Index: head/usr.bin/netstat/inet.c
===================================================================
--- head/usr.bin/netstat/inet.c
+++ head/usr.bin/netstat/inet.c
@@ -85,6 +85,8 @@
 #include "netstat.h"
 #include "nl_defs.h"
 
+#define max(a, b) (((a) > (b)) ? (a) : (b))
+
 #ifdef INET
 static void inetprint(const char *, struct in_addr *, int, const char *, int,
     const int);
@@ -204,6 +206,7 @@
 	struct xinpcb *inp;
 	struct xinpgen *xig, *oxig;
 	struct xsocket *so;
+	int fnamelen, cnamelen;
 
 	istcp = 0;
 	switch (proto) {
@@ -236,6 +239,28 @@
 	if (!pcblist_sysctl(proto, name, &buf))
 		return;
 
+	if (cflag || Cflag) {
+		fnamelen = strlen("Stack");
+		cnamelen = strlen("CC");
+		oxig = xig = (struct xinpgen *)buf;
+		for (xig = (struct xinpgen*)((char *)xig + xig->xig_len);
+		    xig->xig_len > sizeof(struct xinpgen);
+		    xig = (struct xinpgen *)((char *)xig + xig->xig_len)) {
+			if (istcp) {
+				tp = (struct xtcpcb *)xig;
+				inp = &tp->xt_inp;
+			} else {
+				continue;
+			}
+			if (so->xso_protocol != proto)
+				continue;
+			if (inp->inp_gencnt > oxig->xig_gen)
+				continue;
+			fnamelen = max(fnamelen, (int)strlen(tp->xt_stack));
+			cnamelen = max(cnamelen, (int)strlen(tp->xt_cc));
+		}
+	}
+
 	oxig = xig = (struct xinpgen *)buf;
 	for (xig = (struct xinpgen *)((char *)xig + xig->xig_len);
 	    xig->xig_len > sizeof(struct xinpgen);
@@ -341,9 +366,19 @@
 				xo_emit("  {T:/%8.8s} {T:/%5.5s}",
 				    "flowid", "ftype");
 			}
+			if (cflag) {
+				xo_emit(" {T:/%-*.*s}",
+					fnamelen, fnamelen, "Stack");
+			}
 			if (Cflag)
-				xo_emit(" {T:/%-*.*s}", TCP_CA_NAME_MAX,
-				    TCP_CA_NAME_MAX, "CC");
+				xo_emit(" {T:/%-*.*s} {T:/%10.10s}"
+					" {T:/%10.10s} {T:/%5.5s}"
+					" {T:/%3.3s}", cnamelen,
+					cnamelen, "CC",
+					"cwin",
+					"ssthresh",
+					"MSS",
+					"ECN");
 			if (Pflag)
 				xo_emit(" {T:/%s}", "Log ID");
 			xo_emit("\n");
@@ -518,9 +553,24 @@
 			    inp->inp_flowtype);
 		}
 		if (istcp) {
+			if (cflag)
+				xo_emit(" {:stack/%-*.*s}",
+					
+					fnamelen, fnamelen, tp->xt_stack);
 			if (Cflag)
-				xo_emit(" {:cc/%-*.*s}", TCP_CA_NAME_MAX,
-				    TCP_CA_NAME_MAX, tp->xt_cc);
+				xo_emit(" {:cc/%-*.*s}"
+					" {:snd-cwnd/%10lu}"
+					" {:snd-ssthresh/%10lu}"
+					" {:t-maxseg/%5u} {:ecn/%3s}",
+					cnamelen, cnamelen, tp->xt_cc,
+					tp->t_snd_cwnd, tp->t_snd_ssthresh,
+					tp->t_maxseg,
+					(tp->t_state >= TCPS_ESTABLISHED ?
+					    (tp->xt_ecn > 0 ?
+						(tp->xt_ecn == 1 ?
+						    "ecn" : "ace")
+						: "off")
+					    : "n/a"));
 			if (Pflag)
 				xo_emit(" {:log-id/%s}",
 				    tp->xt_logid[0] == '\0' ?
Index: head/usr.bin/netstat/main.c
===================================================================
--- head/usr.bin/netstat/main.c
+++ head/usr.bin/netstat/main.c
@@ -205,7 +205,8 @@
 int	aflag;		/* show all sockets (including servers) */
 static int	Bflag;		/* show information about bpf consumers */
 int	bflag;		/* show i/f total bytes in/out */
-int	Cflag;		/* show congestion control */
+int	cflag;		/* show TCP congestion control stack */
+int	Cflag;		/* show congestion control algo and vars */
 int	dflag;		/* show i/f dropped packets */
 int	gflag;		/* show group (multicast) routing or stats */
 int	hflag;		/* show counters in human readable format */
@@ -251,7 +252,7 @@
 	if (argc < 0)
 		exit(EXIT_FAILURE);
 
-	while ((ch = getopt(argc, argv, "46AaBbCdF:f:ghI:iLlM:mN:nOoPp:Qq:RrSTsuWw:xz"))
+	while ((ch = getopt(argc, argv, "46AaBbCcdF:f:ghI:iLlM:mN:nOoPp:Qq:RrSTsuWw:xz"))
 	    != -1)
 		switch(ch) {
 		case '4':
@@ -280,6 +281,9 @@
 		case 'b':
 			bflag = 1;
 			break;
+		case 'c':
+			cflag = 1;
+			break;
 		case 'C':
 			Cflag = 1;
 			break;
@@ -886,7 +890,7 @@
 usage(void)
 {
 	(void)xo_error("%s\n%s\n%s\n%s\n%s\n%s\n%s\n%s\n%s\n%s\n%s\n%s\n",
-"usage: netstat [-46AaLnRSTWx] [-f protocol_family | -p protocol]\n"
+"usage: netstat [-46AaCcLnRSTWx] [-f protocol_family | -p protocol]\n"
 "               [-M core] [-N system]",
 "       netstat -i | -I interface [-46abdhnW] [-f address_family]\n"
 "               [-M core] [-N system]",
Index: head/usr.bin/netstat/netstat.h
===================================================================
--- head/usr.bin/netstat/netstat.h
+++ head/usr.bin/netstat/netstat.h
@@ -41,7 +41,8 @@
 extern int	Aflag;	/* show addresses of protocol control block */
 extern int	aflag;	/* show all sockets (including servers) */
 extern int	bflag;	/* show i/f total bytes in/out */
-extern int	Cflag;	/* show congestion control */
+extern int	cflag;	/* show congestion control stats */
+extern int	Cflag;	/* show congestion control algo and stack */
 extern int	dflag;	/* show i/f dropped packets */
 extern int	gflag;	/* show group (multicast) routing or stats */
 extern int	hflag;	/* show counters in human readable format */
Index: head/usr.bin/netstat/netstat.1
===================================================================
--- head/usr.bin/netstat/netstat.1
+++ head/usr.bin/netstat/netstat.1
@@ -28,7 +28,7 @@
 .\"	@(#)netstat.1	8.8 (Berkeley) 4/18/94
 .\" $FreeBSD$
 .\"
-.Dd September 13, 2020
+.Dd September 25, 2020
 .Dt NETSTAT 1
 .Os
 .Sh NAME
@@ -172,8 +172,10 @@
 .It Fl a
 Show the state of all sockets;
 normally sockets used by server processes are not shown.
+.It Fl c
+Show the used TCP stack for each session.
 .It Fl C
-Show the congestion control of TCP sockets.
+Show the congestion control algorithm and diagnostic information of TCP sockets.
 .It Fl L
 Show the size of the various listen queues.
 The first count shows the number of unaccepted connections,