diff --git a/weave b/weave
index ea6d9a9f..176461c5 100755
--- a/weave
+++ b/weave
@@ -73,10 +73,6 @@ add_iptables_rule() {
     fi
 }
 
-add_nat_rule() {
-    add_iptables_rule nat "$@"
-}
-
 create_bridge() {
     [ ! -d /sys/class/net/$BRIDGE ] && {
         ip link add name $BRIDGE type bridge
@@ -106,9 +102,9 @@ destroy_bridge() {
 
 setup_masquerading() {
     run_iptables -t nat -N WEAVE >/dev/null 2>&1 || true
-    add_nat_rule POSTROUTING -j WEAVE
-    add_nat_rule WEAVE -o $BRIDGE ! -s $1 -j MASQUERADE
-    add_nat_rule WEAVE -s $1 ! -o $BRIDGE -j MASQUERADE
+    add_iptables_rule nat POSTROUTING -j WEAVE
+    add_iptables_rule nat WEAVE -o $BRIDGE ! -s $1 -j MASQUERADE
+    add_iptables_rule nat WEAVE -s $1 ! -o $BRIDGE -j MASQUERADE
 }
 
 stop_masquerading() {
@@ -119,7 +115,7 @@ stop_masquerading() {
 
 # the following borrows from https://github.com/jpetazzo/pipework
 with_container_netns () {
-    CONTAINER="$2"
+    CONTAINER="$1"
     CONTAINER_PID=$(docker inspect --format='{{ .State.Pid }}' $CONTAINER)
 
     if [ "$CONTAINER_PID" = 0 ] ; then
@@ -144,6 +140,7 @@ with_container_netns () {
 
     # Run the wrapped command
     STATUS=0
+    shift 1
     if ! "$@" >$IP_TMPFILE 2>&1 ; then
         STATUS=1
         if [ "$(docker inspect --format='{{ .State.Pid }}' $CONTAINER)" != "$CONTAINER_PID" ] ; then
@@ -158,19 +155,16 @@ with_container_netns () {
     return $STATUS
 }
 
-# Attach Container-ID $1 to the weave network at CIDR address $2,
-# creating a virtual ethernet device if necessary.
-# Also turn off tx offload on device $3 inside the namespace.
 attach() {
     if ip link show $LOCAL_IFNAME >/dev/null 2>&1 ; then
         # veth name already exists, so assume we set it up already;
         # just add the IP address.
-        if ip netns exec $NETNS ip addr show dev $CONTAINER_IFNAME | grep -F $2 >/dev/null ; then
+        if ip netns exec $NETNS ip addr show dev $CONTAINER_IFNAME | grep -F $1 >/dev/null ; then
             # address was there already
             return 0
         fi
 
-        if ! ip netns exec $NETNS ip addr add $2 dev $CONTAINER_IFNAME ; then
+        if ! ip netns exec $NETNS ip addr add $1 dev $CONTAINER_IFNAME ; then
             return 1
         fi
 
@@ -181,40 +175,35 @@ attach() {
         return 1
     fi
 
-    if ! ip link set $LOCAL_IFNAME master $BRIDGE ||
-        ! ip link set $LOCAL_IFNAME up ||
-        ! ip link set $GUEST_IFNAME netns $NETNS ; then
+    if ! ip link set $GUEST_IFNAME netns $NETNS ; then
         # failed before we assigned the veth to the container's
         # namespace - delete it
         ip link del $LOCAL_IFNAME type veth || true
         return 1
     fi
 
-    if ! ip netns exec $NETNS ip link set $GUEST_IFNAME name $CONTAINER_IFNAME ||
-        ! ip netns exec $NETNS ip addr add $2 dev $CONTAINER_IFNAME ||
+    if ! ip link set $LOCAL_IFNAME master $BRIDGE ||
+        ! ip link set $LOCAL_IFNAME up ||
+        ! ip netns exec $NETNS ip link set $GUEST_IFNAME name $CONTAINER_IFNAME ||
+        ! ip netns exec $NETNS ip addr add $1 dev $CONTAINER_IFNAME ||
         ! ip netns exec $NETNS ip link set $CONTAINER_IFNAME up ||
-        ! check_command_and_run ethtool ip netns exec $NETNS ethtool -K $3 tx off >/dev/null ; then
+        ! check_command_and_run ethtool ip netns exec $NETNS ethtool -K $2 tx off >/dev/null ; then
         return 1
     fi
 
