Wireshark-users: [Wireshark-users] identifying .dwg and .one files in gmail attachments

From: Support SwarajComm <support@xxxxxxxxxx>
Date: Mon, 29 Mar 2010 21:14:33 +0530

I have requirement like this. Need to block .dwg and .one files in mail attachment. I can implement firewall policy to block mail attachment with file signatures 41433130 (for .dwg files) and E4525C7B8CD8A74DAEB15378D02996D3 (for .one files). I am able to see these file signatures in all mails sniffer except gmail. Gmail is doing some encryption. What is the way to identify these files when using gmail. If I know some keyword related to these file types in gmail I can implement firewall policy to block that pattern. Any ideas?

Siva K