Add handle to control global TCP keepalives and turn them on as

default.

Despite their name it doesn't keep TCP sessions alive, it kills
them if the other end has gone AWOL.  This happens a lot with
clients which use NAT, dynamic IP assignment or which has a 2^32
* 10^-3 seconds upper bound on their uptime.

There is no detectable increase in network trafic because of this:
two minimal TCP packets every two hours for a live TCP connection.

Many servers already enable keepalives themselves.

The host requirements RFC is 10 years old, and doesn't know about
the loosing clients of todays InterNet.

8 files changed, 44 insertions, 8 deletions

diff --git a/etc/defaults/rc.conf b/etc/defaults/rc.conf
index b3874d6..a81058e 100644
--- a/etc/defaults/rc.conf
+++ b/etc/defaults/rc.conf
@@ -9,7 +9,7 @@
 #
 # All arguments must be in double or single quotes.
 #
-#	$Id: rc.conf,v 1.8 1999/04/10 10:56:56 des Exp $
+#	$Id: rc.conf,v 1.9 1999/05/16 09:19:44 phk Exp $
 
 ##############################################################
 ### Important initial Boot-time options  #####################
@@ -41,6 +41,7 @@ natd_interface="fxp0"           # Public interface or IPaddress to use.
 natd_flags=""                   # Additional flags for natd.
 tcp_extensions="NO"		# Set to Yes to turn on RFC1323 extensions.
 log_in_vain="NO"		# Disallow bad connection logging (or YES).
+tcp_keepalive="YES"		# Kill dead TCP connections (or NO).
 network_interfaces="lo0"	# List of network interfaces (lo0 is loopback).
 ifconfig_lo0="inet 127.0.0.1"	# default loopback device configuration.
 #ifconfig_lo0_alias0="inet 127.0.0.254 netmask 0xffffffff" # Sample alias entry.
diff --git a/etc/network.subr b/etc/network.subr
index a10e8fd..ef6bc08 100644
--- a/etc/network.subr
+++ b/etc/network.subr
@@ -1,6 +1,6 @@
 #!/bin/sh -
 #
-#	$Id: rc.network,v 1.43 1999/04/10 10:56:58 des Exp $
+#	$Id: rc.network,v 1.44 1999/04/12 15:26:41 brian Exp $
 #	From: @(#)netstart	5.9 (Berkeley) 3/30/91
 
 # Note that almost all the user-configurable behavior is no longer in
@@ -180,6 +180,11 @@ network_pass1() {
 	    sysctl -w net.inet.ip.accept_sourceroute=1 >/dev/null 2>&1
     fi
 
+    if [ "X$tcp_keepalive" = X"YES" ]; then
+	    echo -n ' TCP keepalive=YES'
+	    sysctl -w net.inet.tcp.always_keepalive=1 >/dev/null 2>&1
+    fi
+
     if [ "X$ipxgateway_enable" = X"YES" ]; then
 	    echo -n ' IPX gateway=YES'
 	    sysctl -w net.ipx.ipx.ipxforwarding=1 >/dev/null 2>&1
diff --git a/etc/rc.d/netoptions b/etc/rc.d/netoptions
index a10e8fd..ef6bc08 100644
--- a/etc/rc.d/netoptions
+++ b/etc/rc.d/netoptions
@@ -1,6 +1,6 @@
 #!/bin/sh -
 #
-#	$Id: rc.network,v 1.43 1999/04/10 10:56:58 des Exp $
+#	$Id: rc.network,v 1.44 1999/04/12 15:26:41 brian Exp $
 #	From: @(#)netstart	5.9 (Berkeley) 3/30/91
 
 # Note that almost all the user-configurable behavior is no longer in
@@ -180,6 +180,11 @@ network_pass1() {
 	    sysctl -w net.inet.ip.accept_sourceroute=1 >/dev/null 2>&1
     fi
 
+    if [ "X$tcp_keepalive" = X"YES" ]; then
+	    echo -n ' TCP keepalive=YES'
+	    sysctl -w net.inet.tcp.always_keepalive=1 >/dev/null 2>&1
+    fi
+
     if [ "X$ipxgateway_enable" = X"YES" ]; then
 	    echo -n ' IPX gateway=YES'
 	    sysctl -w net.ipx.ipx.ipxforwarding=1 >/dev/null 2>&1
diff --git a/etc/rc.d/network1 b/etc/rc.d/network1
index a10e8fd..ef6bc08 100644
--- a/etc/rc.d/network1
+++ b/etc/rc.d/network1
@@ -1,6 +1,6 @@
 #!/bin/sh -
 #
-#	$Id: rc.network,v 1.43 1999/04/10 10:56:58 des Exp $
+#	$Id: rc.network,v 1.44 1999/04/12 15:26:41 brian Exp $
 #	From: @(#)netstart	5.9 (Berkeley) 3/30/91
 
 # Note that almost all the user-configurable behavior is no longer in
@@ -180,6 +180,11 @@ network_pass1() {
 	    sysctl -w net.inet.ip.accept_sourceroute=1 >/dev/null 2>&1
     fi
 
