diff --git a/CHANGES b/CHANGES
index 60deebf..1da4617 100644
--- a/CHANGES
+++ b/CHANGES
@@ -28,6 +28,13 @@ Coding:
 
 	Make gcc happy, replace strncat with "manual" copying
 
+	On addresses like UDP-RECVFROM with fork option every packet causes a
+	new child process which then reads the packet. The parent process must
+	wait until the packet has been read before checking again. The former
+	synchronization mechanism using SIGUSR1 is now replaced by a
+	socketpair. SIGUSR1 is no longer used for internal synchronization.
+	Tests: UDP4_FORK UDP6_FORK UNIX_FORK
+
 ####################### V 1.7.4.5 (not released):
 
 Corrections:
diff --git a/socat.c b/socat.c
index 873920c..6488103 100644
--- a/socat.c
+++ b/socat.c
@@ -720,6 +720,7 @@ int socat(const char *address1, const char *address2) {
 	       the communication channel, so continue */
 	    Info2("child "F_pid" has already died with status %d",
 		  XIO_RDSTREAM(sock1)->para.exec.pid, statunknown[i]);
+	    ++num_child; 	/* it was counted as anonymous child, undo */
 	    if (statunknown[i] != 0) {
 	       return 1;
 	    }
diff --git a/test.sh b/test.sh
index 93ea5c8..0cb66b5 100755
--- a/test.sh
+++ b/test.sh
@@ -1935,7 +1935,7 @@ testaddrs () {
     local a A;
     for a in $@; do
 	A=$(echo "$a" |tr 'a-z' 'A-Z')
-	if ! $SOCAT $A /dev/null 2>&1 |grep -q "E unknown device/address"; then
+	if ! $SOCAT $A /dev/null 2>&1 </dev/null |grep -q "E unknown device/address"; then
 	    shift
 	    continue
 	fi
@@ -1991,7 +1991,8 @@ childpids () {
     AIX)     l="$(ps -fade |grep "^........ ...... $(printf %6u $1)" |awk '{print($2);}')" ;;
     FreeBSD) l="$(ps -fl   |grep "^[^ ][^ ]*[ ][ ]*[0-9][0-9]*[ ][ ]*$(printf %5u $1)" |awk '{print($2);}')" ;;
     HP-UX)   l="$(ps -fade |grep "^........ ..... $(printf %5u $1)" |awk '{print($2);}')" ;;
-    Linux)   l="$(ps -fade |grep "^........ ..... $(printf %5u $1)" |awk '{print($2);}')" ;;
+#    Linux)   l="$(ps -fade |grep "^........ ..... $(printf %5u $1)" |awk '{print($2);}')" ;;
+    Linux)   l="$(ps -fade |grep "^[^[:space:]][^[:space:]]*[[:space:]][[:space:]]*[^[:space:]][^[:space:]]*[[:space:]][[:space:]]*$1 " |awk '{print($2);}')" ;;
 #    NetBSD)  l="$(ps -aj   |grep "^........ ..... $(printf %4u $1)" |awk '{print($2);}')" ;;
     NetBSD)  l="$(ps -aj   |grep "^[^ ][^ ]*[ ][ ]*..... $(printf %5u $1)" |awk '{print($2);}')" ;;
     OpenBSD) l="$(ps -aj   |grep "^........ ..... $(printf %5u $1)" |awk '{print($2);}')" ;;
@@ -5593,7 +5594,7 @@ N=$((N+1))
 
 NAME=OUTBOUNDIN
 case "$TESTS" in
-*%$N%*|*%functions%*|*%openssl%*|*%proxy%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%openssl%*|*%proxy%*|*%fork%*|*%$NAME%*)
 TEST="$NAME: gender changer via SSL through HTTP proxy, oneshot"
 if ! eval $NUMCOND; then :;
 elif ! feat=$(testfeats openssl proxy); then
@@ -5684,7 +5685,7 @@ N=$((N+1))
 #!
 NAME=INTRANETRIPPER
 case "$TESTS" in
-*%$N%*|*%functions%*|*%openssl%*|*%proxy%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%openssl%*|*%proxy%*|*%fork%*|*%$NAME%*)
 TEST="$NAME: gender changer via SSL through HTTP proxy, daemons"
 if ! eval $NUMCOND; then :;
 elif ! feat=$(testfeats openssl proxy); then
@@ -5966,7 +5967,7 @@ testserversec () {
 
 NAME=TCP4RANGEBITS
 case "$TESTS" in
-*%$N%*|*%functions%*|*%security%*|*%tcp%*|*%tcp4%*|*%ip4%*|*%range%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%security%*|*%tcp%*|*%tcp4%*|*%ip4%*|*%range%*|*%fork%*|*%$NAME%*)
 TEST="$NAME: security of TCP4-L with RANGE option"
 if ! eval $NUMCOND; then :;
 elif [ -z "$SECONDADDR" ]; then
@@ -5983,7 +5984,7 @@ N=$((N+1))
 
 NAME=TCP4RANGEMASK
 case "$TESTS" in
-*%$N%*|*%functions%*|*%security%*|*%tcp%*|*%tcp4%*|*%ip4%*|*%range%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%security%*|*%tcp%*|*%tcp4%*|*%ip4%*|*%range%*|*%fork%*|*%$NAME%*)
 TEST="$NAME: security of TCP4-L with RANGE option"
 if ! eval $NUMCOND; then :;
 elif [ -z "$SECONDADDR" ]; then
@@ -6001,7 +6002,7 @@ N=$((N+1))
 # like TCP4RANGEMASK, but the "bad" address is within the same class A network
 NAME=TCP4RANGEMASKHAIRY
 case "$TESTS" in
-*%$N%*|*%functions%*|*%security%*|*%tcp%*|*%tcp4%*|*%ip4%*|*%range%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%fork%*|*%security%*|*%tcp%*|*%tcp4%*|*%ip4%*|*%range%*|*%$NAME%*)
 TEST="$NAME: security of TCP4-L with RANGE option"
 if ! eval $NUMCOND; then :; else
 newport tcp4 	# provide free port number in $PORT
@@ -6013,7 +6014,7 @@ N=$((N+1))
 
 NAME=TCP4SOURCEPORT
 case "$TESTS" in
-*%$N%*|*%functions%*|*%security%*|*%tcp%*|*%tcp4%*|*%ip4%*|*%sourceport%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%fork%*|*%security%*|*%tcp%*|*%tcp4%*|*%ip4%*|*%sourceport%*|*%$NAME%*)
 TEST="$NAME: security of TCP4-L with SOURCEPORT option"
 if ! eval $NUMCOND; then :; else
 newport tcp4 	# provide free port number in $PORT
@@ -6024,7 +6025,7 @@ N=$((N+1))
 
 NAME=TCP4LOWPORT
 case "$TESTS" in
-*%$N%*|*%functions%*|*%security%*|*%tcp%*|*%tcp4%*|*%ip4%*|*%lowport%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%fork%*|*%security%*|*%tcp%*|*%tcp4%*|*%ip4%*|*%lowport%*|*%$NAME%*)
 TEST="$NAME: security of TCP4-L with LOWPORT option"
 if ! eval $NUMCOND; then :; else
 newport tcp4 	# provide free port number in $PORT
@@ -6035,7 +6036,7 @@ N=$((N+1))
 
 NAME=TCP4WRAPPERS_ADDR
 case "$TESTS" in
-*%$N%*|*%functions%*|*%security%*|*%tcp%*|*%tcp4%*|*%ip4%*|*%tcpwrap%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%fork%*|*%security%*|*%tcp%*|*%tcp4%*|*%ip4%*|*%tcpwrap%*|*%$NAME%*)
 TEST="$NAME: security of TCP4-L with TCPWRAP option"
 if ! eval $NUMCOND; then :;
 elif ! feat=$(testfeats tcp ip4 libwrap) || ! runsip4 >/dev/null; then
@@ -6055,7 +6056,7 @@ N=$((N+1))
 
