/usr/sbin/fai-mk-network

#! /bin/bash

#*********************************************************************
#
# fai-mk-network -- setup a test network for FAI
#
# This script is part of FAI (Fully Automatic Installation)
# (c) 2015 by Thomas Lange, lange@informatik.uni-koeln.de
# Universitaet zu Koeln
#
#*********************************************************************

PATH=/sbin:/bin:/usr/sbin:/usr/bin

tapnum=9          # how many tap devies will be created
brip=192.168.33.1 # IP of bridge device
brname=br0
netdev=eth0       # network device used for routing to the outside internet

usage() {

    cat <<EOF
fai-mk-network, setup a test network for FAI

   Copyright (C) 2015 by Thomas Lange

Usage: fai-mk-network  {OPTIONS} USER

   -r                   Remove the network setup.
   -P                   Do not put the bridge into a private network

DESCRIPTION
fai-mk-network creates $tapnum tap devices which are added to a software bridge.
The tap devices will belong to the user specified. This bridge will be on a
private subnet ($brip/24) unless -P is specified. Also a NATing is enabled for
the private subnet. Using -P the bridge will use the network of $netdev instead
of a private subnet. Do not call this command in a network mounted directory
when using -P. You can configure different settings by modifying some variables
in the script itself.

Using fai-kvm(1) you can start virtual machines which are connected
to one of the tap devices.
EOF
    exit 0
}


mk_tap_devices() {

  for i in $(eval echo {1..$tapnum}); do
      [ -f /sys/class/net/tap$i/address ] && continue
      ip tuntap add dev tap$i mode tap user $user
      # when mixing tap devices and a real eth0 into a bridge, the
      # ethernet device should alsways have the lowest MAC address.
      # A bridge always uses the smallest/lowest MAC address when
      # doing dhcp requests. Make sure the tap devices have a high MAC address
      # change MAC address, so it begins with fX:
      mac=`sed -e 's/^./f/' /sys/class/net/tap$i/address`
      ip link set tap$i address $mac
  done
}

mk_bridge() {


    if [ $private -eq 0 ]; then
	dhclient -r $netdev
	ip addr flush $netdev            # remove IP address of real nic
	ip link set $netdev down
	ip link set $netdev name r$netdev
	brname=$netdev                   # use name of NIC for bridge
    fi

    brctl addbr $brname
    ip link set $brname up
    if [ $private -eq 0 ]; then
	brctl addif $brname r$netdev
	ip link set r$netdev up
	dhclient -v $netdev
    else
	ip addr add $brip/24 brd + dev $brname
    fi

    for i in $(eval echo {1..$tapnum}); do
	[ -f /sys/class/net/tap$i/address ] || continue
	brctl addif $brname tap$i          # add device to the bridge
	ip link set tap$i up
    done
}

rm_bridge() {

    for i in $(eval echo {1..$tapnum}); do
	[ -f /sys/class/net/tap$i/address ] || continue
	brctl delif $brname tap$i
	ip link set tap$i down
	ip tuntap del dev tap$i mode tap
    done

    if [ $private -eq 0 ]; then
	brname=$netdev                   # use name of NIC for bridge
	dhclient -r $netdev
	brctl delif $brname r$netdev
    fi


    ip link set $brname down
    ip addr flush $brname
    brctl delbr $brname

    if [ $private -eq 1 ]; then
	iptables -t nat -D POSTROUTING -o $netdev -j MASQUERADE
	sysctl -w net.ipv4.ip_forward=0
    else
	ip link set r$netdev down
	ip link set r$netdev name $netdev
	ip link set $netdev up
	dhclient -v $netdev
    fi
    exit 0
}


remove=0
private=1 # private network by default

while getopts Phr opt ; do
    case "$opt" in
        r) remove=1;;
        P) private=0 ;;
        h) usage ;;
        esac
done
shift $(($OPTIND - 1))

if [ $(id -u) != "0" ]; then
    echo "You must run this program as root."
    echo
    usage
fi

if [ ! -x "$(which brctl)" ]; then
    echo "brctl not found. Please install bridge-utils."
    exit 3
fi

if [ $remove -eq 1 ]; then
    rm_bridge
fi

if [ -z "$1" ]; then
    echo "Please add a user name which will own the tap devices."
    echo ""
    usage
fi
user=$1


mk_tap_devices
mk_bridge

# enable forward IP and do NATing
if [ $private -eq 1 ]; then
    sysctl -w net.ipv4.ip_forward=1
    iptables -t nat -I POSTROUTING -o $netdev -j MASQUERADE
fi


#  entry for /etc/network/interfaces:
#  auto br0
#  iface br0 inet static
#  address 192.168.33.1
#  netmask 255.255.255.0
#  bridge_ports regex (tap).*
fai-server 5.3.6ubuntu1 / usr / sbin / fai-mk-network
