diff --git a/CHANGES b/CHANGES
index 4c3d9a3..83d59e4 100644
--- a/CHANGES
+++ b/CHANGES
@@ -17,6 +17,7 @@
   introduce io_eagain_read and io_eagain_write (discontinue using io_eagain plz)
   fix buffer_get
   add fmt_html_tagarg, fmt_xml, scan_html_tagarg
+  add socket_fastopen, socket_fastopen_connect4, socket_fastopen_connect6 and socket_quickack
 
 0.29:
   save 8 bytes in taia.h for 64-bit systems
diff --git a/socket.h b/socket.h
index 279545a..2ece1fd 100644
--- a/socket.h
+++ b/socket.h
@@ -39,7 +39,9 @@ int socket_accept6(int s,char* ip,uint16* port,uint32* scope_id);
 ssize_t socket_recv4(int s,char* buf,size_t len,char* ip,uint16* port);
 ssize_t socket_recv6(int s,char* buf,size_t len,char* ip,uint16* port,uint32* scope_id);
 ssize_t socket_send4(int s,const char* buf,size_t len,const char* ip,uint16 port);
+ssize_t socket_send4_flag(int s,const char* buf,size_t len,const char* ip,uint16 port,int flags);
 ssize_t socket_send6(int s,const char* buf,size_t len,const char* ip,uint16 port,uint32 scope_id);
+ssize_t socket_send6_flag(int s,const char* buf,size_t len,const char* ip,uint16 port,uint32 scope_id,int flags);
 int socket_local4(int s,char* ip,uint16* port);
 int socket_local6(int s,char* ip,uint16* port,uint32* scope_id);
 int socket_remote4(int s,char* ip,uint16* port);
@@ -60,7 +62,7 @@ int socket_mchopcount6(int s,char hops);
 int socket_mcloop4(int s,char loop);
 int socket_mcloop6(int s,char loop);
 
-/* please note that these are platform specific.  Do not expect them to
+/* Please note that these are platform specific.  Do not expect them to
  * work.  You might still get an accept() signalled even though there is
  * no data available.  So far, DATAIN is supported on FreeBSD and Linux,
  * and HTTPIN is supported on FreeBSD. */
@@ -78,6 +80,24 @@ uint32 socket_getifidx(const char* ifname);
 
 extern int noipv6;
 
+
+/* if HAVE_SOCKET_FASTOPEN is #defined, your version of libowfat
+ * has socket_fastopen, socket_fastopen_connect4,
+ * socket_fastopen_connect6 and socket_quickack */
+#define HAVE_SOCKET_FASTOPEN
+
+/* Turn on server-side TCP fast open support (0 success, -1 error) */
+int socket_fastopen(int s);
+
+/* Turn quick ack mode on or off for the socket s. */
+int socket_quickack(int s,int value);
+
+/* For client-side TCP fast open, connect and sending the first data is
+ * just one step, so we need an API to do it in one step */
+ssize_t socket_fastopen_connect4(int s,const char* ip,uint16 port,const char* buf,size_t len);
+ssize_t socket_fastopen_connect6(int s,const char* ip,uint16 port,uint32 scope_id,const char* buf,size_t len);
+
+
 #ifdef __MINGW32__
 #include <winsock2.h>
 #include <ws2tcpip.h>
diff --git a/socket/socket_connect4.3 b/socket/socket_connect4.3
index 2d6a60b..64fb2f1 100644
--- a/socket/socket_connect4.3
+++ b/socket/socket_connect4.3
@@ -45,4 +45,4 @@ effect as first calling socket_bind4 with IP address 0.0.0.0 and port 0.
   socket_connect4(s,ip,p);
 
 .SH "SEE ALSO"
-socket_connect6(3)
+socket_connect6(3), socket_fastopen_connect4(3)
diff --git a/socket/socket_connect6.3 b/socket/socket_connect6.3
index 76a2f20..b534d56 100644
--- a/socket/socket_connect6.3
+++ b/socket/socket_connect6.3
@@ -51,4 +51,4 @@ effect as first calling socket_bind6 with IP address :: and port 0.
   socket_connect6(s,ip,p,0);
 