 NAME=TCP4WRAPPERS_NAME
 case "$TESTS" in
-*%$N%*|*%functions%*|*%security%*|*%tcp%*|*%tcp4%*|*%ip4%*|*%tcpwrap%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%fork%*|*%security%*|*%tcp%*|*%tcp4%*|*%ip4%*|*%tcpwrap%*|*%$NAME%*)
 TEST="$NAME: security of TCP4-L with TCPWRAP option"
 if ! eval $NUMCOND; then :;
 elif ! feat=$(testfeats tcp ip4 libwrap) || ! runsip4 >/dev/null; then
@@ -6076,7 +6077,7 @@ N=$((N+1))
 
 NAME=TCP6RANGE
 case "$TESTS" in
-*%$N%*|*%functions%*|*%security%*|*%tcp%*|*%tcp6%*|*%ip6%*|*%range%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%fork%*|*%security%*|*%tcp%*|*%tcp6%*|*%ip6%*|*%range%*|*%$NAME%*)
 TEST="$NAME: security of TCP6-L with RANGE option"
 if ! eval $NUMCOND; then :;
 elif ! feat=$(testfeats tcp ip6) || ! runsip6 >/dev/null; then
@@ -6092,7 +6093,7 @@ N=$((N+1))
 
 NAME=TCP6SOURCEPORT
 case "$TESTS" in
-*%$N%*|*%functions%*|*%security%*|*%tcp%*|*%tcp6%*|*%ip6%*|*%sourceport%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%fork%*|*%security%*|*%tcp%*|*%tcp6%*|*%ip6%*|*%sourceport%*|*%$NAME%*)
 TEST="$NAME: security of TCP6-L with SOURCEPORT option"
 if ! eval $NUMCOND; then :;
 elif ! feat=$(testfeats tcp ip6) || ! runsip6 >/dev/null; then
@@ -6108,7 +6109,7 @@ N=$((N+1))
 
 NAME=TCP6LOWPORT
 case "$TESTS" in
-*%$N%*|*%functions%*|*%security%*|*%tcp%*|*%tcp6%*|*%ip6%*|*%lowport%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%fork%*|*%security%*|*%tcp%*|*%tcp6%*|*%ip6%*|*%lowport%*|*%$NAME%*)
 TEST="$NAME: security of TCP6-L with LOWPORT option"
 if ! eval $NUMCOND; then :;
 elif ! feat=$(testfeats tcp ip6) || ! runsip6 >/dev/null; then
@@ -6124,7 +6125,7 @@ N=$((N+1))
 
 NAME=TCP6TCPWRAP
 case "$TESTS" in
-*%$N%*|*%functions%*|*%security%*|*%tcp%*|*%tcp6%*|*%ip6%*|*%tcpwrap%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%fork%*|*%security%*|*%tcp%*|*%tcp6%*|*%ip6%*|*%tcpwrap%*|*%$NAME%*)
 TEST="$NAME: security of TCP6-L with TCPWRAP option"
 if ! eval $NUMCOND; then :;
 elif ! feat=$(testfeats tcp ip6 libwrap && runstcp6); then
@@ -6145,7 +6146,7 @@ N=$((N+1))
 
 NAME=UDP4RANGE
 case "$TESTS" in
-*%$N%*|*%functions%*|*%security%*|*%udp%*|*%udp4%*|*%ip4%*|*%range%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%security%*|*%fork%*|*%udp%*|*%udp4%*|*%ip4%*|*%range%*|*%$NAME%*)
 TEST="$NAME: security of UDP4-L with RANGE option"
 if ! eval $NUMCOND; then :; else
 newport udp4 	# provide free port number in $PORT
@@ -6200,7 +6201,7 @@ N=$((N+1))
 
 NAME=UDP6RANGE
 case "$TESTS" in
-*%$N%*|*%functions%*|*%security%*|*%udp%*|*%udp6%*|*%ip6%*|*%range%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%security%*|*%fork%*|*%udp%*|*%udp6%*|*%ip6%*|*%range%*|*%$NAME%*)
 TEST="$NAME: security of UDP6-L with RANGE option"
 if ! eval $NUMCOND; then :;
 elif ! feat=$(testfeats tcp ip6) || ! runsip6 >/dev/null; then
@@ -6269,7 +6270,7 @@ N=$((N+1))
 
 NAME=OPENSSLTCP4_RANGE
 case "$TESTS" in
-*%$N%*|*%functions%*|*%security%*|*%tcp%*|*%tcp4%*|*%ip4%*|*%openssl%*|*%range%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%security%*|*%fork%*|*%tcp%*|*%tcp4%*|*%ip4%*|*%openssl%*|*%range%*|*%$NAME%*)
 TEST="$NAME: security of SSL-L over TCP/IPv4 with RANGE option"
 if ! eval $NUMCOND; then :;
 elif ! testfeats openssl >/dev/null; then
@@ -6286,7 +6287,7 @@ N=$((N+1))
 
 NAME=OPENSSLTCP4_SOURCEPORT
 case "$TESTS" in
-*%$N%*|*%functions%*|*%security%*|*%tcp%*|*%tcp4%*|*%ip4%*|*%openssl%*|*%sourceport%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%security%*|*%fork%*|*%tcp%*|*%tcp4%*|*%ip4%*|*%openssl%*|*%sourceport%*|*%$NAME%*)
 TEST="$NAME: security of SSL-L with SOURCEPORT option"
 if ! eval $NUMCOND; then :;
 elif ! testfeats openssl >/dev/null; then
@@ -6303,7 +6304,7 @@ N=$((N+1))
 
 NAME=OPENSSLTCP4_LOWPORT
 case "$TESTS" in
-*%$N%*|*%functions%*|*%security%*|*%tcp%*|*%tcp4%*|*%ip4%*|*%openssl%*|*%lowport%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%security%*|*%fork%*|*%tcp%*|*%tcp4%*|*%ip4%*|*%openssl%*|*%lowport%*|*%$NAME%*)
 TEST="$NAME: security of SSL-L with LOWPORT option"
 if ! eval $NUMCOND; then :;
 elif ! testfeats openssl >/dev/null; then
@@ -6320,7 +6321,7 @@ N=$((N+1))
 
 NAME=OPENSSLTCP4_TCPWRAP
 case "$TESTS" in
-*%$N%*|*%functions%*|*%security%*|*%tcp%*|*%tcp4%*|*%ip4%*|*%openssl%*|*%tcpwrap%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%security%*|*%fork%*|*%tcp%*|*%tcp4%*|*%ip4%*|*%openssl%*|*%tcpwrap%*|*%$NAME%*)
 TEST="$NAME: security of SSL-L with TCPWRAP option"
 if ! eval $NUMCOND; then :;
 elif ! feat=$(testfeats ip4 tcp libwrap openssl); then
@@ -6341,7 +6342,7 @@ N=$((N+1))
 
 NAME=OPENSSLCERTSERVER
 case "$TESTS" in
-*%$N%*|*%functions%*|*%security%*|*%tcp%*|*%tcp4%*|*%ip4%*|*%openssl%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%security%*|*%fork%*|*%tcp%*|*%tcp4%*|*%ip4%*|*%openssl%*|*%$NAME%*)
 TEST="$NAME: security of SSL-L with client certificate"
 if ! eval $NUMCOND; then :;
 elif ! testfeats openssl >/dev/null; then
@@ -6359,7 +6360,7 @@ N=$((N+1))
 
 NAME=OPENSSLCERTCLIENT
 case "$TESTS" in
-*%$N%*|*%functions%*|*%security%*|*%tcp%*|*%tcp4%*|*%ip4%*|*%openssl%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%security%*|*%fork%*|*%tcp%*|*%tcp4%*|*%ip4%*|*%openssl%*|*%$NAME%*)
 TEST="$NAME: security of SSL with server certificate"
 if ! eval $NUMCOND; then :;
 elif ! testfeats openssl >/dev/null; then
@@ -6378,7 +6379,7 @@ N=$((N+1))
 
