From 359ce7f97e9ddd6082391def8f27ccceb31a83ce Mon Sep 17 00:00:00 2001
From: Felix Fietkau <nbd@openwrt.org>
Date: Wed, 31 Dec 2008 19:02:03 +0000
Subject: [PATCH] disable the MSS fixup hack by default (most ISPs don't
 require this as a workaround for MTU problems, only some do). this should
 give a nice speedup for routing on standard-compliant ISPs

SVN-Revision: 13788
---
 package/firewall/files/firewall.config | 5 +++++
 package/firewall/files/uci_firewall.sh | 5 ++++-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/package/firewall/files/firewall.config b/package/firewall/files/firewall.config
index e9035199fc..16d688e993 100755
--- a/package/firewall/files/firewall.config
+++ b/package/firewall/files/firewall.config
@@ -21,6 +21,11 @@ config forwarding
 	option src      lan
 	option dest     wan
 
+## Enable this option if you encounter any MTU problems
+## e.g. some websites work, others do not, submitting
+## forms causes problems, ...
+#	option mtu_fix	1
+
 
 ### EXAMPLE CONFIG SECTIONS
 # do not allow a specific ip to access wan
diff --git a/package/firewall/files/uci_firewall.sh b/package/firewall/files/uci_firewall.sh
index f46a533efd..41b2b5f76c 100755
--- a/package/firewall/files/uci_firewall.sh
+++ b/package/firewall/files/uci_firewall.sh
@@ -41,6 +41,7 @@ create_zone() {
 	config_set $ZONE_LIST $1 1 
 
 	$IPTABLES -N zone_$1
+	$IPTABLES -N zone_$1_MSSFIX
 	$IPTABLES -N zone_$1_ACCEPT
 	$IPTABLES -N zone_$1_DROP
 	$IPTABLES -N zone_$1_REJECT
@@ -60,6 +61,7 @@ addif() {
 	[ -n "$dev" -a "$dev" == "$1" ] && return
 	logger "adding $1 to firewall zone $2"
 	$IPTABLES -A input -i $1 -j zone_$2
+	$IPTABLES -I zone_$2_MSSFIX 1 -o $1 -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp-mss-to-pmtu
 	$IPTABLES -I zone_$2_ACCEPT 1 -o $1 -j ACCEPT
 	$IPTABLES -I zone_$2_DROP 1 -o $1 -j DROP
 	$IPTABLES -I zone_$2_REJECT 1 -o $1 -j reject
@@ -147,7 +149,6 @@ fw_defaults() {
 	$IPTABLES -A OUTPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
 	
 	$IPTABLES -A FORWARD -m state --state INVALID -j DROP
-	$IPTABLES -A FORWARD -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp-mss-to-pmtu
 	$IPTABLES -A FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT
 	
 	$IPTABLES -A INPUT -i lo -j ACCEPT
@@ -250,9 +251,11 @@ fw_forwarding() {
 
 	config_get src $1 src
 	config_get dest $1 dest
+	config_get_bool mtu_fix $1 mtu_fix 0
 	[ -n "$src" ] && z_src=zone_${src}_forward || z_src=forward
 	[ -n "$dest" ] && z_dest=zone_${dest}_ACCEPT || z_dest=ACCEPT
 	$IPTABLES -I $z_src 1 -j $z_dest
+	[ "$mtu_fix" -gt 0 -a -n "$dest" ] && $IPTABLES -I $z_src 1 -j zone_${dest}_MSSFIX
 }
 
 fw_redirect() {
-- 
2.25.1