Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/linville/wirel...

[cascardo/linux.git] / Documentation / networking / ip-sysctl.txt

diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index ca447b3..c7fc107 100644 (file)
--- 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.