TweetFollow Us on Twitter

Oct 99 Online

Volume Number: 15 (1999)
Issue Number: 10
Column Tag: MacTech Online

MacTech Online

by Jeff Clites <online@mactech.com>

Last month we started looking into some resources that can help you in setting up a small network, such as a home network to connect a few computers and printers. We found out that you can often cut your expenses by using an old Macintosh in place of new dedicated hardware, in this case to let you network a non-network printer, or expose a LocalTalk printer to an Ethernet network. Not only did we save some cash by using an old Mac, but also we made it possible to print from Mac OS X Server on a Blue and White G3, despite the limited connectivity options that platform currently supports. This month we're going to see how to use a single IP address to connect multiple machines to the outside world, again using an older Mac to do the real work.

Learning to Share: Network Address Translation

It's a pretty common problem - you only have one IP address available, but now you have more than one computer. So, you have to decide which one gets to use the modem, DSL line, or cable modem, or else you end up switching off and having to do a lot of plugging and unplugging of cables. Although it seems as though it shouldn't be possible, you actually can let all of your computers access the outside world at once through this single public IP address, thanks to a protocol known as Network Address Translation (NAT). In a nutshell, you assign arbitrary "private" IP addresses to the machines on your local network, and all communication to the outside world goes through a gateway machine (which can be a computer or a dedicated hardware device), which translates the source address in the header of the outgoing packets to your single public IP address, and it makes a note of this. Then, it reverses the process on incoming reply packets, so that they arrive at the proper local machine.

NAT is a capability built into most firewall products, and there are hardware devices which can act essentially as black boxes and do NAT for you, such as SonicWALL, BeadleNet's firewall routers, and Macsense's XRouter. These devices tend to be simple to set up and use, but are overkill if you just want to share an IP address - they are designed to do much more than just NAT, and their prices reflect this. A software-based approach is more economical, and it continues my theme of taking advantage of your legacy Macs. Both Vicomsoft and Sustainable Softworks have software solutions which perform NAT. Vicomsoft has several different products which include this along with their other functionality, but I chose IPNetRouter from Sustainable Softworks: there is no limit imposed on the number of computers you can connect through a single gateway, and it is low-cost (it is priced at $89), in part because it is simpler and a little more do-it-yourself. Also, there is a 50% educational discount available. I'm going to focus on IPNetRouter here, but you may want to check out the competition (both software- and hardware-based) for yourself.

SonicWALL
<http://www.sonicwall.com/>
BeadleNet
<http://www.beadlenet.com/>
Macsense XRouter
<http://www.macsensetech.com/Product/mih120.html>
Vicomsoft
<http://www.vicomsoft.com/>
Sustainable Softworks
<http://www.sustworks.com/>

Although IPNetRouter can seem a bit cryptic at first, if you just want to do NAT there are clear instructions on the company's web site, and you'll be up and running in just a few minutes. Your gateway machine can use either one or two Ethernet cards, and there are instructions on how to set up either configuration. The two-card setup is conceptually easier to understand, and offers a bit more security: one card connects to your local network and the other connects to the outside, so no information about your internal network configuration can leak to the outside world without going through IPNetRouter. Ethernet cards are cheap, so you may want to opt for this setup.

Getting Started with IPNetRouter
<http://www.sustworks.com/products/ipnr/gettingstarted/Guide.html>

This brings up another benefit of NAT: your gateway machine acts in part as a firewall, hiding your internal network from the outside world. In fact, from the outside it will appear as though there is only a single computer involved. This, in itself, makes it difficult to break into your internal computers; your private LAN can access the public internet, but not the other way around. If you want to go a little further and add some additional security measures, Sustainable Softworks has a page entitled Building Your Own Low Cost Firewall which will help you set up IPNetRouter for this. Finally, you can do almost the opposite, and "punch a hole" in your configuration to allow, for instance, a web server to operate from inside of your network. To do this, you set up IPNetRouter to do inbound port mapping, which routes all traffic destined for a particular port at your public IP address to a particular port on a particular machine on your internal network. This allows machines on the public internet to initiate connections to your internal web server; they think they are connecting to, say, port 80 of your gateway machine, but really they are being served web pages from port 80 (or another port of your choosing) of in internal machine. You'll probably need to do similar port mapping to use the QuickTime Streaming Server (but client machines can receive streaming QuickTime 4 content without any special configuration - support for this is built-in).

