Monthly Archives: November 2009

How to control internet bandwidth usage on network?

Traffic Shaping and Prioritization is becoming more and more common in the corporate market. Most companies with remote offices are now connected via a WAN (Wide Area Network). Applications tend to become centrally hosted at the head office and remote offices are expected to pull data from central databases and server farms. As applications become more hungry in terms of bandwidth and prices of dedicated circuits being relatively high in most areas of the world, instead of increasing the size of their WAN circuits, companies feel the need to properly manage their circuits to make sure business-oriented traffic gets priority over best-effort traffic. Traffic shaping is thus a good means for companies to avoid purchasing additional bandwidth while properly managing these resources.

With a linux gateway, you have a very rich set of tools for managing and manipulating the transmission of packets. More details can be found at:, However, sometimes it might be difficult for you to deploy a linux gateway server.

This tutorial will guide to implement a passby bandwidth management solution, which enables you to manage internet bandwidth through a mirroring port on your switch. Port mirroring allows you to setup a port in the switch to receive packets of other ports. Setting up a mirror port does no change to your network topology, and it will not affect your network speed.

Let’s take WFilter as an example:

First, setup a mirroring port.

When the port mirroring is properly setup, WFilter will be able to monitor all computers internet activities.

Bandwidth Management Settings

Using WFilter’s bandwidth management feature, you can set a maximum accumulating bandwidth of each computer for a period time. In this example, each user can have 200M internet bandwidth every day. Only messengers and emails are allowed when the bandwidth limit is reached.

You also can setup a policy to block certain users when available
internet bandwidth of the entire network is not enough. For example,
When entire network traffic exceeds 80% of available internet
bandwidth, p2p traffic will be blocked.

Bandwidth Alert Settings

And the bandwidth alert feature will send you an alert email when the accumulating bandwidth of a computer is too large.

More information, please check “WFilter Enterprise”.
Other related links:
How to block websites at work during working hours?
How to block video streaming on company network?
How to block internet downloading?
How to monitor internet bandwidth?
How to monitor internet usage on company network?
How to block instant messaging on company network?
How to filter websites and restrict website access?

How to setup ip-mac binding in WFilter?

You may assign static ip addresses to computers manually or in your DHCP server. However, it is difficult to prevent users from changing their ip addresses or mac addresses. Though it is more reasonable to setup ip-mac binding in routers or switches, software solution is also a good option, as it is easier to setup and manage.

This tutorial will guide you to bind ip addresses to mac addresses in WFilter, an internet filtering and monitoring software product.

First, you need to setup a mirror port in your switch to do monitoring.
For how to deploy internet monitoring and filtering, check this guide: How to monitor internet usage?

Second, in “Control Settings”->”IP Management” of WFilter, you can setup ip-mac binding just by a few clicks.

When ip-mac binding is setup, internet access will be blocked when the user tries to change ip address or mac address.

Please notice: “ip-mac binding” feature of WFilter only works for single segment networks. It is because the real MAC addresses of computers can not be retrieved  in a multiple-segments network.


How to activate WFilter?

WFilter supports online activation and Email activation.

you choose to activate your product over the Internet, upon your
submisson the activation wizard will detect your Internet connection
and connect to a secure server to transfer your register key to us. The
registration is passed back to you, automatically activating WFilter,
if the register key is valid.

If you choose to activate your
product by email activation, you should input the register key in text
box and click the “confirm”. You will get an activation code. Please
send them to the support email box. The validation code will be sent
back to you within 24 hours. Please copy them in the valiation code
textbox to activate your product.

1. Steps of Online Activation

Online activation requires an available internet connection to connect to WFilter activation server.
1). In “Help”->”About” of WFilter, click “Product Activation”.

2). Input your key number and use “online activation” to do online activation.

3). Successful activation.

2. Steps of Email Activation

Online activation requires an available internet connection. If you can not connect to WFilter activation server, you also can use “Email Activation”.
1). Input your key number and use “email activation” to do online activation.