+    if [ "X$tcp_keepalive" = X"YES" ]; then
+	    echo -n ' TCP keepalive=YES'
+	    sysctl -w net.inet.tcp.always_keepalive=1 >/dev/null 2>&1
+    fi
+
     if [ "X$ipxgateway_enable" = X"YES" ]; then
 	    echo -n ' IPX gateway=YES'
 	    sysctl -w net.ipx.ipx.ipxforwarding=1 >/dev/null 2>&1
diff --git a/etc/rc.d/network2 b/etc/rc.d/network2
index a10e8fd..ef6bc08 100644
--- a/etc/rc.d/network2
+++ b/etc/rc.d/network2
@@ -1,6 +1,6 @@
 #!/bin/sh -
 #
-#	$Id: rc.network,v 1.43 1999/04/10 10:56:58 des Exp $
+#	$Id: rc.network,v 1.44 1999/04/12 15:26:41 brian Exp $
 #	From: @(#)netstart	5.9 (Berkeley) 3/30/91
 
 # Note that almost all the user-configurable behavior is no longer in
@@ -180,6 +180,11 @@ network_pass1() {
 	    sysctl -w net.inet.ip.accept_sourceroute=1 >/dev/null 2>&1
     fi
 
+    if [ "X$tcp_keepalive" = X"YES" ]; then
+	    echo -n ' TCP keepalive=YES'
+	    sysctl -w net.inet.tcp.always_keepalive=1 >/dev/null 2>&1
+    fi
+
     if [ "X$ipxgateway_enable" = X"YES" ]; then
 	    echo -n ' IPX gateway=YES'
 	    sysctl -w net.ipx.ipx.ipxforwarding=1 >/dev/null 2>&1
diff --git a/etc/rc.d/network3 b/etc/rc.d/network3
index a10e8fd..ef6bc08 100644
--- a/etc/rc.d/network3
+++ b/etc/rc.d/network3
@@ -1,6 +1,6 @@
 #!/bin/sh -
 #
-#	$Id: rc.network,v 1.43 1999/04/10 10:56:58 des Exp $
+#	$Id: rc.network,v 1.44 1999/04/12 15:26:41 brian Exp $
 #	From: @(#)netstart	5.9 (Berkeley) 3/30/91
 
 # Note that almost all the user-configurable behavior is no longer in
@@ -180,6 +180,11 @@ network_pass1() {
 	    sysctl -w net.inet.ip.accept_sourceroute=1 >/dev/null 2>&1
     fi
 
+    if [ "X$tcp_keepalive" = X"YES" ]; then
+	    echo -n ' TCP keepalive=YES'
+	    sysctl -w net.inet.tcp.always_keepalive=1 >/dev/null 2>&1
+    fi
+
     if [ "X$ipxgateway_enable" = X"YES" ]; then
 	    echo -n ' IPX gateway=YES'
 	    sysctl -w net.ipx.ipx.ipxforwarding=1 >/dev/null 2>&1
diff --git a/etc/rc.d/routing b/etc/rc.d/routing
index a10e8fd..ef6bc08 100644
--- a/etc/rc.d/routing
+++ b/etc/rc.d/routing
@@ -1,6 +1,6 @@
 #!/bin/sh -
 #
-#	$Id: rc.network,v 1.43 1999/04/10 10:56:58 des Exp $
+#	$Id: rc.network,v 1.44 1999/04/12 15:26:41 brian Exp $
 #	From: @(#)netstart	5.9 (Berkeley) 3/30/91
 
 # Note that almost all the user-configurable behavior is no longer in
@@ -180,6 +180,11 @@ network_pass1() {
 	    sysctl -w net.inet.ip.accept_sourceroute=1 >/dev/null 2>&1
     fi
 
+    if [ "X$tcp_keepalive" = X"YES" ]; then
+	    echo -n ' TCP keepalive=YES'
+	    sysctl -w net.inet.tcp.always_keepalive=1 >/dev/null 2>&1
+    fi
+
     if [ "X$ipxgateway_enable" = X"YES" ]; then
 	    echo -n ' IPX gateway=YES'
 	    sysctl -w net.ipx.ipx.ipxforwarding=1 >/dev/null 2>&1
diff --git a/etc/rc.network b/etc/rc.network
index a10e8fd..ef6bc08 100644
--- a/etc/rc.network
+++ b/etc/rc.network
@@ -1,6 +1,6 @@
 #!/bin/sh -
 #
-#	$Id: rc.network,v 1.43 1999/04/10 10:56:58 des Exp $
+#	$Id: rc.network,v 1.44 1999/04/12 15:26:41 brian Exp $
 #	From: @(#)netstart	5.9 (Berkeley) 3/30/91
 
 # Note that almost all the user-configurable behavior is no longer in
@@ -180,6 +180,11 @@ network_pass1() {
 	    sysctl -w net.inet.ip.accept_sourceroute=1 >/dev/null 2>&1
     fi
 
+    if [ "X$tcp_keepalive" = X"YES" ]; then
+	    echo -n ' TCP keepalive=YES'
+	    sysctl -w net.inet.tcp.always_keepalive=1 >/dev/null 2>&1
+    fi
+
     if [ "X$ipxgateway_enable" = X"YES" ]; then
 	    echo -n ' IPX gateway=YES'
 	    sysctl -w net.ipx.ipx.ipxforwarding=1 >/dev/null 2>&1