diff options
Diffstat (limited to 'Documentation/networking')
| -rw-r--r-- | Documentation/networking/ip-sysctl.txt | 29 |
1 files changed, 22 insertions, 7 deletions
diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt index d64e53124b8..c7fc1072494 100644 --- a/Documentation/networking/ip-sysctl.txt +++ b/Documentation/networking/ip-sysctl.txt @@ -467,16 +467,31 @@ 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 |