InfraGuard

Detection rule: SYN Resend Anomaly

Repeated SYNs with differing seq during connection setup.

WarningTCP Stream IntegritySuricata

What it detects

Repeated SYNs with differing seq during connection setup.

Why it fires

Often retries, but can indicate SYN scanning or session manipulation.

Worst case

Port scanning

Matching signatures

syn resend

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