Kernel module providing system-wide TCP socket statistics via /dev/tcpstats.

The tcpstats module creates a read-only character device that streams
fixed-size 320-byte records containing per-connection TCP metrics including
addresses, ports, TCP state, congestion control parameters (cwnd, ssthresh),
RTT measurements, retransmit counts, ECN statistics, and process attribution.

Features include in-kernel filtering by port, TCP state, IP version, and CIDR
address ranges, with DoS protection via tunable concurrent reader and file
descriptor limits.