In case you don’t have a mirroring device, you can use this deployment instead. It’s also powerful and reliable.

1. Network Topology

The virtual openwrt gateway is connected to original gateway by a cable. It serves a new subnet to client devices.

2. Steps to build the openwrt virtual gateway.

The host PC runs a windows system and shall be connected with a wired network card.

1). Download and install VirtualBox

Download URL: https://www.virtualbox.org/wiki/Downloads

2). Download the pre-built openwrt vm.

Download URL: openwrt for wfilter

Uncompress it to a local directory, double click file “openwrt_1.vbox”

You need to modify the “network settings” of this vm, change “Adapter 1″ and “Adapter 2″ to the network card which is connected to your current gateway.

Now you can start the openwrt vm.

3). Launch openwrt web UI

The vm is assigned with a default ip address “192.168.151.1″, to access its web UI, you need to add a 192.168.151.100 ip address to your current adapter.

Now you can access openwrt web UI in your browser, from url http://192.168.151.1

Username is root, default password is: im1234

4). Configure Wan Interface

You can configure wan interface in “Network”->”Interfaces”->”BR”.

The default Wan ip address is “1.1.1.1″, you need to modify it according to your network settings.

Assign a valid ip address and the gateway ip address to the wan interface.

4). Configure Lan Interface

You don’t have to modify the lan interface settings, unless you want to change the default subnet “192.168.151.0″.

3. Disable DHCP in current gateway

The existing dhcp server(usually the gateway) shall be disabled.

4. Setup WFilter.

Now the virtual gateway is acting as a gateway and dhcp server in your network. Devices obtain ip addresses from this virtual gateway can be monitored in WFilter.

In this example, we will demonstrate you to monitor and filter PPPOE clients with WFilter Free. Please notice that only non-encrypted and uncompressed PPPOE traffic can be supported. So the first step is to configure your PPPOE server for non-encryption and non-compression.

1. PPPOE server settings

Let’s take windows 2003 and RouteOS for examples.

1). 2003 Server Configuration

If you are using windows 2003 server as the PPPOE server, please follow below steps to configure:

In “Properties” of the “Routing and Remote Access”, disable “software compression” and “LCP” in the “PPP” tab.

Edit “remote access policy” for “no encryption” in “Edit Profile”. Notice: The default two policies shall all be modified.

2). ROS Configuration

If you are using routeOS as PPPOE server, please follow these steps to disable compression and encryption:

In “PPP” tab of “Profiles”, click “Protocols” and disable compression and encryption.

2. Monitor PPPOE clients in WFilter

2.1) Choose the internal adapter

Now WFilter is able to parse PPPOE traffic. In this example, we just install WFilter free in the windows 2003 PPPOE server.

You need to choose the internal adapter as the “monitoring adapter” in “System Settings”->”Monitoring Settings” of WFilter.

2.2). Setup client policy

Add a block policy to block web surfing.

Apply this policy to PPPOE clients’ ip ranges

2.3). Check Blocking

PPPOE clients get blocked.

Blocking events in WFilter.

OpenWrt is a highly extensible GNU/Linux distribution for embedded devices. As a third party firmware, openwrt can extend your wireless router into a powerful Linux system. With openwrt, even if your router hardware does not support “port mirroring” function, you can also enable traffic mirroring by software mirroring.

This blog will guide you to install “port-mirroring” program in your openwrt router and deploy WFilter for internet monitoring and filtering. We assume you already has an openwrt router, if not, please check openwrt homepage to get the latest firmware.

2. Port-mirroring program

Port-mirroring is an open source project sponsored by IMFirewall Software, it is designed to mirror network traffic on linux systems.

2.1. Installation

For detailed installation guide, please check Port-mirroring open source packet mirroring. In this guide, let’s take linksys wrt54g router as an example (with openwrt backfire firmware). Steps:

a). Update openwrt package list.

b). Install the port-mirroring program

opkg install http://port-mirroring.googlecode.com/files/port-mirroring_1.2-1_backfire_brcm47xx.ipk.

2.2. Configuration

You need to edit /etc/config/port-mirroring to set the mirroring target and mirrored source interfaces.

In this example, we choose “wlan0″ wireless adapter as the mirrored source interface.

2.3. Start Port-mirroring

/etc/init.d/port-mirroring start

3. Check monitoring in WFilter

Now WFilter shall be able to monitor client computers.

• 1). Official  “Google Talk” client.
• 2). Gmail chat in google mail account.
• 3). Google Talk Gadget — a web version of Gtalk.

This makes it complicated for you to block usage of google talk on company network. This tutorial will guide you to block google talk, gmail chat and google talk gadget using WFilter.

