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TCP Sweep – What is causing it?

Filed under :Knowledgebase

Running a company as a reseller web host, you’ll often receive an email from your upstream provider reporting security violations. If you do not correct the problem in a timely manner, your upstream provider may block inbound and outbound traffic from the affected server.

Today, we received a security report from Savvis indicating that one of our Windows 2003 server is sweeping TCP port 445. This obviously violates their “Acceptance Use Policy”. Here is the snippet of their log entry.

22:11:55 [IP ADDRESS HIDDEN] 0.0.0.0 [TCP-SWEEP]
(total=24,dp=445,min=32.42.39.128,max=32.42.39.174,Jun01-03:20:30,Jun01-03:20:30) (MOW-Ams01)

TCP sweeping is a scanning of TCP port, in this case port 445. Since our client has no idea about TCP sweep, chances are the server is running a malicious code. The machine is either compromised, or someone unknowingly installed a malicious 3rd-party software. Regardless, the server is running a unwanted software which attacks other servers.

The best way to resolve this issue is to rebuild the OS, and restore the system back to a healthy state. It is a good idea to look at the software that are installed on the system, and determine the root cause of the compromise and prevent it from happening again.

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Cloud hosting Overview

Filed under :Knowledgebase

What is cloud hosting?

Cloud hosting is a web hosting service evolved from the cloud computing, which is offered from a network of “clustered” servers that are working together to offer a reliable service. Depending on the size of the cloud, the network may consist of tens or hundreds of servers that are located in the data centers that are scattered in all over the states. The companies like Amazon, Google and Yahoo offer their services over a cloud network, which delivers fault-tolerant availability.

Web hosting service offered on a traditional dedicated server encounters multiple points of hardware failure. Even with redundant hardware setup such as dual power, RAID disks, and dual LAN of a dedicated server, a dedicated server do fail time-to-time and the service outage occurs either planned or unplanned. Hardware expansions, software upgrades, and other planned maintenance all lead to bring the server down for minutes to several hours. When a dedicated server experiences an outage, your business is at risk and the reputation will be severely tarnished as visitors are unable to reach your website or experience interrupted service. Search engines also penalize your website on search rankings if outage occurs multiple times.

On the other hand, cloud hosting service is offered by a network of server resources scattered over multiple data centers and single failure will not affect your hosting service. Users can easily expand their server resources without an outage, and enjoy enhanced security, performance and high availability. Unlike traditional dedicated hosting, the cloud hosting enable you to add additional hardware resources to your server with no interruption to your business.

A video from GoGrid on cloud hosting

The following video released on YouTube helps you understand “Cloud Computing” in plain English.

Cloud Hosting Scalability

One of the biggest advantage of using cloud hosting is the scalability. As your server requirements grow, you can easily expand your server resources without worrying about physically moving your server from one machine to another. With cloud hosting, you’ll only pay for the quantity of computing resource consumed. If you don’t need your server to stay up 24×7, you can turn it off and save money. It’s like a flipping a switch to turn on or off your server; and only pay while the server is servicing the requests.

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Bandwidth and Data Transfer, and how much do I need?

Filed under :Knowledgebase

It is very common to use bandwidth and data transfer synonymously, but the two words have distinctive meanings. The bandwidth refers to data tranfer rate, while the data transfer denotes amount of data transferred. Although they are different, the two words are interchangeably used in the web hosting industry.

What is bandwidth?

Bandwidth is defined as amount of data transmitted over unit time. In other words, bandwidth is how fast data flows on a given transmission path or medium. The bandwidth of T1 transmission media is 1.54 Mbps (Mega bits per second), and OC-3 is approximately 155 Mbps. If a given facility has higher bandwidth, the website will load faster because it can transfer more data per second.

What is data transfer?

Data transfer refers to amount of traffic generated and transported from one location to another. From web hosting perspective, the data transfer refers to amount of data that is transferred to and from your website either by you uploading files, your visitors viewing and downloading files, and emails transported from the server to your computer. Data transfer is measured in bytes (B), kilo bytes (1 thousand bytes or KB), mega bytes (1 million bytes or MB) giga bytes (1 billion bytes or GB) or tera bytes (1 trillion bytes or TB). If you upload 1MB file, and your visitors download the file 999 times, you’ve just transferred 1,000 MB or 1GB of data.

How much data transfer do you need?

Depending on what type and size of information you provide to your visitors and how many visitors you expect your website, your data transfer requirement will greatly change. If you provide mostly static text, your data transfer requirement will be relatively small. On the other hand, if you offer multimedia files such as MP3, WAV, AVI and MPG files, your data transfer requirement will be a lot higher. Multiply the data you’ll be providing to your yours by number of visitors you expect on a given month, and you’ll have a rough idea of required data transfer amount.

To give you numeric examples, think of a site offering static text. If a website delivers 10,000 pages per day with average page size of 20 KB, the data transfer per month will be 6GB (30 days x 10K pages x 20 KBytes). Average website receives about 50 visitors per day, and uses less than 300 MB of data tranfer.

Truth about unlimited data transfer (or bandwidth)?

Even though the cost of bandwidth has been reduced significantly over the last several years, providing higher bandwidth will cost more money to web hosts. To provide more bandwidth to the users, it will generally require more server resources to provide such services. Any host offering unlimited data transfer at any price will not likely be in business if their users do use them. The limiting factor is the server resources which prevents a user from using unlimited bandwidth. The bottomline is there is no such thing as unlimited data transfer.

This article is written by Scott Seong, President and CEO of Edula, Inc. If you have questions or comments about this article, please forward them to feedback@edula.com.

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WEB HOSTING RESOURCES