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diff --git a/share/man/man4/syncache.4 b/share/man/man4/syncache.4
--- a/share/man/man4/syncache.4
+++ b/share/man/man4/syncache.4
@@ -10,7 +10,7 @@
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
-.Dd April 12, 2021
+.Dd August 30, 2025
.Dt SYNCACHE 4
.Os
.Sh NAME
@@ -39,6 +39,8 @@
.Nm sysctl Cm net.inet.tcp.syncache.count
.It
.Nm sysctl Cm net.inet.tcp.syncache.see_other
+.It
+.Nm sysctl Cm net.inet.tcp.syncache.rst_on_sock_fail
.El
.Sh DESCRIPTION
The
@@ -107,6 +109,18 @@
set
.Va net.inet.tcp.syncookies_only
to 1.
+To use
+.Nm syncookies
+to handle bucket overflows in the
+.Nm syncache
+set
+.Va net.inet.tcp.syncookies
+to 1.
+The default value for
+.Va net.inet.tcp.syncookies_only
+is 0 and the default value for
+.Va net.inet.tcp.syncookies
+is 1.
.Pp
The
.Nm
@@ -169,6 +183,9 @@
.Xr ucred 9
referencing is required on every incoming SYN packet processed.
The default is off.
+.It Va rst_on_sock_fail
+Send a TCP RST segment if the socket allocation fails.
+The default is on.
.El
.Pp
Statistics on the performance of the
@@ -206,8 +223,16 @@
Failures to allocate new
.Nm
entry.
+.It Li "cookies sent"
+SYN cookies sent in SYN ACK segments.
.It Li "cookies received"
-Connections created from segment containing ACK.
+ACK segments with valid syncookies which resulted in TCP connection
+establishment.
+.It Li "spurious cookies rejected"
+Received ACKs, for which the syncache lookup failed and also no syncookie was
+recently sent.
+.It Li "failed cookies rejected"
+Received ACKs for which the syncookie validation failed.
.El
.Sh SEE ALSO
.Xr netstat 1 ,

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