diff --git a/src/client.c b/src/client.c
index 46a87ca..fc84c6d 100644
--- a/src/client.c
+++ b/src/client.c
@@ -94,8 +94,9 @@ static time_t max_timeout_ms;
 static time_t send_interval_ms;
 static time_t min_send_interval_ms;
 
-/* Server response timeout in ms */
+/* Server response timeout in ms and downstream window timeout */
 static time_t server_timeout_ms;
+static time_t downstream_timeout_ms;
 static int autodetect_server_timeout;
 
 /* Cumulative Round-Trip-Time in ms */
@@ -185,6 +186,7 @@ client_init()
 	rtt_total_ms = 1000;
 	send_interval_ms = 1000;
 	min_send_interval_ms = 1;
+	downstream_timeout_ms = 5000;
 
 	outbuf = NULL;
 	inbuf = NULL;
@@ -282,10 +284,11 @@ client_set_compression(int up, int down)
 }
 
 void
-client_set_dnstimeout(double timeout, double servertimeout, int autodetect)
+client_set_dnstimeout(double timeout, double servertimeout, double downfrag, int autodetect)
 {
 	max_timeout_ms = timeout * 1000;
 	server_timeout_ms = servertimeout * 1000;
+	downstream_timeout_ms = downfrag * 1000;
 	autodetect_server_timeout = autodetect;
 }
 
@@ -385,11 +388,13 @@ update_server_timeout(int dns_fd, int handshake)
 		server_timeout_ms = max_timeout_ms - rtt_ms;
 		if (server_timeout_ms <= 0) {
 			server_timeout_ms = 0;
-			fprintf(stderr, "Setting server timeout to 0 ms: if this continues try disabling lazy mode.\n");
+			fprintf(stderr, "Setting server timeout to 0 ms: if this continues try disabling lazy mode. (-L0)\n");
 		}
 	}
 
-	/* TODO: update window timeout */
+	/* update up/down window timeouts to something reasonable */
+	downstream_timeout_ms = rtt_ms * 2;
+	outbuf->timeout = ms_to_timeval(downstream_timeout_ms);
 
 	if (handshake) {
 		/* Send ping handshake to set server timeout */
@@ -626,7 +631,7 @@ send_packet(int fd, char cmd, const uint8_t *data, const size_t datalen)
 }
 
 int
-send_ping(int fd, int ping_response, int ack, int timeout)
+send_ping(int fd, int ping_response, int ack, int set_timeout)
 {
 	num_pings++;
 	if (conn == CONN_DNS_NULL) {
@@ -645,15 +650,17 @@ send_ping(int fd, int ping_response, int ack, int timeout)
 		}
 
 		*(uint16_t *) (data + 6) = htons(server_timeout_ms);
+		*(uint16_t *) (data + 8) = htons(downstream_timeout_ms);
 
-		/* update server lazy timeout, ack flag, respond with ping flag */
-		data[8] = ((timeout & 1) << 3) | ((ack < 0 ? 0 : 1) << 2) | (ping_response & 1);
-		data[9] = (rand_seed >> 8) & 0xff;
-		data[10] = (rand_seed >> 0) & 0xff;
+		/* update server frag/lazy timeout, ack flag, respond with ping flag */
+		data[10] = ((set_timeout & 1) << 4) | ((set_timeout & 1) << 3) | ((ack < 0 ? 0 : 1) << 2) | (ping_response & 1);
+		data[11] = (rand_seed >> 8) & 0xff;
+		data[12] = (rand_seed >> 0) & 0xff;
 		rand_seed += 263;
 
-		DEBUG(3, " SEND PING: respond %d, ack %d, server timeout %ld, flags %02X",
-					ping_response, ack, server_timeout_ms, data[8]);
+		DEBUG(3, " SEND PING: respond %d, ack %d, %s(server %ld ms, downfrag %ld ms), flags %02X",
+				ping_response, ack, set_timeout ? "SET " : "", server_timeout_ms,
+				downstream_timeout_ms, data[8]);
 
 		id = send_packet(fd, 'p', data, sizeof(data));
 
