sharing protocol, and a company that maintains these, BitTorrent Inc., all of which were created by programmer Bram Cohen. BitTorrent is designed to distribute large amounts of data widely without incurring the corresponding consumption in costly server and bandwidth resources.

Clients

There are various clients for the Mac, but I only looked at three different one during my research.

BitTorrent

Azureus

Transmission

Installation of the programs is simple, but configuration of your network requires expert knowledge beyond the average computer user. The instructions in one of the programs said it best: “BitTorrent clients work best when running completely open to the Internet.” Great advice! – NOT! While I am sure this is true as far as the BitTorrent client is concerned, it would not be wise to leave your PC directly connected to the internet without a router/firewall in place.

My home computers all run a software firewall, and they all sit behind a router with its own additional firewall. To make my little experiment work, I had to

Assign a fix IP address to my PowerBook G4
Open a port for UDP and DHT on my router and forward it to my G4 IP Address
Tell the BitTorrent client which port number to use for its outside connection

Not a process that most computer users would feel conformable following.

Where is all of the content?

When it was all done, I had a client ready to receive or send files, but no list of files to download.

Off I went to ISOHunt and TorrentSpy to search for some content.

Note: a lot of the content on torrent sites are copyrighted materials. I do not copy nor use copyrighted content of any kind (music, video, movies, software, etc…).

After I found what I was looking for it came the long process to download the file. While BitTorrent technology is intended to make the download fast, I was only able to achieve a maximum speed of 60 kB/s, often much lowers . As a result, most of my downloads and uploads would take several hours, and even days to complete. Not a great user experience.

Usability wise, these clients are made for geeks, and intended to be used by geeks. Seeds, Peers, Swarm, Hash, Tracker, NAT, Vivaldi, Cache are all terms that are prominently featured in the UI. It makes it fascinating to watch if you a technology guy, but completely over-whelming and complicated for ordinary folks.

I got the file, now what?

Once the file was eventually downloaded I needed to figure out a proper way to play it. Many files were RAR encoded, which required an additional software to

decode it. You can use Gumby, UnRarX, StuffIt to properly unpack the file. In my case, about 20% of my downloads where corrupted and would refuse to unpack – major bummer after waiting multiple hours for the download to complete.

Once the file is unpacked, you will most likely need a new video player, or at least new codecs, to be able to play the file. To play most video files on my Mac, I use VLC, a great open source, multiple format video player (MPEG, MPEG-2, MPEG-4, DivX, mp3, ogg, AVI, DVD, VCD, …)

Ironically, many of the downloaded files are intended for you to burn them to a CD or DVD. I don’t know about you, but we are moving almost exclusively to a digital world in our house, and we are quickly abandoning all physical media. The thought of downloading a file on my Mac only to burn it back to a DVD to play it on a TV is arcane and backwards.

If you do want to burn the file back to a physical media, you need to use Roxio Toast – in this case, a commercial software.

Overall Quality

The quality for most of the files that I tried was very poor, even though they were rated high by the community at large. Those people who have complained about iTunes TV show quality haven’t really played around with Torrent files that much, iTunes videos are much better than the 10 different files I tried – your results may vary.

Overall, my early look into BitTorrent networks has proven frustrating, with poor quality content, even fewer legal content, a high technical barrier to entry, and an overall disconnected process involving multiple clients/tools/web sites in order to be experienced end-to-end.

For now at least, BitTorrent networks are the domains of the technology geeks; much must be done before this technology can be productized and used by regular computer users with any degree of success.

A brief look into P2P BitTorrent networks

Originally from Applepie by Cris

SmartSniff, a smarter packet sniffer than Ethereal/Wireshark

chandu — Sun, 20 Aug 2006 02:42:25 +0000

Last Friday I posted a list of free packet sniffers. There, I promised to write about my favorite tool. You might have guessed that it is Ethereal since it probably is the most popular free network packet sniffer. It has many feature which its free rivals lack. This is also true for the free sniffer [...]