 .SH "SEE ALSO"
-socket_connect4(3), socket_getifname(3)
+socket_connect4(3), socket_fastopen_connect6(3), socket_getifname(3)
diff --git a/socket/socket_fastopen.3 b/socket/socket_fastopen.3
new file mode 100644
index 0000000..1dea660
--- /dev/null
+++ b/socket/socket_fastopen.3
@@ -0,0 +1,30 @@
+.TH socket_fastopen 3
+.SH NAME
+socket_fastopen \- enable TCP Fast Open on a server-side TCP socket
+.SH SYNTAX
+.B #include <socket.h>
+
+int \fBsocket_fastopen\fP(int \fIs\fR);
+.SH DESCRIPTION
+socket_fastopen enables TCP Fast Open support on a server-side TCP
+socket.  Call this before socket_listen().  If the platform does not
+support this functionality, returns -1 and sets errno to ENOPROTOOPT (or
+ENOSYS if the platform does not define ENOPROTOOPT).
+
+Normally socket_fastopen returns 0. If anything goes wrong, socket_fastopen
+returns -1, setting errno appropriately.
+
+.SH EXAMPLE
+  #include <socket.h>
+
+  int \fIs\fR;
+  char \fIip\fR[4];
+  uint16 \fIp\fR;
+
+  \fIs\fR = socket_tcp4b();
+  socket_fastopen(s);
+  socket_bind4_reuse(s,ip,p);
+  socket_listen(16);
+
+.SH "SEE ALSO"
+socket_fastopen_connect4(3), socket_fastopen_connect6(3)
diff --git a/socket/socket_fastopen_connect4.3 b/socket/socket_fastopen_connect4.3
new file mode 100644
index 0000000..f5b8ecb
--- /dev/null
+++ b/socket/socket_fastopen_connect4.3
@@ -0,0 +1,58 @@
+.TH socket_fastopen_connect4 3
+.SH NAME
+socket_fastopen_connect4 \- make a TCP connection and send some data
+.SH SYNTAX
+.B #include <socket.h>
+
+ssize_t \fBsocket_fastopen_connect4\fP(int \fIs\fR,const char \fIip\fR[4],uint16 \fIport\fR,
+                                 const char* \fIbuf\fR,size_t \fIlen\fR);
+.SH DESCRIPTION
+socket_fastopen_connect4 attempts to make a connection from TCP socket \fIs\fR to
+TCP port \fIport\fR on IP address \fIip\fR.  If that succeeds, it
+attempts to send \fIlen\fR bytes from \fIbuf\fR.
+
+The difference to calling socket_connect4 followed by write is that, on
+platforms supporting TCP Fast Open, socket_fastopen_connect4 will send
+the first data packet in the third packet of the TCP handshake, saving
+one useless ACK packet in network traffic.
+
+This is only useful for protocols where the client sends the first
+bytes.
+
+socket_connect4 may return
+.sp 1
+.IP \(bu
+>=0, to indicate that the connection succeeded and this many bytes were
+sent.
+.IP \(bu
+-1, setting errno to error_inprogress or error_wouldblock, to indicate
+that the socket is non-blocking
+.IP \(bu
+-1, setting errno to something else, to indicate that the connection
+failed (and failed immediately, if the socket is non-blocking).
+.PP
+
+When a background connection succeeds or fails, \fIs\fR becomes
+writable; you can use socket_connected to see whether the connection
+succeeded.  If the connection failed, socket_connected returns 0,
+setting errno appropriately.
+
+Once a TCP socket is connected, you can use the read and write
+system calls to transmit data.
+
+You can call socket_connect4 without calling socket_bind4.  This has the
+effect as first calling socket_bind4 with IP address 0.0.0.0 and port 0.
+
+.SH EXAMPLE
+  #include <socket.h>
+
+  int \fIs\fR;
+  char \fIip\fR[4];
+  uint16 \fIp\fR;
+
+  \fIs\fR = socket_tcp4();
+  socket_bind4(s,ip,p);
+  socket_fastopen_connect4(s,ip,p,"hello",5);
+
+.SH "SEE ALSO"
+socket_connect4(3), socket_fastopen_connect6(3), socket_fastopen(3)
diff --git a/socket/socket_fastopen_connect6.3 b/socket/socket_fastopen_connect6.3
new file mode 100644
index 0000000..e4b6b9d
--- /dev/null
+++ b/socket/socket_fastopen_connect6.3
@@ -0,0 +1,60 @@
+.TH socket_fastopen_connect6 3
+.SH NAME
+socket_fastopen_connect6 \- make a TCP connection and send some data
+.SH SYNTAX
+.B #include <socket.h>
+
+ssize_t \fBsocket_fastopen_connect6\fP(int \fIs\fR,
+                 const char \fIip\fR[16],uint16 \fIport\fR,uint32 \fIscope_id\fR,
+                 const char* \fIbuf\fR,size_t \fIlen\fR);
