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Lan Network

Lan Network
Lan Network

Testing network applications using network emulators

A networked application is any application that intrinsically uses a network as part of its operation, e.g. web based applications, networked database access, file transfer programs, mail transfer programs, messaging protocols, streaming voice, video, radio etc. It does not include applications like MS Word, unless of course a file needs to be opened on a remote file share.

These networked applications are now core to many of the things every computer user does every day – simple things like accessing bank accounts online, accessing emails & calendars, booking travel tickets, social networking, (Facebook), and smart phone applications. They also can be found in processes such as controlling traffic lights and operating modern IP based public CCTV.

There is a whole world of difference between how an application runs in the LAN and how it runs in the WAN, Satellite, Mobile 3G/GPRS etc., which cannot be simply resolved by increasing the available bandwidth.

For example, a file copy that takes 8 seconds to download in a LAN could take 75 seconds in a typical WAN/Internet link covering a distance of 165 miles even when both LAN and WAN have a bandwidth of 100Mbps. Even where available bandwidth is not a problem, ‘latency’ issues can really impact on performance particularly if an application is ‘chatty’ and needs lots of “acknowledgements” during transmission.

Having a way to experience how applications under development will perform when placed in the real network prior to actual roll out will become even more crucial going forwards. Developers will need to know that they are creating software that can cope well with the challenges of being delivered over “unfriendly” networks to avoid wasting time in retrospective rewrites and fixes.

Understanding Network Conditions

Networked applications will, at some point, experience a myriad of conditions as they travel over networks such as WAN, Home Cable, (A)DSL networks, and satellite networks, Wireless networks including GPRS, 3G, and WiMAX or LTE. Conditions that an application will experience will depend on the type of network but intrinsic to all are characteristics that are “unfriendly” such as latency, error, loss, jitter, insufficient bandwidth etc.
The best approach to overcome these problems is to get the development right by experiencing how an application will perform in these non-LAN networks during the development and test processes, but without using the live network.

Network emulators will allow the developer to re-create any of these difficult and complex networks in prototyping & development environments, and in test environments. They eliminate the need for the use of miles of cable, aerial masks, satellite dishes, mobile phone handsets etc. or using your corporate network in order to conduct realistic testing.

About the Author

Submitted by Phil Bull from iTrinegy, developers of sophisticated, yet easy-to-use, application performance monitoring, network emulation and WAN optimization technology to help organizations address networked application performance issues, de-risk application roll-outs and optimize network utilization.

How to prevent unauthorised laptops from accessing my wired lan network ?

How do I prevent unauthorised laptops from accessing the wired lan network – the wired lan network has about 10 machines on it – 9 desktops and 1 laptop. I want to prevent unauthorised laptops from plugging in physically to the network – by removing the CAT 5 cable and plugging in the same to the laptop – and then accessing information on the entire network.

The best way to protect your network is to use explicit access control based on Media Access Control (MAC) addresses that a uniquely identify each network interface. Most broadband routers have such access control feature readily available, but the degree of simplicity to configure and enable them depends on make/model and firmware revision of the router. You’ll need to consult the documentation for specific instructions for “Access Control” and/or “MAC Filtering” for wired and wireless services.

Securing the wireless portion will be relatively easy: Choose the most advanced algorithm and the longest encryption key possible. WPS is the latest and simplest technology (pretty much all systems made in the last 2 years support it), followed by WPA2 and WAP (which has 1 known vulnerability that occurs only in 1 specific type of configuration). Avoid WEP – it’s relatively easy to crack (but it’s better than nothing, as outlined in the article “Securing your wireless network” listed in the sources below).

I would suggest the following measures:

1.Change the administrator password to a non-default password.
2.Don’t broadcast your SSID (so it won’t show up in a network list).
3.Change channel from default (unless your router is capable of sensing conflicts).
4.Reduce your Wifi transmitting power (reduce the area of coverage to a minimum).
5.Use MAC filtering for access control.
6.Use the most sophisticated encryption available.
7.Use a non-default IP address range (e.g. 192.168.121.x or 192.168.137.x is better than 192.168.0.x or 192.168.1.x because these ranges are harder to guess)

For the wired ports, things are a bit more complicated (and again depend on make/model and firmware revision of your router and switches): There is usually less security on wired connections because of historical evolution and an assumption that physical access can be limited to trusted people. So, let’s start with physical access: Put all routers, switches and modems into a lockable room (or a lockable cabinet with sufficient ventilation). Try to protect CPUs and wall outlets so that there is no easy access (i.e. expose only keyboard mouse and monitor and hide the CPU and network connections in cabinets).

If you cannot physically protect the network connections (i.e. somebody can unplug a cable either at the computer or a wall outlet), you can implement some logical measures but these are somewhat limited with consumer-level hardware (because of costs and the fact that such devices are meant to enable access rather than prevent it). In some cases, routers also apply the above mentioned MAC filtering rules to wired connections. This would be your first line of defense.

However, on hubs and simple Ethernet switches, the data traveling on the wires can be seen by all devices on the network. This makes it relatively easy for a cracker to install a packet sniffer, look into the traffi and learn what devices are attached. The cracker then can configure his or her system to pretend it was a legitimate system – a process that is called “spoofing.” That’s why in high-security environments use more sophisticated ethernet switches (for example the Cisco 3550 series) that enable and disable physical ports and authenticate attached systems and their users based on access control systems like Tacacs+ or Radius. Taking advantage of such features requires authentication servers and software installed on the client systems that deal with the challenge/response mechanisms (additional hardware and software = additional costs).

Security is a trade-off based on a cost/benefit analysis (how much security do you need and how much time and money are you willing to spend on implementing and maintaining it compared to how much you could actually lose in terms of stolen data or stolen services). By the same token, cracking networks is also subject to a cost/benefit analysis: How much time and effort is a cracker willing to spend to intrude a network.

At the end of the day, no security measure is perfect and all networks can be cracked. It’s sensible to protect yourself by setting the bar as high as possible. So, I hope my answer provides you with some insights and guidelines for securing your network as good as possible with what you already have.

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The Plugable USB3-E1000 is an easy way to gain wired gigabit network speeds for faster HD video streaming, gaming, web browsing, network storage and more.Common uses include adding wired gigabit network support to Macbooks, UltraBooks, or notebooks with no Ethernet connection, or replacing or upgrading network adapters in desktop PCs. USB network adapters can improve speeds vs. older 10/100 adapte…

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The next frontier for wireless LANs is 802.11ac, a standard that increases throughput beyond one gigabit per second. This concise guide provides in-depth information to help you plan for 802.11ac, with technical details on design, network operations, deployment, and monitoring.Author Matthew Gast—an industry expert who led the development of 802.11-2012 and security task groups at the Wi-Fi Alli…