Though official Google Talk protocol is XMPP, it is more complicated and flexible than XMPP. Google Talk (GTalk) provides several ways for you to access your gtalk account, including:

• 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:

3. Blocked gadget

4. Blocked gmail chat

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.

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?

  Unmanaged internet access is harmful to your business.
  Without proper internet monitoring and filtering, you may suffer from:
  1. Lower productivity. Your employees might take hours for web surfing, chatting and watching videos.
  2. Slow internet speed. P2P programs or IPTV programs can easily consume most of your bandwidth. So normal business will not have enough available bandwidth.
  3. Unmanaged downloading will bring virus, worms and spyware, which is harmful to your network.
  4. Leaking of business documents and materials.

  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 Monitoring Performance

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:

#	Computers	Bandwidth	Total HTTP Requests	Recorded Percent	CPU	Memory
1	50	37.2M	16000	100%	35%	260,298K
2	100	35M	20000	100%	38%	280,576K
3	200	31M	40000	100%	58%	294,561K
4	400	33M	80000	100%	68%	372,786K
5	600	32.3M	120000	100%	80%	540,151K
6	1000	32.6M	200000	60%	99%	540,664K

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:

#	Computers	Bandwidth	Total HTTP Requests	Recorded Percent	CPU	Memory
7	1000	32.7M	200000	100%	90%	820,640K

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

#	Computers	Bandwidth	Total HTTP Requests	Recorded Percent	CPU	Memory
1	50	34.9M	10000	100%	45%	197,392K
2	100	34.9M	20000	100%	45%	210,196K
3	200	31M	40000	100%	45%	270,960K
4	400	32.9M	80000	100%	45%	364,234K
5	1000	28.6M	200000	58.84%	100%	540,664K

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

Test Environment

1	Network	100M ethernet
2	Test Client	Intel(R) pentium(R) Dual 1.80+1.80GHz , 1G RAM
3	Test Monitoring Server	Intel(R) Celeron(R) 2.66GHz, 1G RAM
4	WFilter Version	WFilter 3.3
5	Switch	Tplink TL-SF1008

  WFilter 3.3 is under alpha testing now. The new version will add "Bandwidth limit", "Url keywords blocking", "Website visit quota" and other exciting features.
  1. "Bandwidth limit". You can set bandwidth limit for each computer, or blocking certain internet traffic when internet bandwidth is too high. This feature can help you to manage company bandwidth flexibly.
  2. "Url Keywords Blocking", blocking url/webpage by keywords category. You may use this feature to block certain keywords from being searched in search engines.
  3. "Website visit quota", by this feature, you are able to set visit time quota for each website category. For example, "news" websites can be limited to "1 hour" for each day.


 

     It is said that Google talk uses Jabber protocol to communicate.
     However, Google talk has more flexible ways to connect:
     1. Using Jabber standard tcp port 5222.
     2. Using TLS port 443.
     3. Using web chatting on port 80.

     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...

Silently monitoring using ARP Spoof

Most monitoring softwares require a broadcasted hub or a port mirror switch, or the monitoring program need to be installed at the proxy server.

If you don't want to buy additional device and change your network topology, IMMonitor provides an arp-spoof tool to help you. However, we recommend you use a port mirror switch for long term use because arp-spoof will has some shortcomings:

Always do not spoof more than 30 computers and keep your computer stable. If your computer hangs or power off when spoofing, the computers being spoofed will lose connections.

Run ARP Spoof from IMMonitor

 

You need to restart your computer for the first time running arp-spoof. After restart, run arp-spoof again, choose your adaptor and set the mode to "Full duplex", check the computers you want to spoof and click "Start ARP Spoof".

Open IMMonitor console with ARPSpoof running, set "Mode" to "By IP Address" in "Monitor settings". Then open "Online Computers" of IMMonitor, you will able to monitor other computers.

IMMonitor Features

Chat monitor: MSN chat monitor, AIM chat monitor, Yahoo chat monitor, ICQ chat monitor, QQ chat monitor, live messenger monitor.

Email Monitor: monitor emails, monitor email content, monitor company email, monitor pop3 email, monior smtp email, monitor incoming and outgoing emails.

Web surfing monitor.

 

 

Chat monitor using IMMonitor

It's really important for companies to monitor employees instant messaging to prevent leaking of corporations business secret, and increase working productivity.

It's also important for parents to monitor kids chat activities to protect them.

IMMonitor is designed to silently monitor chat content, monitor email transfer and web surfing activities in local network without installing any programs in client computers.

Here I give a short description of how to using IMMonitor to monitor chat in your network:

To install IMMonitor, please read How to install and deploy IMMonitor first.

Login into IMMonitor.

Login into IMMonitor using username admin, initial password 123456.

After login, you will be able to see all online computers detected. If you can not see other computers in your network. Your deployment of IMMonitor is possibly to be incorrect. Please check "How to deploy IMMonitor" chapter in "Getting started with IMMonitor".

Online computers list:

The figures under "Chat logs" will show monitored chat message number. Click the figure you will be able to see all messenger id which have been used in this computer.

 

Click a messenger id and choose a date, you may see all chat history logs and chat content in that day of this id.

  Notice:

      Incorrect deployment of IMMonitor will no be able to monitor others computers, it is important to read "Gettting started with IMMonitor" first.