International Business Machines Corporation

Steven Ashley Mazur

Paul Coccoli

Gregory Lyle Galloway

David Allen Dennerline

Matthew Joseph Kubilus

Ronald B Williams

John William Court

Joseph Karl Vossen

A network appliance is configured to provide inline traffic inspection for all flow through the device, to selectively intercept based on traffic content or policy, and to modify intercepted traffic content, all without connection termination and re-origination. Content modification may involve substitution of traffic content with smaller or larger content, in which case the device provides appropriate sequence number translations for acknowledgements to the endpoints. This streaming rewrite may occur on a byte-at-a-time basis, while keeping the session alive and without a need to proxy it. The appliance enables transmitted TCP data to be modified inline and then reliably delivered without the overhead of forwarding packets through a full-blown TCP stack. Rather, the approach relies upon an initiator entity's TCP stack for congestion control, as well as the receiving entity's re-transmission behavior to determine how the device manages packets internally.

Transparent inline content inspection and modification in a TCP session

A network-based appliance includes a mechanism to intercept, decrypt and inspect secure network traffic flowing over SSL/TLS between a client and a server. The mechanism responds to detection of a session initiation request message from the client, the message being received following establishment of a TCP connection between the client and server. The mechanism responds by holding the session initiation request message, preferably by creating a fake socket to a local process, and then diverting the request message over that socket. The TCP connection is then terminated, and the mechanism initiates a new session in initiation request message, all while the original session initiation request message continues to be held. The server responds with its server certificate, which is then used by the mechanism to generate a new server certificate. The new server certificate is then returned to the requesting client as the response to the session initiation request message.

Intercepting, decrypting and inspecting traffic over an encrypted channel

A network-based appliance includes a mechanism to enable the appliance to extract itself from man-in-the-middle (MITM) processing during a client-server handshake and without interrupting that connection. The mechanism enables the appliance to decide (e.g., based on a rule match against a received server certificate) to stop performing MITM during the handshake and thus to de-insert itself transparently, i.e., without interfering or signaling to either end of the session that this operation is occurring. Once the connection is abandoned in the manner, the appliance ignores additional traffic flow and thus can free up processing resources (CPU, memory, and the like) that would otherwise be required to decrypt the connection (even if no further inspection or rewrite processing would be expected to occur).

TLS connection abandoning

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Johns Creek, GA, United States of America

Steven Ashley Mazur