diff options
Diffstat (limited to 'Documentation/networking/ip-sysctl.txt')
| -rw-r--r-- | Documentation/networking/ip-sysctl.txt | 37 |
1 files changed, 28 insertions, 9 deletions
diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt index ca447b35b833..c7fc10724948 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. |