SMTPFLTR

The SMTPFLTR sample filter captures and analyzes data sent by external clients using the SMTP protocol. The Firewall service attaches a new instance of the data filter to every inbound port 25 TCP session. The filter can be configured to look for a particular string in the SMTP message.

SMTPFLTR extends the firewall so that it secures SecureNAT clients, which do not have the Firewall client installed.

Note  In a SecureNAT scenario, IFWXFilter::AttachToSession and IFWXSessionFilter::FirewallEventHandler are not called, due to this filter's use of a class factory to create data filters.

SMTPFLTR is the example used in How to Create an Application Filter.

SMTPFLTR also creates a property sheet for the application filter, to extend the Microsoft Management Console (MMC). This procedure is described in How to Create a Microsoft Management Console Snap-in.

Methods Used in SMTPFLTR Sample

The SMTPFLTR sample uses the following methods:

IFWXConnection::SetProtocol

IFWXIOBuffer::GetBufferAndSize

IFWXIOCompletion::CompleteAsyncIO

IFWXSession::BindForClient

IFWXSessionFilter::Detach

IFWXSessionFilter::FirewallEventHandler

IFWXSocket::Close

IFWXSocket::Recv

IFWXSocket::Send

IFWXDataFilter::Detach

IFWXDataFilter::SetSockets

IFWXFilter::AttachToSession

IFWXFilter::FilterInit

IFWXFilter::FilterShutdown

IFWXFilterAdmin::GetFilterParameterSet

IFWXFilterAdmin::GetProtocol

IFWXFilterAdmin::InstallFilter

IFWXFilterAdmin::RegisterProtocolForFilter

IFWXFilterAdmin::UninstallFilter

IFWXFilterAdmin::UnregisterProtocolForFilter

IFWXFirewall::DuplicateFilterHookEvents

IFWXFirewall::GetNATSession