Building Your Own Low Cost Firewall
<http://www.sustworks.com/products/ipnr/gettingstarted/firewall.html>
Port Mapping
<http://www.sustworks.com/products/ipnr/gettingstarted/port_mapping.html>

So, for less than $90 I can connect multiple computers to the internet, and set up firewall protection for a web server. That's not bad, and best of all, it's fast. In my home setup, I'm using a PowerMac 7500/150 as my gateway, and there's no noticeable slowdown compared to when my internal Mac is connected directly to my DSL line. Part of the reason that IPNetRouter is fast is that it is Open Transport native (in fact, most of its capabilities are built into Open Transport already, and IPNetRouter just provides a way to configure them). But you also have to remember that this isn't a computationally intensive task - I believe that Cisco routers still use 68K-based processors. So even an old 68K Mac should give pretty good performance.

The pages mentioned above do a pretty good job of introducing you to concepts such as NAT, firewalls, and port mapping. You can get some more information on NAT from the KnowledgeShare section of Vicomsoft's site, or you can go directly to the RFCs and get the details.

Vicomsoft KnowledgeShare: Network Address Translation
<http://www.vicomsoft.com/knowledge/reference/nat.html>
RFC1631 - The IP Network Address Translator (NAT)
<http://www.faqs.org/rfcs/rfc1631.html>
RFC2663 - IP Network Address Translator (NAT) Terminology and Considerations
<http://www.faqs.org/rfcs/rfc2663.html>

So, again we've found a strategy that lets us use a spare Macintosh to save us the expense of buying new hardware to set up our network, adding IP sharing to our bag of tricks to go along with the printer sharing techniques we learned last month. Also, we've again solved a problem that developers will be especially likely to face: even if you plan to use only a single computer, if you are using Mac OS X Server then you currently need a second IP address in order to access the internet from the Blue Box. With a NAT setup this is no longer a problem, and you can use last month's printing trick at the same time by running Apple's LocalTalk Bridge on your gateway along with IPNetRouter - they seem to play well together.

As a final note, when you run into snags you should check out the Three Macs and a Printer web site, which contains a wealth of information about setting up a small network, and explains everything in simple terms. It covers many topics that I have not been able to touch upon, and it has recently settled in to its very own domain.

Three Macs & a Printer
<http://www.threemacs.com/network/index.html>

When you get tired of connecting everything together, take a gander at the other links available from the MacTech Online web pages at <www.mactech.com/online/>.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

The beginner's guide to Warbits
Warbits is a turn-based strategy that's clearly inspired by Nintendo's Advance Wars series. Since turn-based strategy games can be kind of tricky to dive into, see below for a few tips to help you in the beginning. Positioning is crucial [Read... | Read more »
How to upgrade your character in Spellsp...
So you’ve mastered the basics of Spellspire. By which I mean you’ve realised it’s all about spelling things in a spire. What next? Well you’re going to need to figure out how to toughen up your character. It’s all well and good being able to spell... | Read more »
5 slither.io mash-ups we'd love to...
If there's one thing that slither.io has proved, it's that the addictive gameplay of Agar.io can be transplanted onto basically anything and it will still be good fun. It wouldn't be surprising if we saw other developers jumping on the bandwagon,... | Read more »
How to navigate the terrain in Sky Charm...
Sky Charms is a whimsical match-'em up adventure that uses creative level design to really ramp up the difficulty. [Read more] | Read more »
Victorious Knight (Games)
Victorious Knight 1.3 Device: iOS Universal Category: Games Price: $1.99, Version: 1.3 (iTunes) Description: New challenges awaits you! Experience fresh RPG experience with a unique combat mechanic, packed with high quality 3D... | Read more »
Agent Gumball - Roguelike Spy Game (Gam...
Agent Gumball - Roguelike Spy Game 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: Someone’s been spying on Gumball. What the what?! Two can play at that game! GO UNDERCOVERSneak past enemy... | Read more »
Runaway Toad (Games)
Runaway Toad 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: It ain’t easy bein’ green! Tap, hold, and swipe to help Toad hop to safety in this gorgeous new action game from the creators of... | Read more »
PsyCard (Games)
PsyCard 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: From the makers och Card City Nights, Progress To 100 and Ittle Dew PSYCARD is a minesweeper-like game set in a cozy cyberpunk... | Read more »
Sago Mini Robot Party (Education)
Sago Mini Robot Party 1.0 Device: iOS Universal Category: Education Price: $2.99, Version: 1.0 (iTunes) Description: -- Children's Technology Review Editor's Choice -- | Read more »
Egz – The Origin of the Universe (Games...
Egz – The Origin of the Universe 1.0.2 Device: iOS Universal Category: Games Price: $3.99, Version: 1.0.2 (iTunes) Description: ►►► Special offer until 2nd may : get the game at 2.99€ instead of 3.99€ ! ◄◄◄ Egz is a mesmerizing mix... | Read more »