SmartSniff, a smarter packet sniffer than Ethereal/Wireshark

Originally from 4sysops by Michael

Free packet sniffers for Windows

chandu — Sun, 20 Aug 2006 02:42:20 +0000

A packet sniffer is used to analyze the network traffic. Sometimes they are also called network analyzers, protocol analyzers or ethernet sniffers. System administrators usually use them to analyze the behavior of an application or device causing network problems. I made a list of free packet sniffer tools for Windows. The descriptions are taken from [...]

Free packet sniffers for Windows

Originally from 4sysops by Michael

OmniPeek Personal – free network monitor, better than Wireshark

chandu — Sun, 20 Aug 2006 02:23:54 +0000

WildPackets Omnipeek Personal is a free network monitoring tool for personal use. The .Net 2.0 tool has many features which most free packet sniffers/packet analyzers lack, especially when it comes to statistical analysis and visualization. Omnipeek is even better than Ethereal/Wireshark.
However, the personal version of Omnipeek has two limitations compared to the commercial version. [...]

OmniPeek Personal – free network monitor, better than Wireshark

Originally from 4sysops by Michael

Scheduling your FTP downloads

chandu — Sun, 13 Aug 2006 09:00:40 +0000

Recently I had the need to download from my company’s servers some files on daily basis. I had to replicate some data at my home server (I work from my home cause as I said on “About“, I can’t stand Athens). The operation normally takes a couple of hours on my 1Mb ADSL connection, so I had to do it only at night, while I was sleeping. Unfortunately, many times I forgot it and I had to do the FTP transfer at the morning waiting and bottlenecking my connection. Then I found this freeware software called FTP Scheduler…

FTP Scheduler offers automated scheduled downloads from FTP servers. It supports passive mode and manual mode and can download files based on wildcards or entire remote directories. You can schedule it at a specified time or on recurring times (e.g every 60 minutes). The files will be downloaded to a specified folder and all transactions are logged. Also supports command line options. Runs in the system tray.

Download FTP Scheduler >>>

Scheduling your FTP downloads

Originally from 10 daily things by djstelios

chandu — Sun, 13 Aug 2006 01:51:06 +0000

J2ME VNC is an open source mobile software that allows you to remotely access your desktop computer with any VNC compatible software installed on it from your mobile phone (Symbian or some Windows Mobile devices) which supports J2ME (Java 2 Micro Edition). You can then control the mouse and keyboard of your desktop computer and perform actions on it.

This app now supports SSH2 and HTTP tunnelling. SSH2 would require an MIDP 2.0 compatible phone. (Yeah, the older Nokia phones won’t work )

The site doesn’t have an FAQ so I am just pasting it off a forum post:

Connect: Connect to the server
Add: Add the current details (host & password) to the quick-access menu (warning: saved as plain text in your phone!)
Manage: Delete items in your quick-menu.

The host and password should be faily obvious, a host name, and the password to access the host.

Note: It is important to put the server name in the IP Address/Host Name:Port Number (what you selected in the VNC program on the desktop) format
e.g 10.120.125.15:5879

You then get the “Connecting” screen, after this you are presented with a small section of the screen of the server, and have the following commands:

Exit: Exits the application
Refresh: Refreshes the current screen.
Call Mouse: Centers the mouse on the currently vistable section.
Enter Text: Creates a text box to enter text in your phones default method (123abc normally)
Toggle Control: holds the control key up or down
Toggle Alt: holds Alt the key up or down
Toggle Meta: holds the meta key up or down
Mode: Lets you select the
view mode, either Normal (the default) or “Full Screen” were it shrinks the servers screen to fit the device.
and Entry Mode:
Navigation: The Curser keys move the screen, and the number keys act as number keys (press 1, one is sent)
Mouse Mode: The Curser keys move the Mouse Pointer, and the number keys act as number keys (press 1, one is sent)
SMS Mode: The Curser keys move the screen, and the number keys act kind-of like SMS entry keys ( 1 onces gives 1, seconds time A, then B then C, etc).
Options:
You have three options, how fast you wish to scroll left/right or up/down, and the “Active Refresh”, which will refresh the screen every 3 seconds.