IMFirewall P2P Classify Engine Introduction

1    Introduction

IMFirewall Software is a professional Internet filtering software provider. We focus on Internet information security and providing customers with a comprehensive approach to manage the Internet usage of enterprise network since founded in 2004. By 2007-10, protocols number supported in our pattern database has reached over 90. And our pattern analysis team is monitoring and analyzing protocols everyday.

2       Supported Pattern Type

Three pattern types are supported:

1.      Signature Pattern

You may call it digit signature. As most p2p programs do not has a fix port range nor central servers. The only way to match them is by signature match. IMFirewall pattern matching engine scans every connection for signature of existing protocols..

2.      Port Pattern

IMFirewall pattern matching engine can also recognize protocols by port or port range.

3.      HTTP Pattern

Because more and more protocols are using HTTP protocol or HTTP tunnel to communicate, our pattern-matching engine also checks http mime-header for signatures. HTTP pattern is powerful to recognize http-based protocols.

3       Pattern Matching Speed

We test the speed of each pattern when new pattern found, the standard speed is 20,000 matches in 1 second.

4       Quick Response for New (Updated) Protocols

As protocols may vary from time to time, it is necessary to keep the pattern database up to date in time.

We have a protocol/programs monitoring system, which will monitor the website and files on official websites of each protocol. Once there is a change, the system will notify our protocol analysis team to test it.

This makes us a quick response for new (updated) protocols. Usually, a updated protocol can be added to our pattern database in 2-3 business days.

Links: Supported protocols list of WFilter

Someone told me WFilter can not block bittorrent downloading. So I did some research yesterday.

I downloaded both bittorrent and bitcomet from their official website. I also downloaded an availble torrent file from bittorrent.com.

Turning "Block P2P" on in WFilter console, then use bitcomet to download, the download never begined. However, when I use bittorrent to download, it will start downloading after trying for a few seconds.

This is really interesting. Since WFilter can detect and block bittorrent traffic using pattern match, this should not happen. So what's the reason? After detailed analysis of the network traffic, I found bittorrent also download data directly from bittorrent.com using http protocol. That means bittorrent not only use p2p downloading, but also can download files directly from the website.

Knowing that, I added "bittorrent.com" in the black list of wfilter's website black&white list, then did the download again. Aha, bittorrent never be able to download any files.

Here we've added some configuration examples of wfilter:

We've added some wfilter deployment examples in pratice.

MSN, also called as live messenger is widely used. Windows Live Messenger gives you brilliant ways to connect and share your photos (and other stuff). Contact lists, emoticons, instant access to your friends.

However, sending and receiving files using MSN will face some security risk. 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.

How to block msn file transfer?

MSN transfers files using dynamic ports which are negotiated. So it is impossilbe to block msn file transfer ports.

WFilter provides a efficient way to block msn file transfer. By using WFilter, It is very easy for you to detect and block MSN file transfers.

A more detailed example can be found here:

Example of blocking msn

A pure peer-to-peer network does not have the notion of clients or servers, but only equal peer nodes that simultaneously function as both "clients" and "servers" to the other nodes on the network. This model of network arrangement differs from the client-server model where communication is usually to and from a central server.

Some networks and channels such as Napster, OpenNAP and IRC server channels use a client-server structure for some tasks (e.g. searching) and a peer-to-peer structure for others. Networks such as Gnutella use a peer-to-peer structure for all purposes, and are sometimes referred to as true peer-to-peer networks, although Gnutella is greatly facilitated by directory servers that inform peers of the network addresses of other peers.

As you can see from above, a peer-to-peer network is complex and it is almost impossible for you to block p2p in the router or the gateway.

WFilter provides a efficient way to block p2p traffic by signature match. By using WFilter, It is very easy for you to detect and block p2p traffic and file downloading.

WFilter related features:

• Detect p2p traffic in your network.
• Implement a policy to block certain p2p traffic.
• Support over 30 p2p protocols, cover most common p2p softwares.
• Define a file extension list forbidden from being download.