Linuxwarz
Technology Topics for Administrators
Welcome!
Mar 30th
Welcome to Linuxwarz.com
This blog is a collection of knowledge from the internet and books that I have had to put into production or lab use. My goal is to get my findings on search engines so that people needing to work on common topics can find the information without searching multiple websites. I try to publish a new article once per month. My content is geared towards Linux and Cisco topics, but I may expand past that every now and then.
About the Author
My name is Parker and I am a Cisco Certified Network Associate (CCNA) who is in the process of obtaining a CCNP. I have many years of experience using Linux in both hobbyist and web hosting provider settings. I believe Linux has very dynamic uses and I attempt to use it as a replacement for products that I would normally have to pay a premium for (Windows Server, Load Balancers, Enterprise Firewall/Routers).
Running Torrent Trackers: Not just for pirates anymore
May 12th
Torrents: Best known for grabbing illegal content from a massive amount of other people. Did you know that torrents and trackers can be used by content publishers as a high speed / low cost alternative to traditional HTTP distribution?
You may or may not have heard of Linuxwarz.com through The Orion Project. I currently provide Orion HTTP file distribution across three IPs, links, and two HTTPd servers. One of the issues small and large publishers face is the fact that bandwidth is always limited while the demand for files is always climbing from the end user. My link caps are currently 10/10/10mbit. Due to high speed internet being available all over the world, users are able to download at speeds well over 10mbit. This presents us with a unique problem, especially when distributing files in excess of 1GB to over 17,000 people in a few days. I can relate to downloading a large file, such as the hottest game beta, only to find out that I have to sit through advertisements and a 10min wait to even start the download. To make matters worse, the download is crawling at 100kb/s when my ISP connection supports 2.0mb/s. All sorts of problems arise when using an HTTP distribution model. Slow downloads, long wait times, and the potential for a large download to be interrupted by a connection loss. I will explain how a content publisher can utilize a tracker, torrents, and web seeds to fix all of the problems of traditional HTTP.
Quick Reference: Using traffic control (tc) to throttle traffic per TCP/UDP port
Apr 22nd
Problem
Having a particular application hog the network resources on an already limited connection is a bother. Picture yourself on a 10mbit link while running an HTTPd server that serves mirrored files. This is a high bandwidth application that could very well be maxing out your 10mbit link 24/7/365. I tend to find that link utilization over 80-85% causes issues with more sensitive applications such as SSHd. You might be asking yourself: “How do I throttle the connection so that HTTPd does not choke other applications?”. You might also be aware of tc but find it is too complex to learn in a short time frame.
Solution
I will show you how you can leverage the power and control that tc provides in a simple to understand summary. Please note that I might be writing about more advanced tc topics in the future and that this guide will get you started with simple per TCP/UDP traffic throttling.
Quick Reference: Using vlans with Linux
Mar 31st
Problem
Using a Linux host to communicate to multiple subnets through a vlan trunk. The most common reasons you might want communication with all vlans are to either route between them while keeping a firewall up to restrict access or to provide all of them the same service (ntpd, dhcpd, httpd) without having the ability of each vlan to communicate with one another.
Solution
Linux supports IEEE 802.1q through a kernel module and an application. The process to get vlans configured is a pretty simple process.
More >
HOWTO: Using Linux as a simple load balancer / nat router / firewall
Mar 28th
Problem:
Creating a simple network load balancer and router using Linux while maintaining redundancy for a mission critical network.
While on the job at a local cyber cafe, the owner came up to me and asked for a solution that would allow him to stop using expensive (and slow) T1 lines while giving him the option to balance between up to five cable (coax) links.
My research lead me to a low cost solution: utilize old hardware with Linux in a redundant setup. I created multiple scripts and configuration files which enabled Linux to not only load balance with a round robin configuration, but provide the proper connection and firewall support that was needed. The following guide will enable you to setup Gentoo Linux to perform balancing; but the instructions are compatible on most distributions with little or no tweaking.
Solution:
Utilize the Linux operating systems existing kernel modules and settings in conjunction with iproute2, iptables, and VRRP to allow routing and round-robin load balancing.
HOWTO: Two ethernet links using the same subnet / vlan in Linux
Feb 2nd
Problem
An uncommon scenario in the hosting world is when you might need something along the lines of 20mbit bandwidth but the ISP only offers 10mbit per physical line.
You might also want two interfaces on the same vlan that are not bonded for various reasons as well.
