diff --git a/include/net/tcp.h b/include/net/tcp.h
new file mode 100644
index 0000000..3225516
--- /dev/null
+++ b/include/net/tcp.h
@@ -0,0 +1,299 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * TCP Support with SACK for file transfer.
+ *
+ * Copyright 2017 Duncan Hare, All rights reserved.
+ */
+
+#define TCP_ACTIVITY 127		/* Number of packets received   */
+					/* before console progress mark */
+/**
+ * struct ip_tcp_hdr - IP and TCP header
+ * @ip_hl_v: header length and version
+ * @ip_tos: type of service
+ * @ip_len: total length
+ * @ip_id: identification
+ * @ip_off: fragment offset field
+ * @ip_ttl: time to live
+ * @ip_p: protocol
+ * @ip_sum: checksum
+ * @ip_src: Source IP address
+ * @ip_dst: Destination IP address
+ * @tcp_src: TCP source port
+ * @tcp_dst: TCP destination port
+ * @tcp_seq: TCP sequence number
+ * @tcp_ack: TCP Acknowledgment number
+ * @tcp_hlen: 4 bits TCP header Length/4, 4 bits reserved, 2 more bits reserved
+ * @tcp_flag: flags of TCP
+ * @tcp_win: TCP windows size
+ * @tcp_xsum: Checksum
+ * @tcp_ugr: Pointer to urgent data
+ */
+struct ip_tcp_hdr {
+	u8		ip_hl_v;
+	u8		ip_tos;
+	u16		ip_len;
+	u16		ip_id;
+	u16		ip_off;
+	u8		ip_ttl;
+	u8		ip_p;
+	u16		ip_sum;
+	struct in_addr	ip_src;
+	struct in_addr	ip_dst;
+	u16		tcp_src;
+	u16		tcp_dst;
+	u32		tcp_seq;
+	u32		tcp_ack;
+	u8		tcp_hlen;
+	u8		tcp_flags;
+	u16		tcp_win;
+	u16		tcp_xsum;
+	u16		tcp_ugr;
+} __packed;
+
+#define IP_TCP_HDR_SIZE		(sizeof(struct ip_tcp_hdr))
+#define TCP_HDR_SIZE		(IP_TCP_HDR_SIZE  - IP_HDR_SIZE)
+
+#define TCP_DATA	0x00	/* Data Packet - internal use only	*/
+#define TCP_FIN		0x01	/* Finish flag				*/
+#define TCP_SYN		0x02	/* Synch (start) flag			*/
+#define TCP_RST		0x04	/* reset flag				*/
+#define TCP_PUSH	0x08	/* Push - Notify app			*/
+#define TCP_ACK		0x10	/* Acknowledgment of data received	*/
+#define TCP_URG		0x20	/* Urgent				*/
+#define TCP_ECE		0x40	/* Congestion control			*/
+#define TCP_CWR		0x80	/* Congestion Control			*/
+
+/*
+ * TCP header options, Seq, MSS, and SACK
+ */
+
+#define TCP_SACK 32			/* Number of packets analyzed   */
+					/* on leading edge of stream    */
+
+#define TCP_O_END	0x00		/* End of option list		*/
+#define TCP_1_NOP	0x01		/* Single padding NOP		*/
+#define TCP_O_NOP	0x01010101	/* NOPs pad to 32 bit boundary	*/
+#define TCP_O_MSS	0x02		/* MSS Size option		*/
+#define TCP_O_SCL	0x03		/* Window Scale option		*/
+#define TCP_P_SACK	0x04		/* SACK permitted		*/
+#define TCP_V_SACK	0x05		/* SACK values			*/
+#define TCP_O_TS	0x08		/* Timestamp option		*/
+#define TCP_OPT_LEN_2	0x02
+#define TCP_OPT_LEN_3	0x03
+#define TCP_OPT_LEN_4	0x04
+#define TCP_OPT_LEN_6	0x06
+#define TCP_OPT_LEN_8	0x08
+#define TCP_OPT_LEN_A	0x0a		/* Timestamp Length		*/
+#define TCP_MSS		1460		/* Max segment size		*/
+#define TCP_SCALE	0x01		/* Scale			*/
+
+/**
+ * struct tcp_mss - TCP option structure for MSS (Max segment size)
+ * @kind: Field ID
+ * @len: Field length
+ * @mss: Segment size value
+ */
+struct tcp_mss {
+	u8	kind;
+	u8	len;
+	u16	mss;
+} __packed;
+
+/**
+ * struct tcp_scale - TCP option structure for Windows scale
+ * @kind: Field ID
+ * @len: Field length
+ * @scale: windows shift value used for networks with many hops.
+ *         Typically 4 or more hops
+ */
+struct tcp_scale {
+	u8	kind;
+	u8	len;
+	u8	scale;
+} __packed;
+
+/**
+ * struct tcp_sack_p - TCP option structure for SACK permitted
+ * @kind: Field ID
+ * @len: Field length
+ */
+struct tcp_sack_p {
+	u8	kind;
+	u8	len;
+} __packed;
+
+/**
+ * struct sack_edges - structure for SACK edges
+ * @l: Left edge of stream
+ * @r: right edge of stream
+ */
+struct sack_edges {
+	u32	l;
+	u32	r;
+} __packed;
+
+#define TCP_SACK_SIZE (sizeof(struct sack_edges))
+
+/*
+ * A TCP stream has holes when packets are missing or disordered.
+ * A hill is the inverse of a hole, and is data received.
+ * TCP received hills (a sequence of data), and inferrs Holes
+ * from the "hills" or packets received.
