X-Git-Url: http://pileus.org/git/?a=blobdiff_plain;f=Documentation%2Fnetworking%2Fip-sysctl.txt;h=c7fc10724948629c98100b19250f8ee07d9dcd73;hb=eb0ad9c06d51edb5d18a7007fd4d77a8805b2ba7;hp=ca447b35b8333106cdd19649d943d80cdb12cc1e;hpb=8a06bf14008fbf55a86105b8569494f4beeb8762;p=~andy%2Flinux

diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index ca447b35b83..c7fc1072494 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -439,7 +439,9 @@ tcp_stdurg - BOOLEAN
 tcp_synack_retries - INTEGER
 	Number of times SYNACKs for a passive TCP connection attempt will
 	be retransmitted. Should not be higher than 255. Default value
-	is 5, which corresponds to ~180seconds.
+	is 5, which corresponds to 31seconds till the last retransmission
+	with the current initial RTO of 1second. With this the final timeout
+	for a passive TCP connection will happen after 63seconds.
 
 tcp_syncookies - BOOLEAN
 	Only valid when the kernel was compiled with CONFIG_SYNCOOKIES
@@ -465,20 +467,37 @@ tcp_syncookies - BOOLEAN
 tcp_fastopen - INTEGER
 	Enable TCP Fast Open feature (draft-ietf-tcpm-fastopen) to send data
 	in the opening SYN packet. To use this feature, the client application
-	must not use connect(). Instead, it should use sendmsg() or sendto()
-	with MSG_FASTOPEN flag which performs a TCP handshake automatically.
-
-	The values (bitmap) are:
-	1: Enables sending data in the opening SYN on the client
-	5: Enables sending data in the opening SYN on the client regardless
-	   of cookie availability.
+	must use sendmsg() or sendto() with MSG_FASTOPEN flag rather than
+	connect() to perform a TCP handshake automatically.
+
+	The values (bitmap) are
+	1: Enables sending data in the opening SYN on the client.
+	2: Enables TCP Fast Open on the server side, i.e., allowing data in
+	   a SYN packet to be accepted and passed to the application before
+	   3-way hand shake finishes.
+	4: Send data in the opening SYN regardless of cookie availability and
+	   without a cookie option.
+	0x100: Accept SYN data w/o validating the cookie.
+	0x200: Accept data-in-SYN w/o any cookie option present.
+	0x400/0x800: Enable Fast Open on all listeners regardless of the
+	   TCP_FASTOPEN socket option. The two different flags designate two
+	   different ways of setting max_qlen without the TCP_FASTOPEN socket
+	   option.
 
 	Default: 0
 
+	Note that the client & server side Fast Open flags (1 and 2
+	respectively) must be also enabled before the rest of flags can take
+	effect.
+
+	See include/net/tcp.h and the code for more details.
+
 tcp_syn_retries - INTEGER
 	Number of times initial SYNs for an active TCP connection attempt
 	will be retransmitted. Should not be higher than 255. Default value
-	is 5, which corresponds to ~180seconds.
+	is 6, which corresponds to 63seconds till the last restransmission
+	with the current initial RTO of 1second. With this the final timeout
+	for an active TCP connection attempt will happen after 127seconds.
 
 tcp_timestamps - BOOLEAN
 	Enable timestamps as defined in RFC1323.