[PATCH 1/3] kvm tools: Add a script to setup private bridge

[Amos Kong <kongjianjun@gmail.com>]

We can use this script to create/delete a private bridge,
and launch a dhcp server on the bridge by dnsmasq,
setup forware rule of iptable, then guest can access public network.

# ./set_private_br.sh vbr0 192.168.33
add new private bridge: vbr0
# brctl show
bridge name     bridge id               STP enabled     interfaces
vbr0            8000.000000000000       yes
# ifconfig vbr0
vbr0      Link encap:Ethernet  HWaddr 82:0f:f5:8f:92:47
          inet addr:192.168.33.1  Bcast:192.168.33.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:11 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:0 (0.0 B)  TX bytes:1979 (1.9 KB)
# ps aux |grep dnsmasq
nobody .. dnsmasq --strict-order --bind-interfaces --listen-address 192.168.33.1 \
--dhcp-range 192.168.33.1,192.168.33.254

Signed-off-by: Amos Kong <kongjianjun@gmail.com>
---
 tools/kvm/util/set_private_br.sh |   51 ++++++++++++++++++++++++++++++++++++++
 1 files changed, 51 insertions(+), 0 deletions(-)
 create mode 100755 tools/kvm/util/set_private_br.sh

diff --git a/tools/kvm/util/set_private_br.sh b/tools/kvm/util/set_private_br.sh
new file mode 100755
index 0000000..49867dd
--- /dev/null
+++ b/tools/kvm/util/set_private_br.sh
@@ -0,0 +1,51 @@
+#!/bin/bash
+#
+# Author: Amos Kong <kongjianjun@gmail.com>
+# Date: Apr 14, 2011
+# Description: this script is used to create/delete a private bridge,
+# launch a dhcp server on the bridge by dnsmasq.
+#
+# @ ./set_private_br.sh $bridge_name $subnet_prefix
+# @ ./set_private_br.sh vbr0 192.168.33
+
+brname='vbr0'
+subnet='192.168.33'
+
+add_br()
+{
+    echo "add new private bridge: $brname"
+    /usr/sbin/brctl addbr $brname
+    echo 1 > /proc/sys/net/ipv6/conf/$brname/disable_ipv6
+    echo 1 > /proc/sys/net/ipv4/ip_forward
+    /usr/sbin/brctl stp $brname on
+    /usr/sbin/brctl setfd $brname 0
+    ifconfig $brname $subnet.1
+    ifconfig $brname up
+    # Add forward rule, then guest can access public network
+    iptables -t nat -A POSTROUTING -s $subnet.254/24 ! -d $subnet.254/24 -j MASQUERADE
+    /etc/init.d/dnsmasq stop
+    /etc/init.d/tftpd-hpa stop 2>/dev/null
+    dnsmasq --strict-order --bind-interfaces --listen-address $subnet.1 --dhcp-range $subnet.1,$subnet.254 $tftp_cmd
+}
+
+del_br()
+{
+    echo "cleanup bridge setup"
+    kill -9 `pgrep dnsmasq|tail -1`
+    ifconfig $brname down
+    /usr/sbin/brctl delbr $brname
+    iptables -t nat -D POSTROUTING -s $subnet.254/24 ! -d $subnet.254/24 -j MASQUERADE
+}
+
+
+if [ $# = 0 ]; then
+    del_br 2>/dev/null
+    exit
+fi
+if [ $# > 1 ]; then
+    brname="$1"
+fi
+if [ $# = 2 ]; then
+    subnet="$2"
+fi
+add_br