-    if ip netns exec $NETNS ip route show | grep '^224\.0\.0\.0/4' >/dev/null ; then
-        # There's a multicast route already present, leave it alone.
-        return 0
-    fi
-
     # Route multicast packets across the weave network.
-    ip netns exec $NETNS ip route add 224.0.0.0/4 dev $CONTAINER_IFNAME
+    if ! ip netns exec $NETNS ip route show | grep '^224\.0\.0\.0/4' >/dev/null ; then
+        ip netns exec $NETNS ip route add 224.0.0.0/4 dev $CONTAINER_IFNAME
+    fi
 }
 
-# Detach Container-ID $1 at CIDR address $2 from the weave network
-# removing the virtual ethernet device if there are no more addresses
 detach() {
-    if ! ip netns exec $NETNS ip addr show dev $CONTAINER_IFNAME | grep -F $2 >/dev/null ; then
+    if ! ip netns exec $NETNS ip addr show dev $CONTAINER_IFNAME | grep -F $1 >/dev/null ; then
         # address is not there, leave the device alone
         return 0
     fi
 
-    if ! ip netns exec $NETNS ip addr del $2 dev $CONTAINER_IFNAME ; then
+    if ! ip netns exec $NETNS ip addr del $1 dev $CONTAINER_IFNAME ; then
         return 1
     fi
 
@@ -230,7 +219,7 @@ detach() {
 case "$COMMAND" in
     launch)
         [ $# -gt 0 ] || usage
-        IPADDR=$1
+        CIDR=$1
         shift 1
         case $(docker inspect --format '{{ .State.Running }} {{ .Config.Image }}' weave 2>/dev/null) in
             "true $IMAGE")
@@ -251,7 +240,7 @@ case "$COMMAND" in
         esac
         create_bridge
         stop_masquerading
-        setup_masquerading $IPADDR
+        setup_masquerading $CIDR
         # We set the router name to the bridge mac since that is
         # stable across re-creations of the containers.
         #
@@ -263,7 +252,7 @@ case "$COMMAND" in
         # additional parameters, such as resource limits, to docker
         # when launching the weave container.
         CONTAINER=$(docker run --privileged -d --name=weave -p 6783:6783/tcp -p 6783:6783/udp $WEAVE_DOCKER_ARGS $IMAGE -name $MACADDR "$@" | tail -n 1)
-        with_container_netns attach $CONTAINER $IPADDR eth0
+        with_container_netns $CONTAINER attach $CIDR eth0
         echo $CONTAINER
         ;;
     status)
@@ -296,48 +285,43 @@ case "$COMMAND" in
         ;;
     run)
         [ $# -gt 0 ] || usage
-        IPADDR=$1
+        CIDR=$1
         shift 1
         create_bridge
         CONTAINER=$(docker run -d "$@" | tail -n 1)
-        with_container_netns attach $CONTAINER $IPADDR $CONTAINER_IFNAME
+        with_container_netns $CONTAINER attach $CIDR $CONTAINER_IFNAME
         echo $CONTAINER
         ;;
     start)
         [ $# -gt 1 ] || usage
-        IPADDR=$1
         create_bridge
         CONTAINER=$(docker start $2)
-        with_container_netns attach $CONTAINER $IPADDR $CONTAINER_IFNAME
+        with_container_netns $CONTAINER attach $1 $CONTAINER_IFNAME
         echo $CONTAINER
         ;;
     attach)
         [ $# -gt 1 ] || usage
         create_bridge
-        with_container_netns attach $2 $1 $CONTAINER_IFNAME
+        with_container_netns $2 attach $1 $CONTAINER_IFNAME
         ;;
     detach)
         [ $# -gt 1 ] || usage
-        with_container_netns detach $2 $1
+        with_container_netns $2 detach $1
         ;;
     expose)
         [ $# -gt 0 ] || usage
-        IPADDR=$1
-        shift 1
         create_bridge
-        if ! ip addr show dev $BRIDGE | grep -qF $IPADDR
+        if ! ip addr show dev $BRIDGE | grep -qF $1
         then
-            ip addr add dev $BRIDGE $IPADDR
+            ip addr add dev $BRIDGE $1
         fi
         ;;
     hide)
         [ $# -gt 0 ] || usage
-        IPADDR=$1
-        shift 1
         create_bridge
-        if ip addr show dev $BRIDGE | grep -qF $IPADDR
+        if ip addr show dev $BRIDGE | grep -qF $1
         then
-            ip addr del dev $BRIDGE $IPADDR
+            ip addr del dev $BRIDGE $1
         fi
         ;;
     stop)