diff --git a/src/ftppr.c b/src/ftppr.c
index 609f904..049bc93 100644
--- a/src/ftppr.c
+++ b/src/ftppr.c
@@ -64,6 +64,13 @@ void * ftpprchild(struct clientparam* param) {
 
 	}
 	else if (!strncasecmp((char *)buf, "PASS ", 5)){
+		/* The user name carries the server to log in to, and it arrives
+		   with USER. Without it there is nothing to log in to, and what
+		   follows would read the name and the host as if there were. */
+		if(!param->hostname || !param->extusername){
+			socksend(param, param->ctrlsock, (unsigned char *)"503 Login with USER first\r\n", 27, conf.timeouts[STRING_S]);
+			RETURN(805);
+		}
 		param->extpassword = (unsigned char *)strdup((char *)buf+5);
 		inbuf = BUFSIZE;
 		res = ftplogin(param, (char *)buf, &inbuf);
diff --git a/src/smtpp.c b/src/smtpp.c
index e82200e..3905bf0 100644
--- a/src/smtpp.c
+++ b/src/smtpp.c
@@ -159,7 +159,10 @@ void * smtppchild(struct clientparam* param) {
 	i = de64(buf,username,255);
 	if(i < 1) {RETURN(664);}
 	username[i] = 0;
-	parseconnusername((char *)username, param, 0, 587);
+	/* The name has to carry the host to connect to, and the answer says
+	   whether it did: without one there is nowhere to go, and what follows
+	   reads the name as if there were. */
+	if(parseconnusername((char *)username, param, 0, 587)) {RETURN(669);}
 	socksend(param, param->clisock, (unsigned char *)"334 UGFzc3dvcmQ6\r\n", 18,conf.timeouts[STRING_S]);	
 	i = sockgetlinebuf(param, CLIENT, buf, sizeof(buf) - 10, '\n', conf.timeouts[STRING_S]);
 	if(i < 2) {RETURN(665);}
@@ -184,7 +187,7 @@ void * smtppchild(struct clientparam* param) {
 	}
 	if(i < 3 || *username) {RETURN(668);}
 	username[i] = 0;
-	parseconnusername((char *)username+1, param, 0, 587);
+	if(parseconnusername((char *)username+1, param, 0, 587)) {RETURN(670);}
 	res = (int)strlen((char *)username+1) + 2;
 	if(res < i){
 		if(param->extpassword) free(param->extpassword);
diff --git a/tests/harness.py b/tests/harness.py
index 8912b69..163255b 100644
--- a/tests/harness.py
+++ b/tests/harness.py
@@ -22,6 +22,7 @@ configurations it needs, starts them, and states what it expects:
 import base64
 import http.client
 import os
+import random
 import shutil
 import socket
 import ssl
@@ -33,6 +34,11 @@ import threading
 import time
 
 
+# Ports handed out in this run: a service which has finished may still be
+# in TIME_WAIT, and another case binding the same port would fail for it.
+_PORTS_TAKEN = set()
+
+
 class Response:
     """A reply, or the reason there wasn't one."""
 
@@ -146,14 +152,30 @@ class Tester:
             sock.close()
 
     def free_port(self):
-        """A port nothing is listening on. Closed again before it is used,
-        which is racy in principle and reliable enough in practice."""
-        s = socket.socket()
-        try:
-            s.bind(("127.0.0.1", 0))
-            return s.getsockname()[1]
-        finally:
-            s.close()
+        """A port nothing is listening on, and nothing is likely to take.
+
+        Asking the system for an ephemeral port hands back one out of the
+        range it also draws outgoing connections from - 32768 up on Linux,
+        49152 up on Windows - so between the check here and the bind in the
+        service, a connection somewhere else in the suite can take it. That
+        shows up as a service which never listens, or a bind() error deep in
+        a case which has nothing to do with ports. Ports are taken from below
+        both ranges instead, and none is handed out twice in a run.
+        """
+        for _ in range(200):
+            port = random.randint(10000, 19999)
+            if port in _PORTS_TAKEN:
+                continue
+            sock = socket.socket()
+            try:
+                sock.bind(("127.0.0.1", port))
+            except OSError:
+                continue
+            finally:
+                sock.close()
+            _PORTS_TAKEN.add(port)
+            return port
+        raise RuntimeError("no free port in the range the suite uses")
 
     def write_config(self, name, config):
         path = os.path.join(self.tmpdir, name + ".cfg")