Invalidity dossier
US 8219675
System and method for correlating IP flows across network address translation firewalls
Current assignee: NetScout Systems Texas LLC
Added 9/21/2026, 12:39:23 PM
Active provider: DeepSeek · deepseek-flash
Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview — US8219675B2
Title: "System and method for correlating IP flows across network address translation firewalls."
Patent number / application: US8219675B2 (application US12/636,144; publication US20110145391A1).
Inventor / assignee: Inventor Aleksey G. Ivershen; original assignee Tektronix Inc. The source lists a current assignee of NetScout Systems Texas LLC and later reassignments, but per the instructions those ownership details are excluded from this overview.
Key dates (as listed): priority/filing date 2009-12-11; publication 2011-06-16; granted 2012-07-10; legal status "Active"; adjusted expiration 2030-05-10. Google notes legal status and priority date are assumptions, not legal conclusions.
Purpose: To correlate data packets for multi-hop calls across networks when a Network Address Translation (NAT) firewall has modified packet addressing. NAT firewalls replace source IP address/port numbers with the NAT's IP/new port, storing pairs in a translation table, which hides the private address space. The disclosed approach correlates pre-NAT and post-NAT flows without requiring access to NAT translation tables, and is largely independent of application protocols.
Plain-language scope: The method exploits invariant parts of packets passing through the NAT. OSI Layer 5/Layer 7 data is shipped as-is after address translation, so a checksum key (e.g., CRC-32 or MD5) computed from that L7 data should be identical on both sides of the firewall. Matching checksum keys identify related packets; keys within a specified time window on the second side are analyzed to account for transit time, firewall delay, and clock errors. On each side, related packets can also be correlated via a 5-tuple association (server IP, client IP, source port, destination port, and a further part, cut off in the excerpt). Passive L5/L7 collection supports correlation without NAT table data.
What the excerpt does not establish: The full text of the claims, the complete 5-tuple definition, the full description and any figures, the specific prior-art references cited during prosecution, and the scope of claim coverage are not established here. No determination of validity, infringement, or ownership is made.
Source: https://patents.google.com/patent/[US8219675](/patent/US8219675)/en
Generated 10/1/2026, 10:01:04 PM
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Litigation summary
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Proceedings on file (0)
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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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Extensions
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Derivative works
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