From 4a36a1b26f4cdc2dc3d06d7b3c4ac895b0083b2f Mon Sep 17 00:00:00 2001
From: mitty <mitty@7d2118f6-f56c-43e7-95a2-4bb3031d96e7>
Date: Wed, 1 Jul 2009 05:49:18 +0000
Subject: [PATCH]  * add a simple explanation to a script  * setnapt.sh    *
 script for setting up IP MASQUERADE

git-svn-id: https://lab.mitty.jp/svn/lab/trunk@8 7d2118f6-f56c-43e7-95a2-4bb3031d96e7
---
 iproute/setroute.sh |    5 ++++-
 iptables/setnapt.sh |   54 +++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 58 insertions(+), 1 deletion(-)
 create mode 100644 iptables/setnapt.sh

diff --git a/iproute/setroute.sh b/iproute/setroute.sh
index 668fc59..2ff477e 100644
--- a/iproute/setroute.sh
+++ b/iproute/setroute.sh
@@ -1,5 +1,8 @@
 #!/bin/sh
 
+# set individualized routing table and policy for each network device
+
+
 set -x
 
 ## INTERFACES(5)
@@ -28,7 +31,7 @@ fi
 
 # get IP address, network mask, default gateway info
 IPADDR=`/sbin/ip addr show dev ${IFACE} | grep -w inet | cut -d t -f 2 | cut -d ' ' -f 2 | cut -d / -f 1`
-if [ -z ${IPADDR} ]; then
+if [ -z "${IPADDR}" ]; then
     # fail to bind IP address to device
     echo "${IFACE} has no IP address."
     exit
diff --git a/iptables/setnapt.sh b/iptables/setnapt.sh
new file mode 100644
index 0000000..d34ba37
--- /dev/null
+++ b/iptables/setnapt.sh
@@ -0,0 +1,54 @@
+#!/bin/sh
+
+# set IP MASQUERADE for listed devices
+# this script must be set on the LAN gateway device
+
+
+set -x
+
+## INTERFACES(5)
+# IFACE  physical name of the interface being processed
+# METHOD method of the interface (e.g., static)
+# MODE   start if run from ifup, stop if run from ifdown
+# PHASE  as per MODE, but with finer granularity, distinguishing the pre-
+#        up, post-up, pre-down and post-down phases.
+
+# optional argument to set default gateway devices connected to WAN manually
+# (try each of them in order)
+GATEWAYS="$@"
+
+if [ "${PHASE}" = "post-down" ]; then
+    # flush POSTROUTING chain and exit
+    /sbin/iptables -t nat -F POSTROUTING
+    exit
+fi
+
+
+(
+
+# wait for initialization of WAN device with DHCPd 
+sleep 60
+
+if [ -z "${GATEWAYS}" ]; then
+    GATEWAYS=`/sbin/ip route show table main | grep -w default | cut -d ' ' -f 5`
+fi
+
+for GW in ${GATEWAYS}; do
+    if [ ${GW} = ${IFACE} ]; then
+        # skip if device is the LAN gateway
+        continue
+    fi
+    
+    IPADDR=`/sbin/ip addr show dev ${GW} | grep -w inet | cut -d t -f 2 | cut -d ' ' -f 2 | cut -d / -f 1`
+    if [ -z "${IPADDR}" ]; then
+        # device doesn't seem to have an IP address
+        break
+    fi
+    
+    ## set masquerade rule to all devices
+    #  because there is no way to know which one is default gateway
+    #  without manual specification
+    /sbin/iptables -t nat -A POSTROUTING -o ${GW} -j MASQUERADE
+done
+
+) &
-- 
1.7.9.5