This read-write value configures the minimum allowed TCP header size, in bytes, accepted by the switch, and only takes effect when First Fragment protection is enabled. Admins use it to reject malformed or deliberately undersized TCP headers commonly used in denial-of-service exploits, with a default minimum of 20 bytes matching the standard TCP header length. Leaving agentSwitchDenialOfServiceTCPHdrSize at its default of 20 causes the switch to drop any TCP packet whose header claims to be smaller than a standard 20-byte header.