2). In “Email Activation”, copy the activation code and send to support email address.

3) It might take several hours to receive the reply email since the response email is sent manually.

4). In “Help”->”About” of WFilter, you need to enter the received validation code into WFilter.

3. De-activation

Sometimes, you might want to move the key to another computer. You need to de-activate this key first.
Click “deactivate” in “Help”->”About” to de-activate the key.

How to filter websites and restrict website access?

Unmanaged websites surfing is killing your productivity. And your computer and network is open to attack when visiting harmful sites.
So it is important to block unwanted websites in your network. Blocking of websites can be done in many ways. These include using free software and windows settings. There are even many add-ons for browsers like Firefox which let you check and restrict websites.

This tutorial will guide you to filter and block websites access in 4 ways.

1. manually editing the “host” file.

In “Local Disk (C:) > WINDOWS > system32> drivers > etc”, you will find a file named “host”. The Hosts file contains the mappings of IP addresses to host names. This file is loaded into memory (cache) at startup, then Windows checks the Hosts file before it queries any DNS servers, which enables it to override addresses in the DNS. This prevents access to the listed sites by redirecting any connection attempts back to the local (your) machine.
You may use “notepad.exe” to edit this Hosts file.
Example – the following entry blocks all files supplied by that DoubleClick Server to the web page you are viewing.

2. Opendns

OpenDNS offers DNS resolution for consumers and businesses as an alternative to using their Internet service provider’s DNS servers. By collecting a list of malicious sites, OpenDNS blocks access to these sites when a user tries to access them through their service.
OpenDNS enables you to block websites by 50+ categories. OpenDNS also provides whitelist and blacklist features to enable you to create exception cases (“always allow” and “always block”) to complement category-based filtering.

To use OpenDNS service, you need to change your DNS server settings manually.

More information, please visit

3. Router, Firewall or UTM

If you have a powerful router or UTM device, you also can setup web filtering on it.
For more information about UTM solution, please visit

4. Internet filtering products

You also can use internet filtering products to do web filtering. An internet filtering product can be deployed in your network, and it enables you to monitor, filter and block internet activities of all computers from a mirroring port.
More than web filtering, internet filtering product can also block file downloading, block p2p traffic and block messenger.

For internet filtering software, you can try “WFilter Enterprise”,

How to block instant messaging on company network?

Instant Messaging can be a benefit to business when used properly,
but IM is often abused by employees and poses significant liability and
security risks.

The free consumer IM client
programs in widest use, such as AIM, ICQ, Yahoo and MSN Messenger, pose many
security concerns. More than text-based chat, IM programs also include peer to peer file
transfer capabilities, which can pose security risks in two ways.
Internal users can send documents that may be confidential out of your
network, circumventing your network’s perimeter defenses against file
sharing programs or e-mail attachments. On the other hand, external
users can send files that might contain viruses or malicious code to
users on the internal network. In addition, a liability risk arises if
employees use the file transfer feature to share copyrighted music,
movie or software files in violation of the law.

To make your business efficient, it is necessary for you to monitor, filter and block instant messaging in your network.

You may want to apply an internet messenger usage policy like this:

1. Only authrozied users can use certain IM tools.

2. File transfer via messengers shall be blocked.

3. Only work-related IM accounts can be used.

As most firewall programs do not support that kind of feature, you need an internet monitoring and filtering program like “WFilter Enterprise”. “WFilter Enteprise” enables you to monitor, manage and block internet access of all computers on a mirroring port. For internet messaging blocking, WFilter supports:

1. Blocking certain messenger protocols.

2. Blocking file transfer via messengers.

3. Blocking certain messenger account using black/white list.


Block file transfer in messengers:

MSN black/white list:

More information, please check “WFilter Enterprise”.
Other related links:
How to block websites at work during working hours?
How to block video streaming on company network?
How to block internet downloading?
How to monitor internet bandwidth?
How to monitor internet usage on company network?
Internet monitoring software for business
How to filter web surfing?