diff --git a/lib/iptables.inc b/lib/iptables.inc
index 4d270db..e2f7d9d 100644
--- a/lib/iptables.inc
+++ b/lib/iptables.inc
@@ -179,13 +179,16 @@ function enable_mss_clamp {
 			[[ ${mss} != "-" ]] && mss="-m tcpmss --mss ${mss}"
 			[[ ${mss} == "-" ]] && mss=""
 			[[ -z ${type} ]] && type="-"
-			[[ ${type} == "-" ]] && type="${OutFilter}"
+			[[ ${type} == "-" ]] && type="out"
 			[[ ${type} == "out" ]] && type="${OutFilter}"
 			[[ ${type} == "fwd" ]] && type="${FwdFilter}"
+			[[ ${type} == "in" ]] && type="${InFilter}"
 			[[ -z ${msssize} ]] && msssize="-"
 			[[ ${msssize} != "-" ]] && msssize="--set-mss ${msssize}"
 			[[ ${msssize} == "-" ]] && msssize="--clamp-mss-to-pmtu"
-			[[ ${interface} != "all" ]] && interface="-o ${interface}"
+			#[[ ${interface} != "all" ]] && interface="-o ${interface}"
+			[[ ${type} == "${InFilter}" ]] && interface="-i ${interface}"
+			[[ ${type} == "${OutFilter}" ]] && interface="-o ${interface}"
 			[[ ${interface} == "all" ]] && interface=""
 			${debug} ${DebugColor} "${FUNCNAME}:${DEFAULT_COLOR} Read: ${interface} ${mss} ${type} ${msssize}"
 			${VER_IPTABLES} -A ${type} -p tcp --tcp-flags SYN,RST SYN -j TCPMSS \