@@ -1014,7 +1021,7 @@ handshake_waitdns(int dns_fd, char *buf, size_t buflen, char cmd, int timeout)
 		if (r == 0)
 			return -3;	/* select timeout */
 
-		q.id = 0;
+		q.id = -1;
 		q.name[0] = '\0';
 		rv = read_dns_withq(dns_fd, 0, (uint8_t *)buf, buflen, &q);
 
@@ -1373,6 +1380,7 @@ client_tunnel(int tun_fd, int dns_fd)
 
 			if (sending > 0 || (total > 0 && lazymode)) {
 				tv = ms_to_timeval(min_send_interval_ms);
+				tv.tv_usec += 1;
 			} else if (total > 0 && !lazymode) {
 				/* use immediate mode send interval if nothing pending */
 				tv = ms_to_timeval(send_interval_ms);
@@ -1392,12 +1400,12 @@ client_tunnel(int tun_fd, int dns_fd)
 						num_recv - recv_since_report, (num_recv - recv_since_report) / stats);
 				fprintf(stderr, "  num IP rejected: %4lu,   untracked: %4lu,   lazy mode: %1d\n",
 						num_badip, num_untracked, lazymode);
-				fprintf(stderr, " Min send: %4ld ms, Avg RTT: %4ld ms, immediate replies: %5lu\n",
-						min_send_interval_ms, rtt_total_ms / num_immediate, num_immediate);
-				fprintf(stderr, " query timeouts: %4lu,    target: %4ld ms,   server: %4ld ms\n",
-						num_timeouts, max_timeout_ms, server_timeout_ms);
-				fprintf(stderr, " Resent fragments up: %4u,   downstream out of window: %4u\n",
-						outbuf->resends, inbuf->oos);
+				fprintf(stderr, " Min send: %5ld ms, Avg RTT: %5ld ms  Timeout server: %4ld ms\n",
+						min_send_interval_ms, rtt_total_ms / num_immediate, server_timeout_ms);
+				fprintf(stderr, " Queries immediate: %5lu, timed out: %4lu    target: %4ld ms\n",
+						num_immediate, num_timeouts, max_timeout_ms);
+				fprintf(stderr, " Frags resent: %4u,   OOS: %4u          down frag: %4ld ms\n",
+						outbuf->resends, inbuf->oos, downstream_timeout_ms);
 				fprintf(stderr, " TX fragments: %8lu"  ",   RX: %8lu"  ",   pings: %8lu"  "\n\n",
 						num_frags_sent, num_frags_recv, num_pings);
 
@@ -1568,8 +1576,8 @@ send_upenctest(int fd, char *s)
 	buf[3] = b32_5to8((rand_seed ) & 0x1f);
 	rand_seed++;
 
-	strncat(buf, s, 512);
-	strncat(buf, ".", 512);
+	strncat(buf, s, 512 - strlen(buf));
+	strncat(buf, ".", 512 - strlen(buf));
 	strncat(buf, topdomain, 512 - strlen(buf));
 	send_query(fd, (uint8_t *)buf);
 }
@@ -2573,6 +2581,7 @@ handshake_set_timeout(int dns_fd)
 		read = handshake_waitdns(dns_fd, in, sizeof(in), 'P', i + 1);
 		got_response(id, 1, 0);
 
+		fprintf(stderr, ".");
 		if (read > 0) {
 			if (strncmp("BADIP", in, 5) == 0) {
 				fprintf(stderr, "Server rejected sender IP address.\n");
@@ -2583,7 +2592,6 @@ handshake_set_timeout(int dns_fd)
 				break;
 		}
 
