Invalidity dossier
US 6202081
Method and protocol for synchronized transfer-window based firewall traversal
Current assignee: HP Inc
Added 9/21/2026, 10:34:04 AM
Active provider: DeepSeek · deepseek-flash
Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview — US6202081B1
Title: "Method and protocol for synchronized transfer-window based firewall traversal"
Patent number / application: US6202081B1; Application US09/119,987
Assignee / inventor: Original assignee 3Com Corp.; inventor Stanley T. Naudus. The source lists current assignees as HP Inc and Hewlett Packard Enterprise Development LP.
Key dates: Priority/filing date 1998-07-21; granted and published 2001-03-13; anticipated expiration 2018-07-21. Legal status: Expired – Lifetime (as listed; the source notes legal status is an assumption, not a legal conclusion).
Purpose: The invention relates to computer networks, specifically a method and protocol for synchronized transfer-window based firewall traversal. Firewalls protect a network (e.g., a LAN) from outside attacks (e.g., from the Internet) using packet mode, circuit mode, and application gateway filtering. The source notes firewalls provide little protection against packets lacking authentication, state, time, or pre-assigned sequence numbers (e.g., TCP SYN denial-of-service attacks).
Plain-language scope: Per the excerpt, the firewall traversal protocol and method let a first network device inside a firewall coordinate a connection with a second device outside the firewall, with secure firewall traversal information sent from inside to outside. A preferred embodiment coordinates the connection from inside the firewall. The protocol includes four messages: an open-transfer-window message, an open-transfer-window acknowledgment, a close-transfer-window message, and a close-transfer-window acknowledgment; the source states it is not limited to four messages. The open message opens a "virtual" data transfer-window in the firewall and carries information such as a network address, a starting firewall traversal sequence number, an SPI or other encryption indicator, and transfer rate information. The acknowledgment includes this information and synchronizes; the close messages close the window and authenticate using information from the open message.
What the excerpt does not establish: It does not provide the full specification, claims, drawings, or prosecution history; it does not establish exact claim scope, embodiments beyond those summarized, or completeness of prior-art discussion. No litigation, ownership-transfer, validity, or prior-art conclusions are drawn here.
Source: https://patents.google.com/patent/[US6202081](/patent/US6202081)/en
Generated 10/1/2026, 10:01:25 PM
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PTAB challenges
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Assignment history
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Prior art
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Obviousness
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Derivative works
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