 NAME=OPENSSLTCP6_RANGE
 case "$TESTS" in
-*%$N%*|*%functions%*|*%security%*|*%tcp%*|*%tcp6%*|*%ip6%*|*%openssl%*|*%range%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%security%*|*%fork%*|*%tcp%*|*%tcp6%*|*%ip6%*|*%openssl%*|*%range%*|*%$NAME%*)
 TEST="$NAME: security of SSL-L over TCP/IPv6 with RANGE option"
 if ! eval $NUMCOND; then :;
 elif ! testfeats openssl >/dev/null; then
@@ -6399,7 +6400,7 @@ N=$((N+1))
 
 NAME=OPENSSLTCP6_SOURCEPORT
 case "$TESTS" in
-*%$N%*|*%functions%*|*%security%*|*%tcp%*|*%tcp6%*|*%ip6%*|*%openssl%*|*%sourceport%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%security%*|*%fork%*|*%tcp%*|*%tcp6%*|*%ip6%*|*%openssl%*|*%sourceport%*|*%$NAME%*)
 TEST="$NAME: security of SSL-L over TCP/IPv6 with SOURCEPORT option"
 if ! eval $NUMCOND; then :;
 elif ! testfeats openssl >/dev/null; then
@@ -6420,7 +6421,7 @@ N=$((N+1))
 
 NAME=OPENSSLTCP6_LOWPORT
 case "$TESTS" in
-*%$N%*|*%functions%*|*%security%*|*%tcp%*|*%tcp6%*|*%ip6%*|*%openssl%*|*%lowport%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%security%*|*%fork%*|*%tcp%*|*%tcp6%*|*%ip6%*|*%openssl%*|*%lowport%*|*%$NAME%*)
 TEST="$NAME: security of SSL-L over TCP/IPv6 with LOWPORT option"
 if ! eval $NUMCOND; then :;
 elif ! testfeats openssl >/dev/null; then
@@ -6441,7 +6442,7 @@ N=$((N+1))
 
 NAME=OPENSSLTCP6_TCPWRAP
 case "$TESTS" in
-*%$N%*|*%functions%*|*%security%*|*%tcp%*|*%tcp6%*|*%ip6%*|*%openssl%*|*%tcpwrap%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%security%*|*%fork%*|*%tcp%*|*%tcp6%*|*%ip6%*|*%openssl%*|*%tcpwrap%*|*%$NAME%*)
 TEST="$NAME: security of SSL-L over TCP/IPv6 with TCPWRAP option"
 if ! eval $NUMCOND; then :;
 elif ! feat=$(testfeats ip6 tcp libwrap openssl && runsip6); then
@@ -6464,7 +6465,7 @@ N=$((N+1))
 # test security with the openssl-commonname option on client side
 NAME=OPENSSL_CN_CLIENT_SECURITY
 case "$TESTS" in
-*%$N%*|*%functions%*|*%security%*|*%openssl%*|*%tcp%*|*%tcp4%*|*%ip4%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%security%*|*%fork%*|*%openssl%*|*%tcp%*|*%tcp4%*|*%ip4%*|*%$NAME%*)
 TEST="$NAME: security of client openssl-commonname option"
 # connect using non matching server name/address with commonname
 # options, this should succeed. Then without this option, should fail
@@ -6515,7 +6516,7 @@ N=$((N+1))
 
 NAME=OPENSSL_FIPS_SECURITY
 case "$TESTS" in
-*%$N%*|*%functions%*|*%security%*|*%openssl%*|*%fips%*|*%tcp%*|*%tcp4%*|*%ip4%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%security%*|*%fork%*|*%openssl%*|*%fips%*|*%tcp%*|*%tcp4%*|*%ip4%*|*%$NAME%*)
 TEST="$NAME: OpenSSL restrictions by FIPS"
 if ! eval $NUMCOND; then :;
 elif ! testfeats openssl >/dev/null; then
@@ -7108,7 +7109,12 @@ kill $pid0 2>/dev/null
 wait
 if ! diff "$tref" "$tf" >"$tdiff"; then
     $PRINTF "$FAILED\n"
-    cat "${te}0" "${te}1" "${te}2"
+    echo "$CMD0 &"
+    cat "${te}0" >&2
+    echo "$CMD1"
+    cat "${te}1" >&2
+    echo "$CMD2"
+    cat "${te}2" >&2
     cat "$tdiff"
     numFAIL=$((numFAIL+1))
     listFAIL="$listFAIL $N"
@@ -7908,7 +7914,7 @@ N=$((N+1))
 
 NAME=UDP4RECVFROM_RANGE
 case "$TESTS" in
-*%$N%*|*%functions%*|*%security%*|*%udp%*|*%udp4%*|*%ip4%*|*%range%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%security%*|*%fork%*|*%udp%*|*%udp4%*|*%ip4%*|*%range%*|*%$NAME%*)
 TEST="$NAME: security of UDP4-RECVFROM with RANGE option"
 newport udp4 	# provide free port number in $PORT
 #testserversec "$N" "$TEST" "$opts" "UDP4-RECVFROM:$PORT,reuseaddr,fork" "" "range=$SECONDADDR/32" "UDP4-SENDTO:127.0.0.1:$PORT" 4 udp $PORT 0
@@ -7920,7 +7926,7 @@ N=$((N+1))
 
 NAME=UDP4RECVFROM_TCPWRAP
 case "$TESTS" in
-*%$N%*|*%functions%*|*%security%*|*%udp%*|*%udp4%*|*%ip4%*|*%tcpwrap%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%security%*|*%fork%*|*%udp%*|*%udp4%*|*%ip4%*|*%tcpwrap%*|*%$NAME%*)
 TEST="$NAME: security of UDP4-RECVFROM with TCPWRAP option"
 if ! eval $NUMCOND; then :;
 elif ! feat=$(testfeats ip4 udp libwrap) || ! runsip4 >/dev/null; then
@@ -8056,7 +8062,7 @@ N=$((N+1))
 
 NAME=UDP6RECVFROM_RANGE
 case "$TESTS" in
-*%$N%*|*%functions%*|*%security%*|*%udp%*|*%udp6%*|*%ip6%*|*%range%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%security%*|*%fork%*|*%udp%*|*%udp6%*|*%ip6%*|*%range%*|*%$NAME%*)
 TEST="$NAME: security of UDP6-RECVFROM with RANGE option"
 if ! eval $NUMCOND; then :;
 elif ! feat=$(testfeats tcp ip6) || ! runsip6 >/dev/null; then
@@ -8176,7 +8182,7 @@ N=$((N+1))
 
 NAME=IP4RECVFROM_RANGE
 case "$TESTS" in
-*%$N%*|*%functions%*|*%security%*|*%ip%*|*%ip4%*|*%range%*|*%root%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%security%*|*%fork%*|*%ip%*|*%ip4%*|*%range%*|*%root%*|*%$NAME%*)
 TEST="$NAME: security of IP4-RECVFROM with RANGE option"
 if ! eval $NUMCOND; then :;
 elif ! feat=$(testfeats ip4 rawip) || ! runsip4 >/dev/null; then
@@ -8198,7 +8204,7 @@ N=$((N+1))
 
 NAME=IP4RECVFROM_TCPWRAP
 case "$TESTS" in
-*%$N%*|*%functions%*|*%security%*|*%ip%*|*%ip4%*|*%tcpwrap%*|*%root%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%security%*|*%fork%*|*%ip%*|*%ip4%*|*%tcpwrap%*|*%root%*|*%$NAME%*)
 TEST="$NAME: security of IP4-RECVFROM with TCPWRAP option"
 if ! eval $NUMCOND; then :;
 elif ! feat=$(testfeats ip4 rawip libwrap) || ! runsip4 >/dev/null; then
@@ -8281,7 +8287,7 @@ N=$((N+1))
 
