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Window Scaling (RFC 1323), 1/3
Previously in Windows, but off by default
We ran into a number of problems testing it for Vista:
IGD problems: multiple popular vendors, popular models
Popular vendor #1, several models having SPI block TCP handshake with WS: automatic detection and recovery at end system
Popular vendor #2, models with SPI drop packets on connections after a large scaling factor (>2) successfully negotiated during initial handshake: no way to recover at TCP layer
Firewall problems: multiple vendors have almost identical bug in old versions
Multiple popular vendors, multiple old models (one only if a non-default feature enabled) drop packets if scaling factor > 2 has been negotiated
Core Issue: Broken firewall logic that does not scale window in TCP headers correctly while determining how much data to let through
PPT Version