Category Archives: Network

Testing Network And TCP Optimizations

This post is more like a “note to self” for certain TCP parameters which I usually modify (or plan to modify) on production servers.
Some good to know terms:

  • Round Trip Time (RTT): It is the time taken by a packet from source machine to reach destination and come back. You can use ICMP ping to get the RTT.
  • Latency: The time from the source sending a packet to the destination receiving it. This is often mixed with RTT. Clarify what you are talking about before interpreting anything.
  • Bandwidth Delay Product (BDP): It is the amount of data that can be in transit in the network or simply the product of link bandwidth and RTT.

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Filed under Network

Cloonix : Another userspace for KVM

Cloonix KVM is an alternative userspace for KVM designed specifically for simple realtime network topology management.  The killer feature of Cloonix is a GUI WYSIWYG tool that allows you to drag and drop elements in a network topology.  These elements include virtual machines, routers, LAN interfaces and sniffers among others. Networking uses a rewritten slirp userspace library so performance is not great but this is the tradeoff for the convenience of modifying your topology in real time in a graphical way.

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Filed under Network, Virtualization

SquidGuard Web Filter For Squid 3.x

How do I install and configure SquidGuard – a web filter plugin for Squid to restrict access to domains/URLs based upon access control lists? How do I block porn, gambling, and other web-sites using squid proxy server version 3.x under Debian or Ubuntu Linux server for my school ?

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Filed under How To, Network, Security

IPSEC VPN with Strongswan 5

This howto describes setting up an IPSEC VPN for use with the Iphone, Ipad and Mac OSX VPN clients on Centos/RHEL 6. I am using the 5.x branch of Strongswan which is now the mainline actively maintained branch. At the time of writing the 5.x EPEL package was only available in the testing repo.

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Filed under Apple, Network, Security

OpenLDAP Everywhere Reloaded

Directory services is one of the most interesting and crucial parts of computing today. They provide our account management, basic authentication, address books and a back-end repository for the configuration of many other important applications.

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Miredo : Teredo IPv6 tunneling

Miredo is an open-source Teredo IPv6 tunneling software, for Linux and the BSD operating systems. It includes functional implementations of all components of the Teredo specification (client, relay and server). It is meant to provide IPv6 connectivity even from behind NAT devices.

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IPSEC n2n VPN connections

This article takes a detailed look at the design principles, the basis for deploying VPN, and the IPSEC protocol concept, providing a description of the general features of IPSEC and of the mechanisms required for its implementation.

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Filed under How To, Network

Varnish HTTP Accelerator

An advanced Cache and very fast reverse-proxy system. Basically, Varnish handles serving static files and anonymous page-views for your site much faster and at higher volumes than Apache. It typically speeds up delivery with a factor of 300 – 1000x, depending on your architecture.

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Filed under Network, Performance

Virtual switching with Open vSwitch

Virtualization with Vmware, KVM, and Xen is here to stay. But up to now, no virtual switch has supported complex scenarios. Open vSwitch supports flows, VLANS, trunking, and port aggregation just like major league switches.

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About Host sFlow

The Host sFlow agent exports physical and virtual server performance metrics using the sFlow protocol. The agent provides scalable, multi-vendor, multi-OS performance monitoring with minimal impact on the systems being monitored.

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Openflow – Innovate in Your Network

OpenFlow enables networks to evolve, by giving a remote controller the power to modify the behavior of network devices, through a well-defined “forwarding instruction set”. The growing OpenFlow ecosystem now includes routers, switches, virtual switches, and access points from a range of vendors.

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Filed under Network, Uncategorized

MQ Telemetry Transport

MQTT is a machine-to-machine (M2M)/”Internet of Things” connectivity protocol. It was designed as an extremely lightweight publish/subscribe messaging transport. It is useful for connections with remote locations where a small code footprint is required and/or network bandwidth is at a premium.

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Use httperf for Server Benchmarking

When you’re prototyping Web applications or just trying to test and tune your Web servers, one of the best tools you can start with is httperf. The name probably gives it away, but httperf is a tool that generates workloads to test HTTP servers. It works with HTTP/1.0 and HTTP/1.1, as well as SSL if needed. It was written by David Mosberger for HP, and it is released under the GPLv2.

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Filed under Network, Performance, Utility

About Siege

Siege is an http load testing and benchmarking utility. It was designed to let web developers measure their code under duress, to see how it will stand up to load on the internet. Siege supports basic authentication, cookies, HTTP and HTTPS protocols. It lets its user hit a web server with a configurable number of simulated web browsers. Those browsers place the server “under siege.”

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Filed under Network, Performance, Utility

What is Balance ?

Balance is our surprisingly successful load balancing solution being a simple but powerful generic tcp proxy with round robin load balancing and failover mechanisms. Its behaviour can be controlled at runtime using a simple command line syntax.

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