 NAME=IP6RECVFROM_RANGE
 case "$TESTS" in
-*%$N%*|*%functions%*|*%security%*|*%ip%*|*%ip6%*|*%range%*|*%root%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%security%*|*%fork%*|*%ip%*|*%ip6%*|*%range%*|*%root%*|*%$NAME%*)
 TEST="$NAME: security of IP6-RECVFROM with RANGE option"
 if ! eval $NUMCOND; then :;
 elif ! feat=$(testfeats ip6 rawip && runsip6); then
@@ -8303,7 +8309,7 @@ N=$((N+1))
 
 NAME=IP6RECVFROM_TCPWRAP
 case "$TESTS" in
-*%$N%*|*%functions%*|*%security%*|*%ip%*|*%ip6%*|*%tcpwrap%*|*%root%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%security%*|*%fork%*|*%ip%*|*%ip6%*|*%tcpwrap%*|*%root%*|*%$NAME%*)
 TEST="$NAME: security of IP6-RECVFROM with TCPWRAP option"
 if ! eval $NUMCOND; then :;
 elif ! feat=$(testfeats ip6 rawip libwrap && runsip6); then
@@ -8650,49 +8656,70 @@ N=$((N+1))
 
 NAME=TCP4ENDCLOSE
 case "$TESTS" in
-*%$N%*|*%functions%*|*%ip4%*|*%ipapp%*|*%tcp%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%fork%*|*%ip4%*|*%ipapp%*|*%tcp%*|*%$NAME%*)
 TEST="$NAME: end-close keeps TCP V4 socket open"
 if ! eval $NUMCOND; then :; else
 tf="$td/test$N.stdout"
 te="$td/test$N.stderr"
 tdiff="$td/test$N.diff"
+newport tcp4; p0=$PORT
 newport tcp4; p1=$PORT
-newport tcp4; p2=$PORT
-da1a="$(date) $RANDOM"
-da1b="$(date) $RANDOM"
-CMD1="$TRACE $SOCAT $opts -u - TCP4-CONNECT:$LOCALHOST:$p1"
-CMD="$TRACE $SOCAT $opts -U TCP4:$LOCALHOST:$p2,end-close TCP4-LISTEN:$p1,bind=$LOCALHOST,$REUSEADDR,fork"
-CMD3="$TRACE $SOCAT $opts -u TCP4-LISTEN:$p2,$REUSEADDR,bind=$LOCALHOST -"
+da2a="$(date) $RANDOM"
+da2b="$(date) $RANDOM"
+CMD0="$TRACE $SOCAT -lp collector $opts -u TCP4-LISTEN:$p0,$REUSEADDR,bind=$LOCALHOST -"
+CMD1="$TRACE $SOCAT -lp forker $opts -U TCP4:$LOCALHOST:$p0,end-close TCP4-LISTEN:$p1,bind=$LOCALHOST,$REUSEADDR,fork"
+CMD2="$TRACE $SOCAT -lp client $opts -u - TCP4-CONNECT:$LOCALHOST:$p1"
 printf "test $F_n $TEST... " $N
-$CMD3 >"$tf" 2>"${te}3" &
-pid3=$!
-waittcp4port $p2 1
-$CMD 2>"${te}2" &
-pid2=$!
+$CMD0 >"${tf}0" 2>"${te}0" &
+pid0=$!
+waittcp4port $p0 1
+$CMD1 2>"${te}1" &
+pid1=$!
 usleep $MICROS
 waittcp4port $p1 1
-echo "$da1a" |$CMD1 2>>"${te}1a"
-echo "$da1b" |$CMD1 2>>"${te}1b"
+echo "$da2a" |$CMD2 2>>"${te}2a"
+rc2a=$?
+echo "$da2b" |$CMD2 2>>"${te}2b"
+rc2b=$?
 sleep 1
-kill "$pid3" "$pid2" 2>/dev/null
+kill "$pid0" "$pid1" 2>/dev/null
 wait
-if [ $? -ne 0 ]; then
-   $PRINTF "$FAILED: $TRACE $SOCAT:\n"
-   echo "$CMD1 &"
-   echo "$CMD2"
-   cat "${te}1a" "${te}1b" "${te}2" "${te}3"
+if [ $rc2a -ne 0 -o $rc2b -ne 0 ]; then
+    $PRINTF "$FAILED: $TRACE $SOCAT:\n"
+    echo "$CMD0 &"
+    cat "${te}0" >&2
+    echo "$CMD1"
+    cat "${te}1" >&2
+    echo "$CMD2"
+    cat "${te}2a" >&2
+    echo "$CMD2"
+    cat "${te}2b" >&2
     numFAIL=$((numFAIL+1))
     listFAIL="$listFAIL $N"
-elif ! $ECHO "$da1a\n$da1b" |diff - "$tf" >"$tdiff"; then
-   $PRINTF "$FAILED\n"
-   cat "$tdiff"
-   cat "${te}1a" "${te}1b" "${te}2" "${te}3"
+elif ! $ECHO "$da2a\n$da2b" |diff - "${tf}0" >"$tdiff"; then
+    $PRINTF "$FAILED (diff)\n"
+    echo "$CMD0 &"
+    cat "${te}0" >&2
+    echo "$CMD1"
+    cat "${te}1" >&2
+    echo "$CMD2"
+    cat "${te}2a" >&2
+    echo "$CMD2"
+    cat "${te}2b" >&2
+    cat "$tdiff"
     numFAIL=$((numFAIL+1))
     listFAIL="$listFAIL $N"
 else
-   $PRINTF "$OK\n"
-   if [ -n "$debug" ]; then cat "${te}1a" "${te}1b" "${te}2" "${te}3"; fi
-   numOK=$((numOK+1))
+    $PRINTF "$OK\n"
+    if [ "$VERBOSE" ]; then echo "$CMD0 &"; fi
+    if [ "$DEBUG" ];   then cat "${te}0" >&2; fi
+    if [ "$VERBOSE" ]; then echo "$CMD1 &"; fi
+    if [ "$DEBUG" ];   then cat "${te}1" >&2; fi
+    if [ "$VERBOSE" ]; then echo "$CMD2"; fi
+    if [ "$DEBUG" ];   then cat "${te}2a" >&2; fi
+    if [ "$VERBOSE" ]; then echo "$CMD2"; fi
+    if [ "$DEBUG" ];   then cat "${te}2b" >&2; fi
+    numOK=$((numOK+1))
 fi
 fi ;; # NUMCOND
 esac
@@ -8701,7 +8728,7 @@ N=$((N+1))
 
