diff --git a/libexec/ftpd/ftpd.8 b/libexec/ftpd/ftpd.8
index f3c4eeffa857..b995b8a164ad 100644
--- a/libexec/ftpd/ftpd.8
+++ b/libexec/ftpd/ftpd.8
@@ -43,6 +43,7 @@
 .Op Fl 46ADdEMmOoRrSUvW
 .Op Fl l Op Fl l
 .Op Fl a Ar address
+.Op Fl P Ar port
 .Op Fl p Ar file
 .Op Fl T Ar maxtimeout
 .Op Fl t Ar timeout
@@ -55,7 +56,9 @@ Internet File Transfer Protocol
 server process.  The server uses the
 .Tn TCP
 protocol
-and listens at the port specified in the
+and listens at the port specified with the
+.Fl P
+option or in the
 .Dq ftp
 service specification; see
 .Xr services 5 .
@@ -133,6 +136,14 @@ is also specified.
 .It Fl o
 Put server in write-only mode.
 RETR is disabled, preventing downloads.
+.It Fl P
+When
+.Fl D
+is specified, accept connections at
+.Ar port ,
+specified as a numeric value or service name, instead of at the default
+.Dq ftp
+port.
 .It Fl p
 When
 .Fl D
diff --git a/libexec/ftpd/ftpd.c b/libexec/ftpd/ftpd.c
index d59edd61eade..ca1e34852a35 100644
--- a/libexec/ftpd/ftpd.c
+++ b/libexec/ftpd/ftpd.c
@@ -115,6 +115,7 @@ union sockunion pasv_addr;
 
 int	daemon_mode;
 int	data;
+int	dataport;
 int	logged_in;
 struct	passwd *pw;
 int	ftpdebug;
@@ -277,6 +278,7 @@ main(int argc, char *argv[], char **envp)
 	FILE *fd;
 	int error;
 	char	*bindname = NULL;
+	const char *bindport = "ftp";
 	int	family = AF_UNSPEC;
 	int	enable_v4 = 0;
 	struct sigaction sa;
@@ -296,7 +298,7 @@ main(int argc, char *argv[], char **envp)
 #endif /* OLD_SETPROCTITLE */
 
 
-	while ((ch = getopt(argc, argv, "46a:AdDElmMoOp:rRSt:T:u:UvW")) != -1) {
+	while ((ch = getopt(argc, argv, "46a:AdDElmMoOp:P:rRSt:T:u:UvW")) != -1) {
 		switch (ch) {
 		case '4':
 			enable_v4 = 1;
@@ -352,6 +354,10 @@ main(int argc, char *argv[], char **envp)
 			pid_file = optarg;
 			break;
 
+		case 'P':
+			bindport = optarg;
+			break;
+
 		case 'r':
 			readonly = 1;
 			break;
@@ -436,11 +442,11 @@ main(int argc, char *argv[], char **envp)
 		hints.ai_socktype = SOCK_STREAM;
 		hints.ai_protocol = 0;
 		hints.ai_flags = AI_PASSIVE;
-		error = getaddrinfo(bindname, "ftp", &hints, &res);
+		error = getaddrinfo(bindname, bindport, &hints, &res);
 		if (error) {
 			if (family == AF_UNSPEC) {
 				hints.ai_family = AF_UNSPEC;
-				error = getaddrinfo(bindname, "ftp", &hints,
+				error = getaddrinfo(bindname, bindport, &hints,
 						    &res);
 			}
 		}
@@ -553,6 +559,7 @@ main(int argc, char *argv[], char **envp)
 		syslog(LOG_ERR, "getsockname (%s): %m",argv[0]);
 		exit(1);
 	}
+	dataport = ntohs(ctrl_addr.su_port) - 1; /* as per RFC 959 */
 #ifdef VIRTUAL_HOSTING
 	/* select our identity from virtual host table */
 	selecthost(&ctrl_addr);
@@ -1722,7 +1729,7 @@ getdatasock(char *mode)
 		syslog(LOG_WARNING, "data setsockopt (SO_REUSEADDR): %m");
 	/* anchor socket to avoid multi-homing problems */
 	data_source = ctrl_addr;
-	data_source.su_port = htons(20); /* ftp-data port */
+	data_source.su_port = htons(dataport);
 	for (tries = 1; ; tries++) {
 		if (bind(s, (struct sockaddr *)&data_source,
 		    data_source.su_len) >= 0)