NAT Loopback Routers

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INTRODUCTION

What is NAT Loopback and why is it needed to host a public Opensimulator Region?

Currently (as at August 2010), a hosted region on a home connection with a broadband router needs, what is known as NAT Loopback functionality.

Simply put, it allows you to access an internal IP address in your home by the public IP address(the outside one given by your ISP). Symptoms of not having NAT Loopback is you can host a completely internal region(ie the region and asset database are all on one machine) and login, but someone outside can't login, even though you have set up your region.ini with your outside IP and forwarded the correct ports.

This page shows a list of routers supporting NAT Loopback feature in order to be able to TP in your region when you host it at home on the same computer or local network. Please, feel free to contribute such a list.

Please post to this list if your know a router is works with Opensimulator & Loopback or is known not to work.

D-Link

D-Link DGL-4500 series of routers have the largest available nat table of any router on the market.  These routers range from 70$-180$ USD depending on where you live and purchase from.

When considering a purchase, consider performance against cost. Upper end ADSL 2+ routers can add several Mbs to your modems sync speed.

Note: The DGL-4100 & DGL-4300 have been discontinued, and the replacement model is the DIL-825 and DIL-855 - Loopback status unknown on these later models. The DGL-4300 may be available second hand.

Netgear

Linksys/Cisco

3Com

  • 3CRWDR100A-72
  • 3CRWDR101A-75

Note: The WAG54G v2 NZ/Australia version has a faster processor, more memory and larger NAT table, and works with OS out of the box. Other market versions may not.


Other routers & Hardware

KNOWN non-functional for OpenSim:


REFERENCE LINKS:

More Information Related to Routers and Solutions @: osgrid.org/forums/viewtopic.php

SETTING UP A LINUX COMPUTER TO ACT AS A ROUTER


For Linux based Netfilter (iptables) routers, you want to set up the NAT table with some extra entries The following script is something to get you started, you'll need to fix up the variables at the top to match your system and network.
#!/bin/bash
#
# vvvvv - Fix these! - vvvvv
IPTABLES=/usr/sbin/iptables
LAN_NETWORK=192.168.0.0/24
SERVER_IP=192.168.0.2
INTERNET_IP=100.100.100.100
REMOTING_PORT=8895
REGION_PORT=9000
# ^^^^^ - Fix these! - ^^^^^
 
# First, the Destination NAT, anything going to the external address on our ports, we redirect to the server
# Note, if you have a double NAT running and this router doesn't actually have the internet IP address, you'll
# need another set of PREROUTING-DNAT lines with the --destination (-d) set to the internet facing private address
$IPTABLES -t nat -I PREROUTING -d $INTERNET_IP -p tcp --dport $REMOTING_PORT --jump DNAT --to-destination $SERVER_IP
$IPTABLES -t nat -I PREROUTING -d $INTERNET_IP -p udp --dport $REGION_PORT --jump DNAT --to-destination $SERVER_IP
$IPTABLES -t nat -I PREROUTING -d $INTERNET_IP -p tcp --dport $REGION_PORT --jump DNAT --to-destination $SERVER_IP
 
# Second, the Source NAT, we need this so that returning packets to our LAN clients go back through the router first,
# otherwise, the server will try to talk directly to the client and the client will reject them
$IPTABLES -t nat -I POSTROUTING -s $LAN_NETWORK -d $SERVER_IP -p tcp --dport $REMOTING_PORT --jump SNAT --to-source $INTERNET_IP
$IPTABLES -t nat -I POSTROUTING -s $LAN_NETWORK -d $SERVER_IP -p udp --dport $REGION_PORT --jump SNAT --to-source $INTERNET_IP
$IPTABLES -t nat -I POSTROUTING -s $LAN_NETWORK -d $SERVER_IP -p tcp --dport $REGION_PORT --jump SNAT --to-source $INTERNET_IP

--Hell Fire

openWRT Routers:

If you use openWRT firmware on your router, check here: OpenWRT NATLoopback

Windows XP Work Around:

Please see this -> http://vio.blpcomputers.info/loopbacknat.php

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