+.SH DESCRIPTION
+socket_fastopen_connect6 attempts to make a connection from TCP socket \fIs\fR to
+TCP port \fIport\fR on IP address \fIip\fR.  If that succeeds, it
+attempts to send \fIlen\fR bytes from \fIbuf\fR.
+
+The difference to calling socket_connect6 followed by write is that, on
+platforms supporting TCP Fast Open, socket_fastopen_connect6 will send
+the first data packet in the third packet of the TCP handshake, saving
+one useless ACK packet in network traffic.
+
+This is only useful for protocols where the client sends the first
+bytes.
+
+socket_connect6 may return
+.sp 1
+.IP \(bu
+>=0, to indicate that the connection succeeded and this many bytes were
+sent.
+.IP \(bu
+-1, setting errno to error_inprogress or error_wouldblock, to indicate
+that the socket is non-blocking
+.IP \(bu
+-1, setting errno to something else, to indicate that the connection
+failed (and failed immediately, if the socket is non-blocking).
+.PP
+
+When a background connection succeeds or fails, \fIs\fR becomes
+writable; you can use socket_connected to see whether the connection
+succeeded.  If the connection failed, socket_connected returns 0,
+setting errno appropriately.
+
+Once a TCP socket is connected, you can use the read and write
+system calls to transmit data.
+
+You can call socket_connect6 without calling socket_bind6.  This has the
+effect as first calling socket_bind6 with IP address :: and port 0.
+
+.SH EXAMPLE
+  #include <socket.h>
+
+  int \fIs\fR;
+  char \fIip\fR[16];
+  uint16 \fIp\fR;
+  uint32 \fIscope_id\fR;
+
+  \fIs\fR = socket_tcp6b();
+  socket_bind6(s,ip,p);
+  socket_fastopen_connect6(s,ip,p,scope_id,"hello",5);
+
+.SH "SEE ALSO"
+socket_connect6(3), socket_fastopen_connect4(3), socket_fastopen(3)
diff --git a/socket/socket_quickack.3 b/socket/socket_quickack.3
new file mode 100644
index 0000000..620f954
--- /dev/null
+++ b/socket/socket_quickack.3
@@ -0,0 +1,38 @@
+.TH socket_quickack 3
+.SH NAME
+socket_quickack \- turn TCP Quick ACK mode on or off
+.SH SYNTAX
+.B #include <socket.h>
+
+int \fBsocket_quickack\fP(int \fIs\fR,int \fIvalue\fR);
+.SH DESCRIPTION
+socket_quickack switches TCP Quick ACK mode on (value=1) or off
+(value=0).  If the platform does not support this functionality, returns
+-1 and sets errno to ENOPROTOOPT (or ENOSYS if the platform does not
+define ENOPROTOOPT).
+
+TCP Quick ACK mode is on by default because the operating system has to
+assume it's an interactive connection.  In that case, an ACK will be
+sent quickly after data came in.  If your code handles non-interactive
+server connections, it may make sense to switch Quick ACK mode off,
+telling the kernel to delay sending ACKs because the server is going to
+respond to incoming requests anyway, so the ACK can be piggy-backed onto
+that response, saving useless network traffic.
+
+Normally socket_quickack returns 0. If anything goes wrong, socket_quickack
+returns -1, setting errno appropriately.
+
+.SH EXAMPLE
+  #include <socket.h>
+
+  int \fIs\fR;
+  char \fIip\fR[4];
+  uint16 \fIp\fR;
+
+  \fIs\fR = socket_tcp4b();
+  socket_quickack(s);
+  socket_bind4_reuse(s,ip,p);
+  socket_listen(16);
+
+.SH "SEE ALSO"
+socket_fastopen(3)
diff --git a/socket/socket_quickack.c b/socket/socket_quickack.c
new file mode 100644
index 0000000..cd027f8
--- /dev/null
+++ b/socket/socket_quickack.c
@@ -0,0 +1,18 @@
+#include "socket.h"
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/tcp.h>
+#include <errno.h>
+
+int socket_quickack(int s,int value) {
+#ifdef TCP_QUICKACK
+  return setsockopt(s, SOL_TCP, TCP_QUICKACK, &value, sizeof(int));
+#else
+#ifdef ENOPROTOOPT
+  errno=ENOPROTOOPT;
+#else
+  errno=ENOSYS;
+#endif
+  return -1;
+#endif
+}
diff --git a/socket/socket_send4.3 b/socket/socket_send4.3
index 13cc779..685be73 100644
--- a/socket/socket_send4.3
+++ b/socket/socket_send4.3
@@ -5,7 +5,7 @@ socket_send4 \- send a UDP datagram
 .B #include <socket.h>
 