+ */
+
+#define TCP_SACK_HILLS	4
+
+/**
+ * struct tcp_sack_v - TCP option structure for SACK
+ * @kind: Field ID
+ * @len: Field length
+ * @hill: L & R window edges
+ */
+struct tcp_sack_v {
+	u8	kind;
+	u8	len;
+	struct	sack_edges hill[TCP_SACK_HILLS];
+} __packed;
+
+/**
+ * struct tcp_t_opt - TCP option structure for time stamps
+ * @kind: Field ID
+ * @len: Field length
+ * @t_snd: Sender timestamp
+ * @t_rcv: Receiver timestamp
+ */
+struct tcp_t_opt {
+	u8	kind;
+	u8	len;
+	u32	t_snd;
+	u32	t_rcv;
+} __packed;
+
+#define TCP_TSOPT_SIZE (sizeof(struct tcp_t_opt))
+
+/*
+ * ip tcp  structure with options
+ */
+
+/**
+ * struct ip_tcp_hdr_o - IP + TCP header + TCP options
+ * @hdr: IP + TCP header
+ * @mss: TCP MSS Option
+ * @scale: TCP Windows Scale Option
+ * @sack_p: TCP Sack-Permitted Option
+ * @t_opt: TCP Timestamp Option
+ * @end: end of options
+ */
+struct ip_tcp_hdr_o {
+	struct	ip_tcp_hdr hdr;
+	struct	tcp_mss	   mss;
+	struct	tcp_scale  scale;
+	struct	tcp_sack_p sack_p;
+	struct	tcp_t_opt  t_opt;
+	u8	end;
+} __packed;
+
+#define IP_TCP_O_SIZE (sizeof(struct ip_tcp_hdr_o))
+
+/**
+ * struct ip_tcp_hdr_s - IP + TCP header + TCP options
+ * @hdr: IP + TCP header
+ * @t_opt: TCP Timestamp Option
+ * @sack_v: TCP SACK Option
+ * @end: end of options
+ */
+struct ip_tcp_hdr_s {
+	struct	ip_tcp_hdr	hdr;
+	struct	tcp_t_opt	t_opt;
+	struct	tcp_sack_v	sack_v;
+	u8	end;
+} __packed;
+
+#define IP_TCP_SACK_SIZE (sizeof(struct ip_tcp_hdr_s))
+
+/*
+ * TCP pseudo header definitions
+ */
+#define PSEUDO_PAD_SIZE	8
+
+/**
+ * struct pseudo_hdr - Pseudo Header
+ * @padding: pseudo hdr size = ip_tcp hdr size
+ * @p_src: Source IP address
+ * @p_dst: Destination IP address
+ * @rsvd: reserved
+ * @p: protocol
+ * @len: length of header
+ */
+struct pseudo_hdr {
+	u8 padding[PSEUDO_PAD_SIZE];
+	struct in_addr p_src;
+	struct in_addr p_dst;
+	u8      rsvd;
+	u8      p;
+	u16     len;
+} __packed;
+
+#define PSEUDO_HDR_SIZE	(sizeof(struct pseudo_hdr)) - PSEUDO_PAD_SIZE
+
+/**
+ * union tcp_build_pkt - union for building TCP/IP packet.
+ * @ph: pseudo header
+ * @ip: IP and TCP header plus TCP options
+ * @sack: IP and TCP header plus SACK options
+ * @raw: buffer
+ *
+ * Build Pseudo header in packed buffer
+ * first, calculate TCP checksum, then build IP header in packed buffer.
+ *
+ */
+union tcp_build_pkt {
+	struct pseudo_hdr ph;
+	struct ip_tcp_hdr_o ip;
+	struct ip_tcp_hdr_s sack;
+	uchar  raw[1600];
+} __packed;
+
+/**
+ * enum tcp_state - TCP State machine states for connection
+ * @TCP_CLOSED: Need to send SYN to connect
+ * @TCP_SYN_SENT: Trying to connect, waiting for SYN ACK
+ * @TCP_ESTABLISHED: both server & client have a connection
+ * @TCP_CLOSE_WAIT: Rec FIN, passed to app for FIN, ACK rsp
+ * @TCP_CLOSING: Rec FIN, sent FIN, ACK waiting for ACK
+ * @TCP_FIN_WAIT_1: Sent FIN waiting for response
+ * @TCP_FIN_WAIT_2: Rec ACK from FIN sent, waiting for FIN
+ */
+enum tcp_state {
+	TCP_CLOSED,
+	TCP_SYN_SENT,
+	TCP_ESTABLISHED,
+	TCP_CLOSE_WAIT,
+	TCP_CLOSING,
+	TCP_FIN_WAIT_1,
+	TCP_FIN_WAIT_2
+};
+
+enum tcp_state tcp_get_tcp_state(void);
+void tcp_set_tcp_state(enum tcp_state new_state);
+int tcp_set_tcp_header(uchar *pkt, int dport, int sport, int payload_len,
+		       u8 action, u32 tcp_seq_num, u32 tcp_ack_num);
+
+/**
+ * rxhand_tcp() - An incoming packet handler.
+ * @pkt: pointer to the application packet
+ * @dport: destination UDP port
+ * @sip: source IP address
+ * @sport: source UDP port
+ * @len: packet length
+ */
+typedef void rxhand_tcp(uchar *pkt, unsigned int dport,
+			struct in_addr sip, unsigned int sport,
+			unsigned int len);
+void tcp_set_tcp_handler(rxhand_tcp *f);
+
+void rxhand_tcp_f(union tcp_build_pkt *b, unsigned int len);
+
+u16 tcp_set_pseudo_header(uchar *pkt, struct in_addr src, struct in_addr dest,
+			  int tcp_len, int pkt_len);