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HAProxy – High Availability Platform

lexo — Tue, 20 Jul 2010 15:42:53 +0000

HAProxy is a free, very fast and reliable solution offering high availability, load balancing, and proxying for TCP and HTTP-based applications. It is particularly suited for web sites crawling under very high loads while needing persistence or Layer7 processing.

HAProxy is known to reliably run on the following OS/Platforms :

* Linux 2.4 on x86, x86_64, Alpha, SPARC, MIPS, PARISC
* Linux 2.6 on x86, x86_64, ARM (ixp425), PPC64
* Solaris 8/9 on UltraSPARC 2 and 3
* Solaris 10 on Opteron and UltraSPARC
* FreeBSD 4.10 – 6.2 on x86
* OpenBSD 3.1 to -current on i386, amd64, macppc, alpha, sparc64 and VAX (check the ports)

Source:
http://haproxy.1wt.eu

GlusterFS

lexo — Thu, 13 May 2010 03:40:50 +0000

Gluster Storage Platform is an open source clustered storage solution. The software is a powerful and flexible solution that simplifies the task of managing unstructured file data whether you have a few terabytes of storage or multiple petabytes. Gluster Storage Platform integrates the file system, an operating system layer, and a web-based management interface and installer.

Source:
http://www.gluster.org

n2n: a Layer Two Peer-to-Peer VPN

lexo — Tue, 08 Dec 2009 21:15:55 +0000

n2n is a layer-two peer-to-peer virtual private network (VPN) which allows users to exploit features typical of P2P applications at network instead of application level. This means that users can gain native IP visibility (e.g. two PCs belonging to the same n2n network can ping each other) and be reachable with the same network IP address regardless of the network where they currently belong. In a nutshell, as OpenVPN moved SSL from application (e.g. used to implement the https protocol) to network protocol, n2n moves P2P from application to network level.

The main n2n design features are:

* An n2n is an encrypted layer two private network based on a P2P protocol.
* Encryption is performed on edge nodes using open protocols with user-defined encryption keys: you control your security without delegating it to companies as it happens with Skype or Hamachi.
* Each n2n user can simultaneously belong to multiple networks (a.k.a. communities).
* Ability to cross NAT and firewalls in the reverse traffic direction (i.e. from outside to inside) so that n2n nodes are reachable even if running on a private network. Firewalls no longer are an obstacle to direct communications at IP level.
* n2n networks are not meant to be self-contained, but it is possible to route traffic across n2n and non-n2n networks.

Source:
http://www.ntop.org/n2n/

Scribus – Open Source Desktop Publishing

lexo — Wed, 23 Sep 2009 19:27:28 +0000

Scribus is an Open Source program that brings award-winning professional page layout to Linux/UNIX, Mac OS X, OS/2 Warp 4/eComStation and Windows desktops with a combination of “press-ready” output and new approaches to page layout. Underneath the modern and user friendly interface, Scribus supports professional publishing features, such as CMYK color, separations, Spot Colors, ICC color management and versatile PDF creation.

Manual (Spanish) written by Antonio Cobo Cuevas, Profesor of informatics in I.E.S. Fuente de la Peña (jaen)

What’s shebang?

lexo — Tue, 22 Sep 2009 19:49:11 +0000

shebang/hashbang/haspling is…

#! <- The first two characters used in Unix-like in a script file, they're read by the program reader looking for the interpreter of this script, that is specified after the shebang. For example:

#! /bin/sh

Bandwidth limit

lexo — Sun, 21 Jun 2009 01:42:52 +0000

Some times we need to limit the traffic that uses some applications. In my case, when I download big files. So:

If we use wget, It is doted with –limit-rate option that permits set the limit of traffic.

Example:
# wget –limit-rate=50k http://lexo.lx-networks.net/testingfile.gz

This example limits wget to uses 50KBps maximum of download traffic.

But … ¿what’s up when we need use other application that it hasn’t the same option like this? Don’t worry, looking for it option I found a solution to do it.

trickle: is a portable lightweight userspace bandwidth shaper. It can run in collaborative mode (together with trickled) or in stand alone mode.

It works by taking advantage of the unix loader preloading. Essentially it provides, to the application, a new version of the functionality that is required to send and receive data through sockets. It then limits traffic based on delaying the sending and receiving of data over a socket. trickle runs entirely in userspace and does not require root privileges.

Example:
# trickle -s -d 120 -u 100 firefox

This example limits to firefox uses 120KBps for download and 100KBps for upload of traffic.

These are simple methods, because we can use traffic control at kernel level.