 NAME=EXECENDCLOSE
 case "$TESTS" in
-*%$N%*|*%functions%*|*%exec%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%fork%*|*%exec%*|*%$NAME%*)
 TEST="$NAME: end-close keeps EXEC child running"
 if ! eval $NUMCOND; then :; else
 tf="$td/test$N.stdout"
@@ -9875,7 +9902,7 @@ N=$((N+1))
 # process under some circumstances.
 NAME=EXECPTYKILL
 case "$TESTS" in
-*%$N%*|*%functions%*|*%bugs%*|*%exec%*|*%pty%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%bugs%*|*%fork%*|*%exec%*|*%pty%*|*%$NAME%*)
 TEST="$NAME: exec:...,pty explicitely kills sub process"
 # we want to check if the exec'd sub process is killed in time
 # for this we have a shell script that generates a file after two seconds;
@@ -10037,7 +10064,7 @@ N=$((N+1))
 # zombies because the master process did not catch SIGCHLD
 NAME=UDP4LISTEN_SIGCHLD
 case "$TESTS" in
-*%$N%*|*%functions%*|*%ip4%*|*%ipapp%*|*%udp%*|*%zombie%*|*%signal%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%fork%*|*%ip4%*|*%ipapp%*|*%udp%*|*%zombie%*|*%signal%*|*%$NAME%*)
 TEST="$NAME: test if UDP4-LISTEN child becomes zombie"
 # idea: run a udp-listen process with fork and -T. Connect once, so a sub
 # process is forked off. Make some transfer and wait until the -T timeout is
@@ -10091,7 +10118,7 @@ N=$((N+1))
 # zombies because the master process caught SIGCHLD but did not wait()
 NAME=UDP4RECVFROM_SIGCHLD
 case "$TESTS" in
-*%$N%*|*%functions%*|*%ip4%*|*%udp%*|*%dgram%*|*%zombie%*|*%signal%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%bugs%*|*%fork%*|*%ip4%*|*%udp%*|*%dgram%*|*%zombie%*|*%signal%*|*%$NAME%*)
 TEST="$NAME: test if UDP4-RECVFROM child becomes zombie"
 # idea: run a udp-recvfrom process with fork and -T. Send it one packet, so a
 # sub process is forked off. Make some transfer and wait until the -T timeout
@@ -10115,25 +10142,39 @@ rc2=$?
 sleep 1
 #read -p ">"
 l="$(childprocess $pid1)"
+#echo "l=\"$l\""
 kill $pid1 2>/dev/null; wait
 if [ $rc2 -ne 0 ]; then
     $PRINTF "$NO_RESULT\n"	# already handled in test UDP4DGRAM
+    if [ "$VERBOSE" ]; then echo "$CMD1 &"; fi
+    if [ "$DEBUG" ];   then cat "${te}1" >&2; fi
+    if [ "$VERBOSE" ]; then echo "$CMD2"; fi
+    if [ "$DEBUG" ];   then cat "${te}2" >&2; fi
     numCANT=$((numCANT+1))
     listCANT="$listCANT $N"
 elif ! echo "$da" |diff - "$tf" >"$tdiff"; then
     $PRINTF "$NO_RESULT\n"	# already handled in test UDP4DGRAM
+    if [ "$VERBOSE" ]; then echo "$CMD1 &"; fi
+    if [ "$DEBUG" ];   then cat "${te}1" >&2; fi
+    if [ "$VERBOSE" ]; then echo "$CMD2"; fi
+    if [ "$DEBUG" ];   then cat "${te}2" >&2; fi
     numCANT=$((numCANT+1))
     listCANT="$listCANT $N"
 elif $(isdefunct "$l"); then
     $PRINTF "$FAILED: $TRACE $SOCAT:\n"
     echo "$CMD1 &"
+    cat "${te}1" >&2
     echo "$CMD2"
+    cat "${te}2" >&2
     cat "${te}1" "${te}2"
     numFAIL=$((numFAIL+1))
     listFAIL="$listFAIL $N"
 else
     $PRINTF "$OK\n"
-    if [ -n "$debug" ]; then cat "${te}1" "${te}2"; fi
+    if [ "$VERBOSE" ]; then echo "$CMD1 &"; fi
+    if [ "$DEBUG" ];   then cat "${te}1" >&2; fi
+    if [ "$VERBOSE" ]; then echo "$CMD2"; fi
+    if [ "$DEBUG" ];   then cat "${te}2" >&2; fi
     numOK=$((numOK+1))
 fi
 fi ;; # NUMCOND
@@ -10204,7 +10245,7 @@ N=$((N+1))
 # child process.
 NAME=UDP4RECVFROM_FORK
 case "$TESTS" in
-*%$N%*|*%functions%*|*%ip4%*|*%udp%*|*%dgram%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%fork%*|*%ip4%*|*%udp%*|*%dgram%*|*%$NAME%*)
 TEST="$NAME: test if UDP4-RECVFROM handles more than one packet"
 # idea: run a UDP4-RECVFROM process with fork and -T. Send it one packet;
 # send it a second packet and check if this is processed properly. If yes, the
@@ -11293,7 +11334,7 @@ N=$((N+1))
 
 NAME=SOCKETRANGEMASK
 case "$TESTS" in
-*%$N%*|*%functions%*|*%security%*|*%generic%*|*%tcp%*|*%tcp4%*|*%ip4%*|*%socket%*|*%range%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%security%*|*%fork%*|*%generic%*|*%tcp%*|*%tcp4%*|*%ip4%*|*%socket%*|*%range%*|*%$NAME%*)
 TEST="$NAME: security of generic socket-listen with RANGE option"
 if ! eval $NUMCOND; then :;
 elif [ -z "$SECONDADDR" ]; then
@@ -11374,7 +11415,7 @@ N=$((N+1))
 # Test the generic setsockopt option
 NAME=SETSOCKOPT
 case "$TESTS" in
-*%$N%*|*%functions%*|*%ip4%*|*%tcp%*|*%generic%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%fork%*|*%ip4%*|*%tcp%*|*%generic%*|*%$NAME%*)
 TEST="$NAME: test the setsockopt option"
 # Set the TCP_MAXSEG (MSS) option with a reasonable value, this should succeed.
 # The try again with TCP_MAXSEG=1, this fails at least on Linux.
@@ -12096,7 +12137,7 @@ N=$((N+1))
 
 
 while read KEYW FEAT ADDR IPPORT; do
-if [ -z "$KEYW" ]|| [[ "$KEYW" == \#* ]]; then continue; fi
+if [ -z "$KEYW" ] || [[ "$KEYW" == \#* ]]; then continue; fi
 RUNS=$(tolower $KEYW)
 PROTO=$KEYW
 proto="$(echo "$PROTO" |tr A-Z a-z)"
@@ -12104,7 +12145,7 @@ feat="$(tolower "$FEAT")"
 # test the max-children option on really connection oriented sockets
 NAME=${KEYW}MAXCHILDREN
 case "$TESTS" in
-*%$N%*|*%functions%*|*%maxchildren%*|*%$feat%*|*%$proto%*|*%socket%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%fork%*|*%maxchildren%*|*%$feat%*|*%$proto%*|*%socket%*|*%$NAME%*)
 TEST="$NAME: max-children option"
 # start a listen process with max-children=1; connect with a client, let it
 # sleep some time before sending data; connect with second client that sends
@@ -12182,14 +12223,14 @@ UNIX  unix  $td/test\$N.server -
 
 
 while read KEYW FEAT ADDR IPPORT SHUT; do
-if [ -z "$KEYW" ]|| [[ "$KEYW" == \#* ]]; then continue; fi
+if [ -z "$KEYW" ] || [[ "$KEYW" == \#* ]]; then continue; fi
 RUNS=$(tolower $KEYW)
 PROTO=$KEYW
 proto="$(echo "$PROTO" |tr A-Z a-z)"
 # test the max-children option on pseudo connected sockets
 NAME=${KEYW}MAXCHILDREN
 case "$TESTS" in
-*%$N%*|*%functions%*|*%maxchildren%*|*%socket%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%fork%*|*%maxchildren%*|*%socket%*|*%$NAME%*)
 TEST="$NAME: max-children option"
 # start a listen process with max-children=1; connect with a client, let it
 # send data and then sleep; connect with second client that wants to send
@@ -12550,7 +12591,7 @@ N=$((N+1))
 # had a bug that converted a bit mask of 0 internally to 0xffffffff
 NAME=TCP4RANGE_0BITS
 case "$TESTS" in
-*%$N%*|*%functions%*|*%tcp%*|*%tcp4%*|*%ip4%*|*%range%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%fork%*|*%tcp%*|*%tcp4%*|*%ip4%*|*%range%*|*%$NAME%*)
 TEST="$NAME: correct evaluation of range mask 0"
 if ! eval $NUMCOND; then :;
 elif [ -z "$SECONDADDR" ]; then
@@ -12999,7 +13040,7 @@ if [ "$addropts" = "." ]; then addropts=; fi
 # $ADDR with fork removes the file system entry when the process is terminated
 NAME=${ADDR_}_REMOVE_FORK
 case "$TESTS" in
-*%$N%*|*%functions%*|*%bugs%*|*%unix%*|*%socket%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%bugs%*|*%fork%*|*%unix%*|*%socket%*|*%$NAME%*)
 TEST="$NAME: $ADDR with fork removes socket entry when terminated during accept"
 # start a socat process with listening unix domain socket etc and option fork.
 # Terminate the process and check if the file system socket entry still exists.
@@ -16069,6 +16110,101 @@ PORT=$((PORT+1))
 N=$((N+1))
 
