Networking Notes: Free (and Almost Free) Mac Networking Tools

Friday Jun 8th 2007 by Michael Hall

This week we look at two handy, free tools that make using Macs a little nicer for practical networkers. And we take a peek at one that costs a little, but offer good value.

There's a common lament among people who switch to Macs, especially those coming over from the Linux and Unix worlds, that goes something like this: "Mac people are willing to drop an insane amount of money for software I took for granted (and got for free) on my old platform! What gives?"

If the Mac was a terrible development platform, that'd be a problem. But Apple does a pretty good job of providing remarkably useful tools for developers to build good software with a minimum of fuss. If you own a Mac, you own a good development environment in Xcode. That has resulted in a good shareware market full of robust apps. It also so happens that it's created a pretty good freeware market, too.

So this week we're going to look at two handy, free tools that make Mac living a little nicer for practical networkers, and we're going to throw in one that costs a little but delivers good functionality, especially for laptop users.

First up is AP Grapher, a free (donations accepted) wireless monitor from Chimoosoft. It's a simple tool that handles two basic tasks: It discovers Wi-Fi networks operating in your area, and it graphs the connection quality for the access point your system's connected to.

Wireless networking on the Mac is a simple proposition, especially when it comes to detecting local access points. AP Grapher provides a few extras over simply bringing up the wireless mini-menu in your taskbar and seeing what's out there. It provides detailed information on each access point it detects, including highest and lowest signal strength, its overall availability over time, and which Wi-Fi channel it's operating on.

That last metric is great if you're trying to assess spotty performance from your own access point. Though there are 11 Wi-Fi channels available, it's generally agreed that it's best to stick to channel 1, 6 or 11 when you're setting up a WAP to avoid interference from adjacent channels.

By firing up AP Grapher and taking a look at the channels neighboring access points are operating on, you can get a good sense of your best choice. In my neighborhood, for instance, I can consistently spot three other access points. AP Grapher told me all three were operating on channels 9, 10 and 11. I don't know what that's doing to their throughput, but I do know I've got a strong incentive to set my own WAP to use channel 1 or 6.

AP Grapher's other key function is its signal graphing. It allows users to monitor several key signal metrics, including transmission rate, noise, signal-to-noise ratio and signal strength. It includes a marking tool, which makes it easy to troubleshoot for potential interference from other devices.

There are nicer wireless site profiling tools out there, but for a practical networker who's just trying to make good choices when it comes time to set up a WAP, AP Grapher is a good pick.

Next up is Shimo, an app I've come to appreciate over the past year. It provides an easy, friendly interface to the Cisco VPN client. If you have to use that particular piece of software, you should be all ears. If you don't, well, bookmark it in case you ever have to.

The Cisco client itself has one of the less elegant interfaces out there. It's not particularly attractive, and it has a huge window for doing a fairly simple thing, and it has the irritatingly un-Maclike habit of shutting down if you close the main window. In other words, if you habitually use ⌘-w to close a window you need to unlearn that habit, because it shuts the Cisco VPN client down completely, so minimize or die.

Shimo offers a fix for that by providing a simple, unobtrusive mini-menu that sits up in the task bar and does just a few things very well: It offers a simple interface to connect to a VPN (you click Shimo's icon, then you click "Connect"), it provides some basic connection statistics (if you're into that), and it provides an interface to the Growl messaging system, which means you can set it to provide nonintrusive notifications when you connect, get disconnected or need to read the message of the day from your VPN administrator.

It doesn't free you of having to have a proper installation of the Cisco VPN client on your Mac, but it does offer a way out of ever having to launch it again.

Finally, we've got Postfix Enabler, which is not free (it costs $9.95) but which provides an invaluable service to Mac laptop users and anyone who'd like to run an SMTP listener on a Mac instead of dealing with an ISP's.

OS X ships with a perfectly good SMTP daemon (Postfix), but doesn't enable it by default. That's probably a good thing, to the extent the average person shouldn't be running a service like that without knowing exactly how to manage and secure it. There are a number of tutorials that address how to get Postfix configured and running, but for a Mac user who's feeling a little phobic about the command line, they're not so helpful.

Postfix Enabler provides a GUI interface that configures Postfix and then turns it on or off. Unlike the freeware RapidoSMTP, Postfix Enabler offers a lot of customization to overcome some problems home networkers often face when they're trying to run an SMTP server from a consumer line or laptop.

One key feature Postfix Enabler offers is SMTP masquerading. Simply put, SMTP masquerading allows your computer to appear to be sending mail from the same domain as your mail headers themselves say they are. If, for instance, you have a DSL connection from Joe's Pretty Good ISP that causes your traffic to appear to be originating from a machine within the network, but you have your own domain, say, your mail will provide a quandary for other SMTP listeners: It'll claim to be written by, but it will also show that it originated from your-computer' That looks like a forgery to many SMTP listeners, and they'll bounce or quietly discard the message on the premise that it's likely spam. While that scenario isn't necessarily a big problem for home networkers, it can definitely be an issue for laptop users who send mail from a number of networks.

Postfix Enabler also exposes Postfix's smarthost capabilities, which allow you the convenience of running a local SMTP daemon, but actually forward traffic from it to an ISP or business's SMTP host for distribution, which gives you some benefits in terms of your mail's credibility with other SMTP hosts.

Both of those features get home or small business owners around the complications posed by an increasingly paranoid Internet when it comes to handling mail traffic from consumer-grade connections.

It also bears noting that Postfix Enabler can drive configuration of an IMAP or POP3 server on a given Mac, as well. I didn't look into this functionality and can't comment on how well it works. The underlying technology is robust, though, so if you're looking to turn a Mac on your LAN into a full-fledged mail server, Postfix Enabler might be the ticket.

For $9.95, Postfix Enabler is a decent bargain. I've configured a few Postfix servers in my time, but I've treated my license as a convenience tax over the course of three laptops and two ISP changes.

Adapted from, part of the Network.

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