-		fprintf(stderr, ".");
 	}
 	if (!running)
 		return;
diff --git a/src/client.h b/src/client.h
index 198b150..92d4983 100644
--- a/src/client.h
+++ b/src/client.h
@@ -44,7 +44,7 @@ int client_set_qtype(char *qtype);
 char *client_get_qtype();
 void client_set_downenc(char *encoding);
 void client_set_compression(int up, int down);
-void client_set_dnstimeout(double, double, int);
+void client_set_dnstimeout(double, double, double, int);
 void client_set_lazymode(int lazy_mode);
 void client_set_windowsize(size_t, size_t);
 void client_set_hostname_maxlen(size_t i);
diff --git a/src/iodine.c b/src/iodine.c
index 76090d2..a7b96b3 100644
--- a/src/iodine.c
+++ b/src/iodine.c
@@ -70,7 +70,7 @@ print_usage()
 	extern char *__progname;
 
 	fprintf(stderr, "Usage: %s [-v] [-h] [-V sec] [-f] [-r] [-u user] [-t chrootdir] [-d device] "
-			"[-w downfrags] [-W upfrags] [-i sec] [-I sec] [-c 0|1] [-C 0|1] [-s ms] "
+			"[-w downfrags] [-W upfrags] [-i sec -j sec] [-I sec] [-c 0|1] [-C 0|1] [-s ms] "
 			"[-P password] [-m maxfragsize] [-M maxlen] [-T type] [-O enc] [-L 0|1] "
 			"[-z context] [-F pidfile] topdomain [nameserver1 [nameserver2 [nameserverN ...]]]\n", __progname);
 }
@@ -93,7 +93,7 @@ help()
 	fprintf(stderr, "     Base128, or (only for TXT:) Raw  (default: autodetect)\n");
 	fprintf(stderr, "  -I target interval between sending and receiving requests (default: 4 secs)\n");
 	fprintf(stderr, "      or ping interval in immediate mode (default: 1 sec)\n");
-	fprintf(stderr, "  -s minimum interval between queries (default: 1ms)\n");
+	fprintf(stderr, "  -s minimum interval between queries (default: 0ms)\n");
 	fprintf(stderr, "  -L 1: use lazy mode for low-latency (default). 0: don't (implies -I1)\n");
 	fprintf(stderr, "  -m max size of downstream fragments (default: autodetect)\n");
 	fprintf(stderr, "  -M max size of upstream hostnames (~100-255, default: 255)\n");
@@ -101,11 +101,12 @@ help()
 	fprintf(stderr, "  -P password used for authentication (max 32 chars will be used)\n\n");
 
 	fprintf(stderr, "Fine-tuning options:\n");
-	fprintf(stderr, "  -w downstream fragment window size (default: 8)\n");
-	fprintf(stderr, "  -W upstream fragment window size (default: 8)\n");
+	fprintf(stderr, "  -w downstream fragment window size (default: 8 frags)\n");
+	fprintf(stderr, "  -W upstream fragment window size (default: 8 frags)\n");
 	fprintf(stderr, "  -i server-side request timeout in lazy mode (default: auto)\n");
+	fprintf(stderr, "  -j downstream fragment ACK timeout, implies -i4 (default: 2 sec)\n");
 	fprintf(stderr, "  -c 1: use downstream compression (default), 0: disable\n");
-	fprintf(stderr, "  -C 1: use upstream compression, 0: disable (default)\n\n");
+	fprintf(stderr, "  -C 1: use upstream compression (default), 0: disable\n\n");
 
 	fprintf(stderr, "Other options:\n");
 	fprintf(stderr, "  -v to print version info and exit\n");
@@ -162,6 +163,7 @@ main(int argc, char **argv)
 	int lazymode;
 	double target_interval_sec;
 	double server_timeout_sec;
+	double downstream_timeout_sec;
 	int min_interval_ms;
 	int autodetect_server_timeout;
 	int up_compression;
@@ -183,6 +185,7 @@ main(int argc, char **argv)
 	int nameservaddr_len;
 	int nameserv_family;
 