 
+while read KEYW FEAT RUNS ADDR IPPORT; do
+if [ -z "$KEYW" ] || [[ "$KEYW" == \#* ]]; then continue; fi
+RUNS=$(tolower $KEYW)
+PROTO=$KEYW
+proto="$(echo "$PROTO" |tr A-Z a-z)"
+feat="$(tolower "$FEAT")"
+# test the fork option on really RECVFROM oriented sockets
+NAME=${KEYW}_FORK
+case "$TESTS" in
+*%$N%*|*%functions%*|*%fork%*|*%$feat%*|*%$proto%*|*%socket%*|*%$NAME%*)
+TEST="$NAME: ${KEYW}-RECVFROM with fork option"
+# Start a RECVFROM process with fork option and SYSTEM address where clients
+# data determines the sleep time; send a record with sleep before storing the
+# data, then send a record with 0 sleep before storing data.
+# When the second record is stored before the first one the test succeeded.
+if ! eval $NUMCOND; then :;
+elif ! F=$(testfeats $FEAT STDIO SYSTEM); then
+    $PRINTF "test $F_n $TEST... ${YELLOW}Feature $F not available${NORMAL}\n" $N
+    numCANT=$((numCANT+1))
+    listCANT="$listCANT $N"
+elif ! A=$(testaddrs - STDIO SYSTEM $PROTO-RECVFROM $PROTO-SENDTO); then
+    $PRINTF "test $F_n $TEST... ${YELLOW}Address $A not available${NORMAL}\n" $N
+    numCANT=$((numCANT+1))
+    listCANT="$listCANT $N"
+elif ! o=$(testoptions fork ) >/dev/null; then
+    $PRINTF "test $F_n $TEST... ${YELLOW}Option $o not available${NORMAL}\n" $N
+    numCANT=$((numCANT+1))
+    listCANT="$listCANT $N"
+elif ! runs$RUNS >/dev/null; then
+    $PRINTF "test $F_n $TEST... ${YELLOW}$(toupper $RUNS) not available${NORMAL}\n" $N
+    numCANT=$((numCANT+1))
+    listCANT="$listCANT $N"
+else
+case "X$IPPORT" in
+    "XPORT")
+    newport $proto
+    tsl=$PORT 		# test socket listen address
+    tsc="$ADDR:$PORT"	# test socket connect address
+    ;;
+    *)
+    tsl="$(eval echo "$ADDR")"	# resolve $N
+    tsc=$tsl
+esac
+#ts="$td/test$N.sock"
+tf="$td/test$N.stdout"
+te="$td/test$N.stderr"
+tdiff="$td/test$N.diff"
+da="test$N $(date) $RANDOM"
+CMD0="$TRACE $SOCAT $opts -t 3 $PROTO-RECVFROM:$tsl,fork SYSTEM:'read t x; sleep \$t; echo \$x >>'\"$tf\""
+CMD1="$TRACE $SOCAT $opts -t 3 - $PROTO-SENDTO:$tsc"
+printf "test $F_n $TEST... " $N
+eval $CMD0 </dev/null 2>"${te}0" &
+pid0=$!
+wait${proto}port $tsl 1
+echo "2 $da 1" |$CMD1 >"${tf}1" 2>"${te}1" &
+pid1=$!
+sleep 1
+echo "0 $da 2" |$CMD1 >"${tf}2" 2>"${te}2" &
+pid2=$!
+sleep 2
+cpids="$(childpids $pid0 </dev/null)"
+kill $pid1 $pid2 $cpids $pid0 2>/dev/null; wait
+if echo -e "$da 2\n$da 1" |diff - $tf >$tdiff; then
+    $PRINTF "$OK\n"
+    if [ "$VERBOSE" ]; then echo "$CMD0 &"; fi
+    if [ "$DEBUG" ];   then cat "${te}0" >&2; fi
+    if [ "$VERBOSE" ]; then echo "$CMD1"; fi
+    if [ "$DEBUG" ];   then cat "${te}1" >&2; fi
+    if [ "$VERBOSE" ]; then echo "$CMD2"; fi
+    if [ "$DEBUG" ];   then cat "${te}2" >&2; fi
+    numOK=$((numOK+1))
+else
+    $PRINTF "$FAILED\n"
+    echo "$CMD0 &"
+    cat "${te}0" >&2
+    echo "$CMD1"
+    cat "${te}1" >&2
+    echo "$CMD2"
+    cat "${te}2" >&2
+    echo "diff:" >&2
+    cat "$tdiff" >&2
+    numFAIL=$((numFAIL+1))
+    listFAIL="$listFAIL $N"
+    namesFAIL="$namesFAIL $NAME"
+fi
+fi # NUMCOND
+ ;;
+esac
+N=$((N+1))
+done <<<"
+UDP4  UDP  udp4  127.0.0.1 PORT
+UDP6  UDP  udp4  [::1]     PORT
+UNIX  unix unix   $td/test\$N.server -
+"
+
 # end of common tests
 
 ##################################################################################
diff --git a/xio-listen.c b/xio-listen.c
index 83a5f0b..54d69dc 100644
--- a/xio-listen.c
+++ b/xio-listen.c
@@ -338,11 +338,7 @@ int _xioopen_listen(struct single *xfd, int xioflags, struct sockaddr *us, sockl
 	 pid_t pid;	/* mostly int; only used with fork */
          sigset_t mask_sigchld;
 
-         /* we must prevent that the current packet triggers another fork;
-            therefore we wait for a signal from the recent child: USR1
-            indicates that is has consumed the last packet; CHLD means it has
-            terminated */
-         /* block SIGCHLD and SIGUSR1 until parent is ready to react */
+         /* Block SIGCHLD until parent is ready to react */
          sigemptyset(&mask_sigchld);
          sigaddset(&mask_sigchld, SIGCHLD);
          Sigprocmask(SIG_BLOCK, &mask_sigchld, NULL);
@@ -383,6 +379,7 @@ int _xioopen_listen(struct single *xfd, int xioflags, struct sockaddr *us, sockl
          /* now we are ready to handle signals */
          Sigprocmask(SIG_UNBLOCK, &mask_sigchld, NULL);
 
+
 	 while (maxchildren) {
 	    if (num_child < maxchildren) break;
 	    Notice("maxchildren are active, waiting");
diff --git a/xio-progcall.c b/xio-progcall.c
index c530983..50e314d 100644
--- a/xio-progcall.c
+++ b/xio-progcall.c
@@ -545,7 +545,7 @@ int _xioopen_foxec(int xioflags,	/* XIO_RDONLY etc. */
 	       applyopts(fdi, *copts, PH_LATE2);
 	    }
 	 if (withfork) {
-	    Info("Signalling parent ready");
+	    Info("notifying parent that child process is ready");
 	    Close(trigger[1]); 	/* in child, notify parent that ready */
 	 }
       } /* withfork */
@@ -603,7 +603,7 @@ int _xioopen_foxec(int xioflags,	/* XIO_RDONLY etc. */
       fds[0].fd = trigger[0];
       fds[0].events = POLLIN|POLLHUP;
       Poll(fds, 1, -1);
-      Info("Child process signalled ready");
+      Info("child process notified parent that it is ready");
    }
 
