Category Archives: Networking

Network and Filesystem Isolation with LXC and virtenv

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For my memory comparison of light Linux desktops I needed a tool that would allow me to install on my computer about 20 window managers/desktop environments. After looking at several common virtualization packages, I ended up using Linux containers and virtenv for the job.

LXC and virtenv

Probably the best way to describe virtenv is as a graphic interface for Linux containers utilities developed and distributed by LXC project. Linux containers is the virtualization technology build into Linux kernel, available in any kernel after 2.6.32.

The virtual machines (VM) are driven without any overhead by the kernel already running on the computer. You don’t need to run a different kernel in the virtual machine, run only the processes you need, without even going trough the regular SysV or Linux init. This all means that memory is used very conservatively. For example, on a 1GB RAM computer you can run easily 10 SSH/DHCP servers, or 10 different xorg/X11 servers with LXDE window managers on top.

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SNMP MIB Browser on Ubuntu Workstation

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Updated on June 2, 2013

Ubuntu Linux is arguably the most popular Linux distribution today. Well designed and easy-to-use as a desktop, it is also an excellent choice for any kind of server infrastructure in datacenters. In fact, according to W3Tech, Ubuntu server is right now in the second position and growing fast as a webserver.

In a previous article I looked at installing a basic network router using RCP100 on a Ubuntu 12.04 computer. Today, I will take a look at using Ubuntu for some more serious SNMP work.

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RCP100 Basic Router Configuration on Ubuntu 12.04

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I do like the idea of an open-source software router, and I’ve tried several of them so far. Most open-source routers would concentrate on implementing the main IP routing protocols one by one. Administration features like CLI or SNMP seem to get less attention. There is little or no support for integrated Access Control Lists, NTP, DHCP or DNS functionality. This is in sharp contrast with the commercial routers where administration and network management are first class citizens.

RCP100 seems to break the tradition. It has a Cisco-like command line interface (CLI), and all the regular administration and management protocols. Starting with version 0.99 it also features a simple and intuitive web interface, making the router accessible to less sophisticated users and beginner administrators.

In this article I will set up a basic RCP100 IP router on a Ubuntu 12.04 computer using the web interface. This means there will be lots of pictures and no CLI commands. Networking experts will definitely get bored.

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Equal Cost Multipath

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Equal Cost Multipath (ECMP) is a network load-balancing method that enables the coexistence of multiple network paths form one source node to a destination node. The two or more paths between the nodes have the same routing cost, thus the traffic will be split evenly across, avoiding congestion and increasing the bandwidth.

ECMP is also a network redundancy method. In case one ECMP link fails, the traffic will move on the remaining links with minimal interruption in service.

For ECMP to work, a router will need special support in the forwarding plane and in the routing protocols deployed in the network. For experimentation I will use two Linux virtual machines on my host computer. The Linux kernel has an excellent ECMP implementation, as for the routing protocol I will use OSPF.

The virtual machines are set using virtenv. It is a very light virtualization solution based on Linux containers (LCX) implementation in Linux kernel. Each machine owns a slice of the Linux kernel running on the host computer, with full network and process separation. In each virtual machine I run one instance of RCP100. RCP100 is a router control plane for Linux platforms, supporting among other things OSPF and ECMP. RCP100 also features a CISCO-like command line interface (CLI) which simplifies router operation for people already skilled in configuring commercial routers.

The network diagram is as follows:

ECMP test network

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How to Speed Up Mozilla Firefox

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firefox logo

As the Internet goes slower and slower and your Internet Service Provider refuses to go faster and faster, these are three easy things you can do to speed up Mozilla Firefox:

1. Disable IPv6

For a regular web page such as slashdot.org, Firefox needs to resolve more than 40 domain names. Each domain name is resolved twice, once for an IPv4 address and once for an IPv6 address. This results in lots of DNS requests, slowing down your web access. If you are like 99.999% of the population without IPv6 access, translating domain names in IPv6 addresses is useless.

To disable this functionality, type about:config into the address bar. Type ipv6 into the search bar and toggle network.dns.disableIPv6 to true.

2. Install Adblock Plus extension

The extension will cut down most, if not all, advertisements and annoying banners.

3. Install Ghostery extension

The extension removes “invisible” trackers, web bugs, pixels, and beacons placed on web pages by Facebook, Google Analytics, and over 1,000 other ad networks.