--- a/sshd.c
+++ b/sshd.c
@@ -1420,6 +1420,8 @@ server_accept_loop(struct ssh *ssh, int
 				    options.log_level,
 				    options.log_facility,
 				    log_stderr);
+
+				set_log_session_id();  // Set log session ID for this session
 				if (rexec_flag)
 					close(config_s[0]);
 				else {
--- a/log.c
+++ b/log.c
@@ -410,17 +410,17 @@ do_log(LogLevel level, int force, const
 		tmp_handler(level, force, fmtbuf, log_handler_ctx);
 		log_handler = tmp_handler;
 	} else if (log_on_stderr) {
-		snprintf(msgbuf, sizeof msgbuf, "%.*s\r\n",
-		    (int)sizeof msgbuf - 3, fmtbuf);
+		snprintf(msgbuf, sizeof msgbuf, "%.*s session=%s\r\n",
+		    (int)sizeof msgbuf - 3, fmtbuf, get_log_session_id());
 		(void)write(log_stderr_fd, msgbuf, strlen(msgbuf));
 	} else {
 #if defined(HAVE_OPENLOG_R) && defined(SYSLOG_DATA_INIT)
 		openlog_r(argv0 ? argv0 : __progname, LOG_PID, log_facility, &sdata);
-		syslog_r(pri, &sdata, "%.500s", fmtbuf);
+		syslog_r(pri, &sdata, "%.500s session=%s", fmtbuf, get_log_session_id());
 		closelog_r(&sdata);
 #else
 		openlog(argv0 ? argv0 : __progname, LOG_PID, log_facility);
-		syslog(pri, "%.500s", fmtbuf);
+		syslog(pri, "%.500s session=%s", fmtbuf, get_log_session_id());
 		closelog();
 #endif
 	}
@@ -452,6 +452,33 @@ sshlogdie(const char *file, const char *
 }
 
 void
+set_log_session_id()
+{
+        struct timeval tv;
+        char hostname[HOST_NAME_MAX + 1];
+        char session_id[HOST_NAME_MAX + 20];
+        char *s;
+        if (gethostname(hostname, sizeof(hostname)) != 0) {
+                *hostname = '\0';
+        }
+        gettimeofday(&tv, NULL);
+        snprintf(session_id, sizeof(session_id), "%s:%x.%x",
+                 hostname, tv.tv_sec, tv.tv_usec);
+        setenv("LOG_SESSION_ID", session_id, 1);
+}
+
+const char *
+get_log_session_id()
+{
+        const char *id = getenv("LOG_SESSION_ID");
+        if (!id) {
+                 set_log_session_id();
+                 id = getenv("LOG_SESSION_ID");
+        }
+        return id;
+}
+
+void
 sshsigdie(const char *file, const char *func, int line, int showfunc,
     LogLevel level, const char *suffix, const char *fmt, ...)
 {
--- /dev/null
+++ b/regress/session-id.sh
@@ -0,0 +1,23 @@
+tid="session id"
+
+start_sshd
+
+${SSH} -F $OBJ/ssh_config somehost true
+if [ $? -ne 0 ]; then
+	fail "ssh connect with failed"
+fi
+
+expected="session=$(hostname)"
+
+# grab the first session ID which will be stable across session
+sessionid=$(grep -m1 $expected $TEST_SSHD_LOGFILE | sed -E 's/.*(session=.*)/\1/')
+
+line_count=$(grep -c $expected $TEST_SSHD_LOGFILE)
+if [ $line_count == "0" ]; then
+	fail "No session ID lines found"
+fi
+
+stable_id_count=$(grep -c $sessionid $TEST_SSHD_LOGFILE)
+if [ $line_count != $stable_id_count ]; then
+	fail 'Mismatching session ids found'
+fi
--- a/log.h
+++ b/log.h
@@ -68,6 +68,9 @@ const char *	log_level_name(LogLevel);
 void	 set_log_handler(log_handler_fn *, void *);
 void	 cleanup_exit(int) __attribute__((noreturn));
 
+void		set_log_session_id();
+const char *	get_log_session_id();
+
 void	 sshlog(const char *, const char *, int, int,
     LogLevel, const char *, const char *, ...)
     __attribute__((format(printf, 7, 8)));
--- a/session.c
+++ b/session.c
@@ -1256,6 +1256,10 @@ do_setup_env(struct ssh *ssh, Session *s
 		child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND",
 		    original_command);
 
+  /* set LOG_SESSION_ID for child */
+  child_set_env(&env, &envsize, "LOG_SESSION_ID", get_log_session_id());
+  debug("set LOG_SESION_ID to: %s", get_log_session_id());
+
 	if (debug_flag) {
 		/* dump the environment */
 		fprintf(stderr, "Environment:\n");