    return pid;	/* indicate parent (main) process */
diff --git a/xio-socket.c b/xio-socket.c
index 78ff176..f1d8410 100644
--- a/xio-socket.c
+++ b/xio-socket.c
@@ -1084,101 +1084,13 @@ int _xioopen_dgram_sendto(/* them is already in xfd->peersa */
    packet in the IP stacks input queue and forks a sub process. The sub process
    then reads this packet for processing its data.
    There is a problem because the parent process would find the same packet
-   again if it calls select()/poll() before the child process reads the
+   again if it calls select()/poll() before the child process has read the
    packet.
    To solve this problem we implement the following mechanism:
-   The sub process sends a SIGUSR1 when it has read the packet (or a SIGCHLD if
-   it dies before). The parent process waits until it receives that signal and
-   only then continues to listen.
-   To prevent a signal from another process to trigger our loop, we pass the
-   pid of the sub process to the signal handler in xio_waitingfor. The signal
-   handler sets xio_hashappened if the pid matched.
+   Before forking an unnamed pipe (fifo) is created. The sub process closes the
+   write side when it has read the packet. The parent process waits until the
+   read side of the pipe gives EOF and only then continues to listen.
 */
-static pid_t xio_waitingfor;	/* info from recv loop to signal handler:
-				   indicates the pid of the child process
-				   that should send us the USR1 signal */
-static bool xio_hashappened;	/* info from signal handler to loop: child
-				   process has read ("consumed") the packet */
-static int xio_childstatus;
-
-/* this is the signal handler for USR1 and CHLD */
-void xiosigaction_hasread(int signum
-#if HAVE_STRUCT_SIGACTION_SA_SIGACTION && defined(SA_SIGINFO)
-			  , siginfo_t *siginfo, void *ucontext
-#endif
-			  ) {
-   pid_t pid;
-   int _errno;
-   int status = 0;
-   bool wassig = false;
-
-   _errno = errno;
-   diag_in_handler = 1;
-#if HAVE_STRUCT_SIGACTION_SA_SIGACTION && defined(SA_SIGINFO)
-   Debug5("xiosigaction_hasread(%d, {%d,%d,%d,"F_pid"}, )",
-	  signum, siginfo->si_signo, siginfo->si_errno, siginfo->si_code,
-	  siginfo->si_pid);
-#else
-   Debug1("xiosigaction_hasread(%d)", signum);
-#endif
-   if (signum == SIGCHLD) {
-      do {
-	 pid = Waitpid(-1, &status, WNOHANG);
-	 if (pid == 0) {
-	    Msg(wassig?E_INFO:E_WARN,
-		"waitpid(-1, {}, WNOHANG): no child has exited");
-	    Info("xiosigaction_hasread() finished");
-	    Debug("xiosigaction_hasread() ->");
-	    diag_in_handler = 0;
-	    errno = _errno;
-	    return;
-	 } else if (pid < 0 && errno == EINTR) {
-	    Info1("xiosigaction_hasread(): %s", strerror(errno));
-	 } else if (pid < 0 && errno == ECHILD) {
-	    Msg(wassig?E_INFO:E_NOTICE,
-		 "waitpid(-1, {}, WNOHANG): "F_strerror);
-	    Info("xiosigaction_hasread() finished");
-	    Debug("xiosigaction_hasread() ->");
-	    diag_in_handler = 0;
-	    errno = _errno;
-	    return;
-	 }
-	 wassig = true;
-	 if (pid < 0) {
-	    Warn1("waitpid(-1, {%d}, WNOHANG): "F_strerror, status);
-	    Info("xiosigaction_hasread() finished");
-	    Debug("xiosigaction_hasread() ->");
-	    diag_in_handler = 0;
-	    errno = _errno;
-	    return;
-	 }
-	 if (pid == xio_waitingfor) {
-	    xio_waitingfor = 0; 	/* so this child will not set hashappened again */
-	    xio_hashappened = true;
-            xio_childstatus = WEXITSTATUS(status);
-	    Debug("xiosigaction_hasread() ->");
-	    diag_in_handler = 0;
-	    errno = _errno;
-	    return;
-	 }
-      } while (1);
-   }
-#if HAVE_STRUCT_SIGACTION_SA_SIGACTION && defined(SA_SIGINFO)
-   if (xio_waitingfor == siginfo->si_pid) {
-      xio_hashappened = true;
-   }
-#else
-   xio_hashappened = true;
-#endif
-#if !HAVE_SIGACTION
-   Signal(sig, xiosigaction_hasread);
-#endif /* !HAVE_SIGACTION */
-   Debug("xiosigaction_hasread() ->");
-   diag_in_handler = 0;
-   errno = _errno;
-   return;
-}
-
 
 /* waits for incoming packet, checks its source address and port. Depending
    on fork option, it may fork a subprocess.
@@ -1267,42 +1179,7 @@ int _xioopen_dgram_recvfrom(struct single *xfd, int xioflags,
    }
 
    if (dofork) {
-#if HAVE_SIGACTION
-   {
-      struct sigaction act;
-      memset(&act, 0, sizeof(struct sigaction));
-      act.sa_flags   = SA_NOCLDSTOP/*|SA_RESTART*/
-#ifdef SA_SIGINFO /* not on Linux 2.0(.33) */
-	 |SA_SIGINFO
-#endif
-#ifdef SA_NOMASK
-         |SA_NOMASK
-#endif
-         ;
-#if HAVE_STRUCT_SIGACTION_SA_SIGACTION && defined(SA_SIGINFO)
-      act.sa_sigaction = xiosigaction_hasread;
-#else /* Linux 2.0(.33) does not have sigaction.sa_sigaction */
-      act.sa_handler = xiosigaction_hasread;
-#endif
-      sigfillset(&act.sa_mask);
-      if (Sigaction(SIGUSR1, &act, NULL) < 0) {
-         /*! Linux man does not explicitely say that errno is defined */
-         Warn1("sigaction(SIGUSR1, {&xiosigaction_subaddr_ok}, NULL): %s", strerror(errno));
-      }
-      if (Sigaction(SIGCHLD, &act, NULL) < 0) {
-         /*! Linux man does not explicitely say that errno is defined */
-         Warn1("sigaction(SIGCHLD, {&xiosigaction_subaddr_ok}, NULL): %s", strerror(errno));
-      }
-   }
-#else /* !HAVE_SIGACTION */
-   /*!!!*/
-      if (Signal(SIGUSR1, xiosigaction_hasread) == SIG_ERR) {
-	 Warn1("signal(SIGUSR1, xiosigaction_hasread): %s", strerror(errno));
-      }
-      if (Signal(SIGCHLD, xiosigaction_hasread) == SIG_ERR) {
-	 Warn1("signal(SIGCHLD, xiosigaction_hasread): %s", strerror(errno));
-      }
-#endif /* !HAVE_SIGACTION */
+      xiosetchilddied();
    }
 
    while (true) {	/* but we only loop if fork option is set */
@@ -1314,6 +1191,7 @@ int _xioopen_dgram_recvfrom(struct single *xfd, int xioflags,
       socklen_t palen = sizeof(_peername);	/* peer address size */
       char ctrlbuff[1024];			/* ancillary messages */
       struct msghdr msgh = {0};
+      int trigger[2]; 	/* for socketpair that indicates consumption of packet */
       int rc;
 
       socket_init(pf, pa);
@@ -1397,29 +1275,22 @@ int _xioopen_dgram_recvfrom(struct single *xfd, int xioflags,
       xfd->salen = palen;
 
       if (dofork) {
-	 sigset_t oldset, mask_sigchldusr1;
-
-	 /* we must prevent that the current packet triggers another fork;
-	    therefore we wait for a signal from the recent child: USR1
-	    indicates that is has consumed the last packet; CHLD means it has
-	    terminated */
-	 /* block SIGCHLD and SIGUSR1 until parent is ready to react */
-	 Sigprocmask(SIG_BLOCK, NULL, &mask_sigchldusr1);
-	 sigaddset(&mask_sigchldusr1, SIGCHLD);
-	 sigaddset(&mask_sigchldusr1, SIGUSR1);
-	 Sigprocmask(SIG_SETMASK, &mask_sigchldusr1, &oldset);
+	 Info("Generating socketpair that triggers parent when packet has been consumed");
+	 if (Socketpair(PF_UNIX, SOCK_STREAM, 0, trigger) < 0) {
+	    Error1("socketpair(PF_UNIX, SOCK_STREAM, 0, ...): %s", strerror(errno));
+	 }
 
 	 if ((pid = xio_fork(false, level)) < 0) {
+	    Close(trigger[0]);
+	    Close(trigger[1]);
 	    Close(xfd->fd);
-	    Sigprocmask(SIG_SETMASK, &oldset, NULL);
 	    return STAT_RETRYLATER;
 	 }
 
 	 if (pid == 0) {	/* child */
-	    /* no reason to block SIGCHLD in child process */
-	    Sigprocmask(SIG_SETMASK, &oldset, NULL);
-	    xfd->ppid = Getppid();	/* send parent a signal when packet has
-					   been consumed */
+	    Close(trigger[0]);
+	    xfd->triggerfd = trigger[1];
+	    Fcntl_l(xfd->triggerfd, F_SETFD, FD_CLOEXEC);
 
