More tcp_stdurg and SIOCATMARK work

man7/tcp.7

@@ -198,7 +198,7 @@ A maximum of (window/2^tcp_app_win, mss) bytes in the window
 are reserved for the application buffer.  A value of 0
 implies that no amount is reserved.
 .\"
-.\" The following is from 2.6.12: Doumentation/networking/ip-sysctl.txt
+.\" The following is from 2.6.12: Documentation/networking/ip-sysctl.txt
 .TP
 .BR tcp_bic " (Boolean; default: disabled)"
 Enable BIC TCP congestion control algorithm.
@@ -211,14 +211,14 @@ increment ensures linear RTT fairness as well as good
 scalability. Under small congestion windows, binary search
 increase provides TCP friendliness.
 .\"
-.\" The following is from 2.6.12: Doumentation/networking/ip-sysctl.txt
+.\" The following is from 2.6.12: Documentation/networking/ip-sysctl.txt
 .TP
 .BR tcp_bic_low_window " (integer; default: 14)"
 Sets the threshold window (in packets) where BIC TCP starts to
 adjust the congestion window. Below this threshold BIC TCP behaves
 the same as the default TCP Reno.
 .\"
-.\" The following is from 2.6.12: Doumentation/networking/ip-sysctl.txt
+.\" The following is from 2.6.12: Documentation/networking/ip-sysctl.txt
 .TP
 .BR tcp_bic_fast_convergence " (Boolean; default: enabled)"
 Forces BIC TCP to more quickly respond to changes in congestion
@@ -244,7 +244,7 @@ the TCP specification, but required to prevent
 denial-of-service attacks.  
 In Linux 2.2, the default value was 180.
 .\"
-.\" The following is from 2.6.12: Doumentation/networking/ip-sysctl.txt
+.\" The following is from 2.6.12: Documentation/networking/ip-sysctl.txt
 .TP
 .BR tcp_frto " (Boolean; default: disabled)"
 Enables F-RTO, an enhanced recovery algorithm for TCP retransmission
@@ -273,7 +273,7 @@ of 75 seconds apart) when keep-alive is enabled.
 Note that underlying connection tracking mechanisms and 
 application timeouts may be much shorter.
 .\"
-.\" The following is from 2.6.12: Doumentation/networking/ip-sysctl.txt
+.\" The following is from 2.6.12: Documentation/networking/ip-sysctl.txt
 .TP
 .BR tcp_low_latency  " (Boolean; default: disabled)"
 If enabled, the TCP stack makes decisions that prefer lower
@@ -425,13 +425,18 @@ in low-memory systems.
 Enable RFC2018 TCP Selective Acknowledgements. 
 .TP
 .BR tcp_stdurg " (Boolean; default: disabled)"
-Use the strict RFC793 interpretation of the TCP
-urgent-pointer field.  If this option is disabled, then use the
-BSD-compatible interpretation of the urgent-pointer, pointing
-to the first byte after the urgent data.  The RFC793
-interpretation is to have it point to the last byte of urgent
-data.  Enabling this option may lead to interoperability
-problems.
+If this option is enabled, then use the "strict" RFC793 interpretation
+of the TCP urgent-pointer field.
+(RFC793 was ambiguous in its specification of the meaning of the
+urgent pointer.
+Here, the "strict" interpretation means the
+one imposed by RFC961 and RFC1122.)
+According to this interpretation, the urgent pointer points
+to the last byte of urgent data.
+If this option is disabled, then use the BSD-compatible interpretation of 
+the urgent-pointer:
+the urgent pointer points to the first byte after the urgent data.
+Enabling this option may lead to interoperability problems.
 .TP
 .BR tcp_synack_retries " (integer; default: 5)"
 The maximum number of times a SYN/ACK segment
@@ -470,7 +475,7 @@ Enabling this option is not
 recommended since this causes problems when working
 with NAT (Network Address Translation). 
 .\"
-.\" The following is from 2.6.12: Doumentation/networking/ip-sysctl.txt
+.\" The following is from 2.6.12: Documentation/networking/ip-sysctl.txt
 .TP
 .BR tcp_tw_reuse " (Boolean; default: disabled)"
 Allow to reuse TIME-WAIT sockets for new connections when it is
@@ -491,7 +496,7 @@ employed.  If
 is disabled, TCP will not negotiate the use of window
 scaling with the other end during connection setup.
 .\"
-.\" The following is from 2.6.12: Doumentation/networking/ip-sysctl.txt
+.\" The following is from 2.6.12: Documentation/networking/ip-sysctl.txt
 .TP
 .BR tcp_vegas_cong_avoid  " (Boolean; default: disabled)"
 Enable TCP Vegas congestion avoidance algorithm.
@@ -501,7 +506,7 @@ adjusts the sending rate by modifying the congestion
 window. TCP Vegas should provide less packet loss, but it is
 not as aggressive as TCP Reno.
 .\"
-.\" The following is from 2.6.12: Doumentation/networking/ip-sysctl.txt
+.\" The following is from 2.6.12: Documentation/networking/ip-sysctl.txt
 .TP
 .BR tcp_westwood " (Boolean; default: disabled)"
 Enable TCP Westwood+ congestion control algorithm.
@@ -711,7 +716,8 @@ the urgent data (to actually read the urgent data requires the
 flag).
 .sp
 Note that a read never reads across the urgent mark.
-A program can thus advance up to the mark by performing reads 
+Thus, having obtained notification of the presence of urgent data, 
+a program can advance up to the mark by performing reads 
 (requesting any number of bytes) and testing
 .B SIOCATMARK
 after each read.