diff --git a/packet.c b/packet.c
index 6b9d3525b..94e8460ca 100644
--- a/packet.c
+++ b/packet.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: packet.c,v 1.244 2017/02/03 02:56:00 dtucker Exp $ */
+/* $OpenBSD: packet.c,v 1.245 2017/02/03 23:03:33 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -352,6 +352,25 @@ ssh_packet_get_mux(struct ssh *ssh)
 	return ssh->state->mux;
 }
 
+int
+ssh_packet_set_log_preamble(struct ssh *ssh, const char *fmt, ...)
+{
+	va_list args;
+	int r;
+
+	free(ssh->log_preamble);
+	if (fmt == NULL)
+		ssh->log_preamble = NULL;
+	else {
+		va_start(args, fmt);
+		r = vasprintf(&ssh->log_preamble, fmt, args);
+		va_end(args);
+		if (r < 0 || ssh->log_preamble == NULL)
+			return SSH_ERR_ALLOC_FAIL;
+	}
+	return 0;
+}
+
 int
 ssh_packet_stop_discard(struct ssh *ssh)
 {
@@ -2074,27 +2093,36 @@ ssh_packet_send_debug(struct ssh *ssh, const char *fmt,...)
 		fatal("%s: %s", __func__, ssh_err(r));
 }
 
+static void
+fmt_connection_id(struct ssh *ssh, char *s, size_t l)
+{
+	snprintf(s, l, "%.200s%s%s port %d",
+	    ssh->log_preamble ? ssh->log_preamble : "",
+	    ssh->log_preamble ? " " : "",
+	    ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
+}
+
 /*
  * Pretty-print connection-terminating errors and exit.
  */
 void
 sshpkt_fatal(struct ssh *ssh, const char *tag, int r)
 {
+	char remote_id[512];
+
+	fmt_connection_id(ssh, remote_id, sizeof(remote_id));
+
 	switch (r) {
 	case SSH_ERR_CONN_CLOSED:
-		logdie("Connection closed by %.200s port %d",
-		    ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
+		logdie("Connection closed by %s", remote_id);
 	case SSH_ERR_CONN_TIMEOUT:
-		logdie("Connection %s %.200s port %d timed out",
-		    ssh->state->server_side ? "from" : "to",
-		    ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
+		logdie("Connection %s %s timed out",
+		    ssh->state->server_side ? "from" : "to", remote_id);
 	case SSH_ERR_DISCONNECTED:
-		logdie("Disconnected from %.200s port %d",
-		    ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
+		logdie("Disconnected from %s", remote_id);
 	case SSH_ERR_SYSTEM_ERROR:
 		if (errno == ECONNRESET)
-			logdie("Connection reset by %.200s port %d",
-			    ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
+			logdie("Connection reset by %s", remote_id);
 		/* FALLTHROUGH */
 	case SSH_ERR_NO_CIPHER_ALG_MATCH:
 	case SSH_ERR_NO_MAC_ALG_MATCH:
@@ -2102,17 +2130,16 @@ sshpkt_fatal(struct ssh *ssh, const char *tag, int r)
 	case SSH_ERR_NO_KEX_ALG_MATCH:
 	case SSH_ERR_NO_HOSTKEY_ALG_MATCH:
 		if (ssh && ssh->kex && ssh->kex->failed_choice) {
-			logdie("Unable to negotiate with %.200s port %d: %s. "
-			    "Their offer: %s", ssh_remote_ipaddr(ssh),
-			    ssh_remote_port(ssh), ssh_err(r),
+			logdie("Unable to negotiate with %s: %s. "
+			    "Their offer: %s", remote_id, ssh_err(r),
 			    ssh->kex->failed_choice);
 		}
 		/* FALLTHROUGH */
 	default:
-		logdie("%s%sConnection %s %.200s port %d: %s",
+		logdie("%s%sConnection %s %s: %s",
 		    tag != NULL ? tag : "", tag != NULL ? ": " : "",
 		    ssh->state->server_side ? "from" : "to",
-		    ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), ssh_err(r));
+		    remote_id, ssh_err(r));
 	}
 }
 
@@ -2125,7 +2152,7 @@ sshpkt_fatal(struct ssh *ssh, const char *tag, int r)
 void
 ssh_packet_disconnect(struct ssh *ssh, const char *fmt,...)
 {
-	char buf[1024];
+	char buf[1024], remote_id[512];
 	va_list args;
 	static int disconnecting = 0;
 	int r;
@@ -2138,12 +2165,13 @@ ssh_packet_disconnect(struct ssh *ssh, const char *fmt,...)
 	 * Format the message.  Note that the caller must make sure the
 	 * message is of limited size.
 	 */
+	fmt_connection_id(ssh, remote_id, sizeof(remote_id));
 	va_start(args, fmt);
 	vsnprintf(buf, sizeof(buf), fmt, args);
 	va_end(args);
 
 	/* Display the error locally */
-	logit("Disconnecting: %.100s", buf);
+	logit("Disconnecting %s: %.100s", remote_id, buf);
 
 	/*
 	 * Send the disconnect message to the other side, and wait
diff --git a/packet.h b/packet.h
index c33dd17df..0d25b352c 100644
--- a/packet.h
+++ b/packet.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: packet.h,v 1.75 2017/02/03 02:56:00 dtucker Exp $ */
+/* $OpenBSD: packet.h,v 1.76 2017/02/03 23:03:33 djm Exp $ */
 
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
@@ -62,6 +62,9 @@ struct ssh {
 	char *local_ipaddr;
 	int local_port;
 
+	/* Optional preamble for log messages (e.g. username) */
+	char *log_preamble;
+
 	/* Dispatcher table */
 	dispatch_fn *dispatch[DISPATCH_MAX];
 	/* number of packets to ignore in the dispatcher */
@@ -104,6 +107,8 @@ void     ssh_packet_set_server(struct ssh *);
 void     ssh_packet_set_authenticated(struct ssh *);
 void     ssh_packet_set_mux(struct ssh *);
 int	 ssh_packet_get_mux(struct ssh *);
+int	 ssh_packet_set_log_preamble(struct ssh *, const char *, ...)
+    __attribute__((format(printf, 2, 3)));
 
 int	 ssh_packet_log_type(u_char);