+
+#define TCPOPT_EOL 0
+#define TCPOPT_NOP 1
+#define TCPOPT_MAXSEG 2
+#define TCPOLEN_MAXSEG 4
+#define TCPOPT_WINDOW 3
+#define TCPOLEN_WINDOW 3
+#define TCPOPT_SACK_PERMITTED 4 /* Experimental */
+#define TCPOLEN_SACK_PERMITTED 2
+#define TCPOPT_SACK 5 /* Experimental */
+#define TCPOPT_TIMESTAMP 8
+#define TCPOLEN_TIMESTAMP 10
+#define TCPOLEN_TSTAMP_APPA (TCPOLEN_TIMESTAMP+2) /* appendix A */
+
+#define TCPOPT_TSTAMP_HDR \
+ (TCPOPT_NOP<<24|TCPOPT_NOP<<16|TCPOPT_TIMESTAMP<<8|TCPOLEN_TIMESTAMP)
+
+/*
+ * Default maximum segment size for TCP.
+ * With an IP MSS of 576, this is 536,
+ * but 512 is probably more convenient.
+ * This should be defined as MIN(512, IP_MSS - sizeof (struct tcpiphdr)).
+ */
+#define TCP_MSS 512
+
+#define TCP_MAXWIN 65535 /* largest value for (unscaled) window */
+
+#define TCP_MAX_WINSHIFT 14 /* maximum window shift */
+
+/*
+ * User-settable options (used with setsockopt).
+ */
+#define TCP_NODELAY 0x01 /* don't delay send to coalesce packets */
+#define TCP_MAXSEG 0x02 /* set maximum segment size */