vtund L2TP Connectivity To GENI

Installing the Prerequisite Software

vtund solution depends on two packages: vtun - virtual tunnel over TCP/IP, and bridge-utils - utilities for configuring Ethernet bridging. Both packages can be installed by using your favorite package manager. For example:

  apt-get install vtun bridge-utils

Seting up the Tunnel

Each tunnel has two servers as shown in Figure 1. landing1.orbit-lab.org is always assumed to be the master server while the other endpoint server is assumed to be the slave. Configuration files are somewhat different for the two servers and are described in following sections.

Bridge Configuration

Bridge interfaces need to be configured on both ends in order to connect LAN segments to the tunnel. This is achieved by creating a bridge and attaching it to the interface facing the internal LAN. The tunnel interface will be added to the bridge by the VTUN daemon once it establishes the tunnel. One way to configure the bridge is to use /etc/network/interfaces configuration file and assign unique addresses on each end. For this example we will configure bridge on the master side with IP address of 10.43.0.253/16 and bridge on the slave side with 10.43.21.253/16

/etc/network/interfaces on master

iface br0 inet static
 address 10.43.0.253
 netmask 255.255.0.0
 bridge_ports eth3

/etc/network/interfaces on slave

  auto br0
  iface br0 inet static 
  address 10.43.21.253
  netmask 255.255.0.0
  bridge_ports eth0

VTUN Master Configuration

/etc/default/vtun

RUN_SERVER=yes
SERVER_ARGS="-P 5000" 

Please note that server port numbers and password have to be coordinated with the Rutgers team.

/etc/vtund.conf

#
# VTun - Virtual Tunnel over TCP/IP network.
# Copyright (C) 1998-2001  Maxim Krasnyansky <max_mk@yahoo.com>
#...
# Lines which begin with '#' are comments

options {
    port 5000;            # Listen on this port.

    # Syslog facility
    syslog        daemon;

    # Path to various programs
    ifconfig      /sbin/ifconfig;
    route         /sbin/route;
    firewall      /sbin/iptables;
    ip            /sbin/ip;
}

default {
    compress no;
    encrypt no;
    speed 0;
}

slave1 {
    passwd XXXXXXXXX;
    type ether;
    proto udp;
    keepalive yes;
    compress no;
    encrypt no;

    up {
	# Connection is Up
	ifconfig "%% up";
	program "brctl addif br0 %%";
    };

    down {
	# Connection is Down
	ifconfig "%% down";
    };
}

VTUN Slave Configuration

/etc/default/vtun

RUN_SERVER=yes
# SERVER_ARGS="-P 5000"
CLIENT0_NAME=slave1
CLIENT0_HOST=128.6.192.147

/etc/vtund.conf

options {
    # Syslog facility
    syslog        daemon;

    # Path to various programs
    ifconfig      /sbin/ifconfig;
    route         /sbin/route;
    firewall      /sbin/iptables;
    ip            /sbin/ip;
}

default {
    compress no;
    encrypt no;
    speed 0;
}

slave1 {              
  passwd XXXXXXXXXXX;
  type  ether;          # Ethernet tunnel
  up {
        # Connection is Up
        ifconfig "%% up";
        program "brctl addif br0 %%";
  };
  down {
        # Connection is Down
        ifconfig "%% down";
  };
}

NOTE: Names of the tunnels have to match on both ends!