+	/* Set default values */
 	nameserv_addrs_len = 0;
 	nameservaddr_len = 0;
 	nameserv_host = NULL;
@@ -208,12 +211,13 @@ main(int argc, char **argv)
 	raw_mode = 1;
 	lazymode = 1;
 	target_interval_sec = 5;	/* DNS RFC says 5 seconds minimum */
-	min_interval_ms = 1;
+	min_interval_ms = 0;
 	server_timeout_sec = 4;	/* Safe value for RTT <1s */
+	downstream_timeout_sec = 2;
 	autodetect_server_timeout = 1;
 	hostname_maxlen = 0xFF;
 	nameserv_family = AF_UNSPEC;
-	up_compression = 0;
+	up_compression = 1;
 	down_compression = 1;
 
 	up_windowsize = 8;
@@ -234,7 +238,7 @@ main(int argc, char **argv)
 		__progname++;
 #endif
 
-	while ((choice = getopt(argc, argv, "46vfDhrs:V:c:C:i:u:t:d:R:P:w:W:m:M:F:T:O:L:I:")) != -1) {
+	while ((choice = getopt(argc, argv, "46vfDhrs:V:c:C:i:j:u:t:d:R:P:w:W:m:M:F:T:O:L:I:")) != -1) {
 		switch(choice) {
 		case '4':
 			nameserv_family = AF_INET;
@@ -315,24 +319,25 @@ main(int argc, char **argv)
 				lazymode = 1;
 			if (lazymode < 0)
 				lazymode = 0;
-			if (!lazymode && target_interval_sec > 1)
-				target_interval_sec = 1;
 			break;
 		case 'I':
 			target_interval_sec = strtod(optarg, NULL);
-			if (target_interval_sec < 1)
-				target_interval_sec = 1;
 			break;
 		case 'i':
 			server_timeout_sec = strtod(optarg, NULL);
-			if (server_timeout_sec < 0.4)
-				server_timeout_sec = 0.4;
 			autodetect_server_timeout = 0;
 			break;
+		case 'j':
+			downstream_timeout_sec = strtod(optarg, NULL);
+			if (autodetect_server_timeout) {
+				autodetect_server_timeout = 0;
+				server_timeout_sec = 4;
+			}
+			break;
 		case 's':
 			min_interval_ms = atoi(optarg);
-			if (min_interval_ms < 1)
-				min_interval_ms = 1;
+			if (min_interval_ms < 0)
+				min_interval_ms = 0;
 		case 'w':
 			down_windowsize = atoi(optarg);
 			break;
@@ -418,8 +423,28 @@ main(int argc, char **argv)
 		usage();
 	}
 
+	if (target_interval_sec < 0.1) {
+		warnx("Target interval must be greater than 0.1 seconds!");
+		usage();
+	}
+
+	if (server_timeout_sec < 0.1 || server_timeout_sec >= target_interval_sec) {
+		warnx("Server timeout must be greater than 0.1 sec and less than target interval!");
+		usage();
+	}
+
+	if (downstream_timeout_sec < 0.1) {
+		warnx("Downstream fragment timeout must be more than 0.1 sec to prevent excessive retransmits.");
+		usage();
+	}
+
+	if (!lazymode && target_interval_sec > 1) {
+		warnx("Warning: Target interval of >1 second in immediate mode will cause high latency.");
+		usage();
+	}
+
 	client_set_compression(up_compression, down_compression);
-	client_set_dnstimeout(target_interval_sec, server_timeout_sec, autodetect_server_timeout);
+	client_set_dnstimeout(target_interval_sec, server_timeout_sec, downstream_timeout_sec, autodetect_server_timeout);
 	client_set_interval(target_interval_sec * 1000.0, min_interval_ms);
 	client_set_lazymode(lazymode);
 	client_set_topdomain(topdomain);