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User Manual
Page 44 of 66
opening the firewall to address the needs of specific types of applications.
Firewall Settings
Enable SPI
SPI ("stateful packet inspection" also known as "dynamic packet filtering") helps to prevent cyberattacks by tracking more state per session.
It validates that the traffic passing through that session conforms to the protocol. When the protocol is TCP, SPI checks that packet sequence numbers are
within the valid range for the session, discarding those packets that do not have valid sequence numbers.
Whether SPI is enabled or not, the router always tracks TCP connection states and ensures that each TCP packet's flags are valid for the current state.