 #if WITH_RETRY
 	    /* !? */
@@ -1437,29 +1308,14 @@ int _xioopen_dgram_recvfrom(struct single *xfd, int xioflags,
 	    break;
 	 }
 
-	 xio_waitingfor = pid;
+	 /* Parent */
+	 Close(trigger[1]);
 
-	 do {
-#if HAVE_PSELECT
-	  {
-	    struct timespec timeout = { LONG_MAX, 0 };
-	    Pselect(0, NULL, NULL, NULL, &timeout, &oldset);
-	    Sigprocmask(SIG_SETMASK, &oldset, NULL);
-	  }
-#else /* ! HAVE_PSELECT */
-	  /* now we are ready to handle signals */
-	  Sigprocmask(SIG_SETMASK, &oldset, NULL);
-	  Sleep(1);	/* any signal speeds up return */
-#endif /* ! HAVE_PSELECT */
-	 } while (!xio_hashappened) ;
-	 xio_hashappened = false;
+	 {
+	    char buf[1];
+	    while (Read(trigger[0], buf, 1) < 0 && errno == EINTR) ;
+	 }
 
-         if (xio_childstatus != 0) {
-             char buff[512];
-             Recv(xfd->fd, buff, sizeof(buff), 0);
-             xio_childstatus = 0;
-             Info("drop data because of child exit failed");
-         }
 	 Info("continue listening");
       } else {
 	break;
diff --git a/xio-udp.c b/xio-udp.c
index 4359510..074f4f9 100644
--- a/xio-udp.c
+++ b/xio-udp.c
@@ -226,7 +226,9 @@ int _xioopen_ipdgram_listen(struct single *sfd,
 	 }
 
 	 /* server: continue loop with socket()+recvfrom() */
-	 /* when we dont close this we get awkward behaviour on Linux 2.4:
+	 /* This avoids the requirement of a sync (trigger) mechanism as with
+	    RECVFROM addresses */
+	 /* And when we dont close this we got awkward behaviour on Linux 2.4:
 	    recvfrom gives 0 bytes with invalid socket address */
 	 if (Close(sfd->fd) < 0) {
 	    Info2("close(%d): %s", sfd->fd, strerror(errno));
diff --git a/xio.h b/xio.h
index 92035e6..286cee4 100644
--- a/xio.h
+++ b/xio.h
@@ -164,6 +164,7 @@ typedef struct single {
    size_t actbytes;	/* so many bytes still to be read (when readbytes!=0)*/
    xiolock_t lock;	/* parameters of lockfile */
    bool      havelock;	/* we are happy owner of the above lock */
+   int 		triggerfd; 	/* close this FD in child process to signal parent */
    bool	     cool_write;	/* downlevel EPIPE, ECONNRESET to notice */
    /* until here, keep consistent with bipipe.dual ! */
    int argc;		/* number of fields in argv */
@@ -199,7 +200,6 @@ typedef struct single {
    struct termios savetty;	/* save orig tty settings for later restore */
 #endif /* WITH_TERMIOS */
    int (*sigchild)(struct single *);	/* callback after sigchild */
-   pid_t ppid;			/* parent pid, only if we send it signals */
    int escape;			/* escape character; -1 for no escape */
    bool actescape;		/* escape character found in input data */
    union {
@@ -312,7 +312,9 @@ typedef union bipipe {
       size_t actbytes;	/* so many bytes still to be read */
       xiolock_t lock;	/* parameters of lockfile */
       bool      havelock;	/* we are happy owner of the above lock */
-      xiosingle_t *stream[2];	/* input stream, output stream */
+      int 	triggerfd; 	/* close this FD in child process to notify parent */
+      bool      cool_write;	/* downlevel EPIPE, ECONNRESET to notice */
+      struct single *stream[2];	/* input stream, output stream */
    } dual;
 } xiofile_t;
 
diff --git a/xioinitialize.c b/xioinitialize.c
index 81925e9..4118ab6 100644
--- a/xioinitialize.c
+++ b/xioinitialize.c
@@ -217,6 +217,15 @@ pid_t xio_fork(bool subchild, int level) {
       if (!subchild) {
 	 /* set SOCAT_PID to new value */
 	 xiosetenvulong("PID", pid, 1);
+      } else {
+	 /* Make sure the sub process does not hold the trigger pipe open */
+	 if (sock1 != NULL) {
+	    struct single *sfd;
+	    sfd = XIO_RDSTREAM(sock1);
+	    if (sfd->triggerfd >= 0)  Close(sfd->triggerfd);
+	    sfd = XIO_WRSTREAM(sock1);
+	    if (sfd->triggerfd >= 0)  Close(sfd->triggerfd);
+	 }
       }
       /* gdb recommends to have env controlled sleep after fork */
       if (forkwaitstring = getenv("SOCAT_FORK_WAIT")) {
diff --git a/xioopen.c b/xioopen.c
index f879365..b93999b 100644
--- a/xioopen.c
+++ b/xioopen.c
@@ -363,7 +363,7 @@ static xiofile_t *xioallocfd(void) {
 #endif /* WITH_RETRY */
 /* fd->common.ignoreeof = false; */
 /* fd->common.eof       = 0; */
-
+   fd->stream.triggerfd = -1;
    fd->stream.fd        = -1;
    fd->stream.dtype     = XIODATA_STREAM;
 #if _WITH_SOCKET
diff --git a/xioread.c b/xioread.c
index b05db3f..9df0ee2 100644
--- a/xioread.c
+++ b/xioread.c
@@ -271,8 +271,10 @@ ssize_t xioread(xiofile_t *file, void *buff, size_t bufsiz) {
 #else
 	 Shutdown(pipe->fd, SHUT_RD);
 #endif
-	 if (pipe->ppid > 0) {
-	    Kill(pipe->ppid, SIGUSR1);
+	 if (pipe->triggerfd >= 0) {
+	    Info("notifying parent that socket is ready again");
+	    Close(pipe->triggerfd);
+	    pipe->triggerfd = -1;
 	 }
       }
 
diff --git a/xiosigchld.c b/xiosigchld.c
index 98abb70..81f5dbc 100644
--- a/xiosigchld.c
+++ b/xiosigchld.c
@@ -112,7 +112,6 @@ void childdied(int signum) {
 	 return;
       }
    /*! indent */
-   if (num_child) num_child--;
    /* check if it was a registered child process */
    i = 0;
    while (i < XIO_MAXSOCK) {
@@ -121,6 +120,7 @@ void childdied(int signum) {
    }
    if (i == XIO_MAXSOCK) {
 	 Info2("childdied(%d): cannot identify child %d", signum, pid);
+	 if (num_child) num_child--;
 	 if (nextunknown == NUMUNKNOWN) {
 	    nextunknown = 0;
 	 }