Price Scanner via MacPrices.net

Mac minis on sale for up to $100 off MSRP
B&H Photo has Mac minis on sale for up to $100 off MSRP including free shipping plus NY sales tax only: - 1.4GHz Mac mini: $449 $50 off MSRP - 2.6GHz Mac mini: $649 $50 off MSRP - 2.8GHz Mac mini... Read more
13-inch Retina MacBook Pros on sale for up to...
B&H Photo has 13″ Retina MacBook Pros on sale for $130-$200 off MSRP. Shipping is free, and B&H charges NY tax only: - 13″ 2.7GHz/128GB Retina MacBook Pro: $1169 $130 off MSRP - 13″ 2.7GHz/... Read more
Apple price trackers, updated continuously
Scan our Apple Price Trackers for the latest information on sales, bundles, and availability on systems from Apple’s authorized internet/catalog resellers. We update the trackers continuously: - 15″... Read more
SanDisk Half-Terabyte SSD Optimized for Every...
SanDisk Corporation has announced the SanDisk Z410 SSD, a cost-competitive, half-terabyte solid state drive (SSD) that enables manufacturers to design for a broad range of desktop PCs and laptops.... Read more
Churchill Downs Racetrack Selects VenueNext t...
Churchill Downs Racetrack has announced an agreement with VenueNext to implement its technology platform for the start of Churchill Downs 2016 Spring Meet, which includes the 142nd running of the... Read more
Record 700 Million Pounds of CE Recycled in 2...
The Consumer Technology Association (CTA) reports that a record-setting 700 million pounds of consumer electronics (CE) have been recycled under the eCycling Leadership Initiative (ELI). According to... Read more
Price drops on clearance 12-inch Retina MacBo...
B&H Photo has dropped prices on leftover 2015 12″ Retina MacBooks with models now available starting at $999. Shipping is free, and B&H charges NY tax only: - 12″ 1.1GHz Gray Retina MacBook... Read more
15-inch Retina MacBook Pros available for $20...
B&H Photo has 15″ Retina MacBook Pros on sale for up to $210 off MSRP. Shipping is free, and B&H charges NY tax only: - 15″ 2.2GHz Retina MacBook Pro: $1799 $200 off MSRP - 15″ 2.5GHz Retina... Read more
Target offers Apple Watch Sport for $50 off M...
Target has Apple Watch Sports on sale for $50 off MSRP for a limited time. Choose free shipping or free local store pickup (if available). Sale prices for online orders only, in-store prices may vary... Read more
Apple restocks Certified Refurbished Mac mini...
Apple has restocked Certified Refurbished 2014 Mac minis, with models available starting at $419. Apple’s one-year warranty is included with each mini, and shipping is free: - 1.4GHz Mac mini: $419 $... Read more

Jobs Board

*Apple* Retail - Multiple Positions - Apple,...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
Restaurant Manager (Neighborhood Captain) - A...
…in every aspect of daily operation. WHY YOU'LL LIKE IT: You'll be the Big Apple . You'll solve problems. You'll get to show your ability to handle the stress and Read more
Restaurant Manager (Neighborhood Captain) - A...
…in every aspect of daily operation. WHY YOU'LL LIKE IT: You'll be the Big Apple . You'll solve problems. You'll get to show your ability to handle the stress and Read more
Simply Mac *Apple* Specialist- Service Repa...
Simply Mac is the largest premier retailer of Apple products in the nation. In order to support our growing customer base, we are currently looking for a driven Read more
*Apple* Retail - Multiple Positions - Apple,...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.