diff --git a/contrib/traceroute/traceroute.8 b/contrib/traceroute/traceroute.8
index 85a7e9d3a17..21427ef6e97 100644
--- a/contrib/traceroute/traceroute.8
+++ b/contrib/traceroute/traceroute.8
@@ -16,7 +16,7 @@
 .\"	$Id: traceroute.8,v 1.19 2000/09/21 08:44:19 leres Exp $
 .\"	$FreeBSD$
 .\"
-.Dd November 25, 2020
+.Dd October 25, 2023
 .Dt TRACEROUTE 8
 .Os
 .Sh NAME
@@ -25,7 +25,7 @@
 .Sh SYNOPSIS
 .Nm
 .Bk -words
-.Op Fl adDeFISnrvx
+.Op Fl adDeEFISnrvx
 .Op Fl f Ar first_ttl
 .Op Fl g Ar gateway
 .Op Fl M Ar first_ttl
@@ -67,6 +67,22 @@ default.
 Firewall evasion mode.
 Use fixed destination ports for UDP, UDP-Lite, TCP and SCTP probes.
 The destination port does NOT increment with each packet sent.
+.It Fl E
+Detect ECN bleaching.
+Set the
+.Em IPTOS_ECN_ECT1
+Explicit Congestion Notification (ECN) bits
+.Pq Dv 01 ,
+and report if the hop has bleached
+.Pq Dv 00
+or mangled
+.Pq Dv 10
+them, or if it is experiencing congestion
+.Pq Dv 11 .
+Otherwise, report that it passed the bits appropriately.
+If
+.Fl t
+is also specified, the corresponding ECN bits will be replaced.
 .It Fl f Ar first_ttl
 Set the initial time-to-live used in the first outgoing probe packet.
 .It Fl F
diff --git a/contrib/traceroute/traceroute.c b/contrib/traceroute/traceroute.c
index fc87575ea04..6f2350150bd 100644
--- a/contrib/traceroute/traceroute.c
+++ b/contrib/traceroute/traceroute.c
@@ -365,6 +365,7 @@ int doipcksum = 1;		/* calculate ip checksums by default */
 int optlen;			/* length of ip options */
 int fixedPort = 0;		/* Use fixed destination port for TCP and UDP */
 int printdiff = 0;		/* Print the difference between sent and quoted */
+int ecnflag = 0;		/* ECN bleaching detection flag */
 
 extern int optind;
 extern int opterr;
@@ -597,7 +598,7 @@ main(int argc, char **argv)
 		prog = argv[0];
 
 	opterr = 0;
-	while ((op = getopt(argc, argv, "aA:edDFInrSvxf:g:i:M:m:P:p:q:s:t:w:z:")) != EOF)
+	while ((op = getopt(argc, argv, "aA:eEdDFInrSvxf:g:i:M:m:P:p:q:s:t:w:z:")) != EOF)
 		switch (op) {
 		case 'a':
 			as_path = 1;
@@ -620,6 +621,10 @@ main(int argc, char **argv)
 			fixedPort = 1;
 			break;
 
+		case 'E':
+			ecnflag = 1;
+			break;
+
 		case 'f':
 		case 'M':	/* FreeBSD compat. */
 			first_ttl = str2val(optarg, "first ttl", 1, 255);
@@ -784,6 +789,10 @@ main(int argc, char **argv)
 	outip->ip_v = IPVERSION;
 	if (settos)
 		outip->ip_tos = tos;
+	if (ecnflag) {
+		outip->ip_tos &= ~IPTOS_ECN_MASK;
+		outip->ip_tos |= IPTOS_ECN_ECT1;
+	}
 #ifdef BYTESWAP_IP_HDR
 	outip->ip_len = htons(packlen);
 	outip->ip_off = htons(off);
@@ -1122,6 +1131,23 @@ main(int argc, char **argv)
 #endif
 					precis = 3;
 				Printf("  %.*f ms", precis, T);
+				if (ecnflag) {
+					u_char ecn = hip->ip_tos & IPTOS_ECN_MASK;
+					switch (ecn) {
+					case IPTOS_ECN_ECT1:
+						Printf(" (ecn=passed)");
+						break;
+					case IPTOS_ECN_NOTECT:
+						Printf(" (ecn=bleached)");
+						break;
+					case IPTOS_ECN_CE:
+						Printf(" (ecn=congested)");
+						break;
+					default:
+						Printf(" (ecn=mangled)");
+						break;
+					}
+				}
 				if (printdiff) {
 					Printf("\n");
 					Printf("%*.*s%s\n",
@@ -2126,7 +2152,7 @@ usage(void)
 
 	Fprintf(stderr, "Version %s\n", version);
 	Fprintf(stderr,
-	    "Usage: %s [-adDeFInrSvx] [-f first_ttl] [-g gateway] [-i iface]\n"
+	    "Usage: %s [-adDeEFInrSvx] [-f first_ttl] [-g gateway] [-i iface]\n"
 	    "\t[-m max_ttl] [-p port] [-P proto] [-q nqueries] [-s src_addr]\n"
 	    "\t[-t tos] [-w waittime] [-A as_server] [-z pausemsecs] host [packetlen]\n", prog);
 	exit(1);