Filtering data transmitted over the Internet into a company's network for viruses, Trojans, worms and spam is an important part of a security concept to protect the local network from being taken over by attackers. Those filters are either implemented on the client, on a local network server or on a proxy system, depending on how the respective data is transmitted over the network. Where mail and file server are often locally installed, web servers are usually remote and require a proxy for filtering. A proxy however takes over communication for the client and thus might change important communication parameters such as the remote machine's identification when using SSL. We have developed several application level content filters running on bridges, i.e. ISO/OSI level 2 devices filtering ISO/OSI level 7 content. This papers gives an overview of our research and discusses advantages of application level filtering on bridges.