WFilter identifies Google talk connections by signature matching. Blocking google talk is simple in WFilter.

The below examples demonstrates blocking of google talk and gmail chat.

1. Blocking of jabber, gmail chat and gadget

Set a blocking policy in WFilter to block jabber and google talk:

2. Blocked Google talk:

4. Blocked gmail chat

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.

Figures:

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?

  Therefore, it is important for you to monitor and manage employees internet activity. This guide will introduce you several aspects of deployment and usage of internet monitoring and filtering software. Please be aware that I am only going to talk about internet access monitoring, which does not include screen monitoring, USB forbiding and keystroke recording. The latter requires you to install a client agent in every computer. And internet monitoring only needs to be installed near the internet entrance.

How to deploy internet monitoring software?

  Though internet monitoring only needs to be installed near internet entrance, it is quite different for different network topologies.
  For “Router<->Switch<->Computers” networks, you need to setup a mirroring port in the switch to enable monitoring. If you are using ISA or wingate proxy server, you can do monitoring right in the proxy server.

How to monitor internet bandwidth?

  Upon properly deployed, you can easily monitor internet bandwidth and activities using internet monitoring software.
  Below let me take “WFilter Enterprise” as an example:
 
  Use WFilter’s “Active Connections” feature, you can have a clear view of all connections in your network.

Connections of a particular computer, you can kill established connections if you want.

For more details about “monitor internet bandwidth”, please refer to: How to monitor internet bandwidth?

How to monitor internet usage?

In “Online computers” of WFilter, click the numbers under each title to view detailed records.

How to block downloading?

To save bandwidth, inproper downloading shall be blocked. The below figure shows blocking of large size files and blocking by video files.

Blocking of video files.

For more details, please refer to “How to block downloading?”.

WFilter is designed to monitor a network with no more than 1000 computers, and the available internet bandwidth of the entire network shall be no more than 100Mbit/s.

Since WFilter is software, the performance depends a lot on the hardware performance. Higher bandwidth requires faster CPU, and more monitored computers require more RAM. Therefore, we recommend you to provide 1M available RAM for each monitored computer.

Below is a performance test result for HTTP request of WFilter 3.3 file-based version:

As we can see from the above table, when monitored computers number reachs 1000, the “recorded percent” decreased to 60% suddenly. And we noticed the memory only slightly increased, so it shall because lack of memory. Therefore we added the monitoring computer RAM to 2G, and do the test again:

And the test of WFilter 3.3 database version(SQL Server) performance has the similar result:

The performance of 1000-user can also be improved by adding RAM of the monitoring computer.

Test Environment

     So you will not able to block Google talk by simply blocking Jabber standard port. And 443, 80 ports are essential internet ports which shall not be blocked.

     WFilter makes it simple to block google talk. Google talk connections can be identified and blocked by signature matching. And all these can be done just by one click as below:

     More information, please refer to: http://www.imfirewall.com/en/protocols/Jabber.htm.

AOL Instant Messenger (often referred to as “AIM”) is an instant messaging application that allows registered users to communicate in real time via text, voice, and video transmission over the Internet. It is maintained by AOL LLC. The official website is www.aim.com.

AIM is widely used all over the world. However, employees are using AIM to chat privacy topics, send and receive files, which will decrease working productivity, waste time and raise security risk.

So it is important to block AIM in enterprise network.

How to block AIM in your network?

AIM messenger can connect in several ways. Default is TCP port 5190. However, if you block AIM port 5190 in your firewall. It will turn to use port 80, 443 instead. And also, AIM messenger can use a HTTP/SOCK4/SOCK5 proxy server to reach the server. Even the worth, AIM traffics through port 80 using HTTP protocol, if you allow your employees to browser website, the 80 port must be available. And AIM has official clients, and many unofficial clients like gaim, trillian are also popular.
So, is blocking AIM mission impossible?

Of course not, but professional internet filter tools are needed. To block aim traffic, it needs the blocking aim tool has the ability to pick up aim traffic from large amount of connections.

I recommend you use WFilter to block aim, block msn and block messenger.

WFilter related features:

• Monitor AIM and ICQ messenger usage.
  
• Record chat contents of AIM and ICQ.
  
• Record files transfered by AIM/ICQ.
  
• Implement a policy to block AIM/ICQ or certain AIM/ICQ accounts.
  
• Block AIM file transfers, block icq file transfers.
  
• Support offical messenger client and other third party clients like gaim, trillian.

WFilter other monitor features:

Chat Monitor, MSN Messenger Chat Monitor, Yahoo Chat Monitor and other instant messenger monitor, block MSN, block Yahoo, block AIM, and other instant messenger block, block p2p, block p2p traffic, filter internet, block internet, internet monitor, monitor employee internet activity…