 ssize_t \fBsocket_send4\fP(int \fIs\fR, const char* \fIbuf\fR, size_t \fIlen\fR,
-                 const char \fIip\fR[4],uint16 \fIport\fR);
+                     const char \fIip\fR[4],uint16 \fIport\fR);
 .SH DESCRIPTION
 socket_send4 sends \fIlen\fR bytes starting at \fIbuf\fR in a UDP
 datagram over the socket \fIs\fR to UDP port \fIport\fR on IP address
diff --git a/socket/socket_send4.c b/socket/socket_send4.c
index c2ace8b..3255f3d 100644
--- a/socket/socket_send4.c
+++ b/socket/socket_send4.c
@@ -8,12 +8,16 @@
 #include "byte.h"
 #include "socket.h"
 
-ssize_t socket_send4(int s,const char *buf,size_t len,const char ip[4],uint16 port) {
+ssize_t socket_send4_flag(int s,const char *buf,size_t len,const char ip[4],uint16 port,int flag) {
   struct sockaddr_in si;
 
   byte_zero(&si,sizeof si);
   si.sin_family = AF_INET;
   uint16_pack_big((char*) &si.sin_port,port);
   *((uint32*)&si.sin_addr) = *((uint32*)ip);
-  return winsock2errno(sendto(s,buf,len,0,(void*) &si,sizeof si));
+  return winsock2errno(sendto(s,buf,len,flag,(void*) &si,sizeof si));
+}
+
+ssize_t socket_send4(int s,const char *buf,size_t len,const char ip[4],uint16 port) {
+  return socket_send4_flag(s,buf,len,ip,port,0);
 }
diff --git a/socket/socket_send6.3 b/socket/socket_send6.3
index 9fddb57..1fa6a24 100644
--- a/socket/socket_send6.3
+++ b/socket/socket_send6.3
@@ -5,7 +5,7 @@ socket_send6 \- send a UDP datagram
 .B #include <socket.h>
 
 ssize_t \fBsocket_send6\fP(int \fIs\fR, const char* \fIbuf\fR, size_t \fIlen\fR,
-         const char \fIip\fR[16], uint16 \fIport\fR, uint32 \fIscope_id\fR);
+                     const char \fIip\fR[16], uint16 \fIport\fR, uint32 \fIscope_id\fR);
 .SH DESCRIPTION
 socket_send6 sends \fIlen\fR bytes starting at \fIbuf\fR in a UDP
 datagram over the socket \fIs\fR to UDP port \fIport\fR on IP address
diff --git a/socket/socket_send6.c b/socket/socket_send6.c
index f30bbc5..21ee14e 100644
--- a/socket/socket_send6.c
+++ b/socket/socket_send6.c
@@ -13,7 +13,7 @@
 #include "ip4.h"
 #include "havescope.h"
 
-ssize_t socket_send6(int s,const char *buf,size_t len,const char ip[16],uint16 port,uint32 scope_id)
+ssize_t socket_send6_flag(int s,const char *buf,size_t len,const char ip[16],uint16 port,uint32 scope_id,int flag)
 {
 #ifdef LIBC_HAS_IP6
   struct sockaddr_in6 si;
@@ -41,9 +41,13 @@ ssize_t socket_send6(int s,const char *buf,size_t len,const char ip[16],uint16 p
 #else
   si.sin6_scope_id=0;
 #endif
-  return winsock2errno(sendto(s,buf,len,0,(void*) &si,sizeof si));
+  return winsock2errno(sendto(s,buf,len,flag,(void*) &si,sizeof si));
 #else
   errno=EPROTONOSUPPORT;
   return -1;
 #endif
 }
+
+ssize_t socket_send6(int s,const char *buf,size_t len,const char ip[16],uint16 port,uint32 scope_id) {
+  return socket_send6_flag(s,buf,len,ip,port,scope_id,0);
+}