Explore the Network Utility

By Phil Davis
June 2015

Voila_Capture 2015-05-06_02-10-14_PMThis month, I want to explore one of the utility programs that come with your Mac – the Network Utility. We often forget about these little gems that we rarely need, but can be a lifesaver in times of trouble.

Many of these utilities are in the /Applications/Utilities folder, but some like the Network Utility are buried deeper in a system level folder that you rarely see: /System/Library/CoreServices/Applications/. This tool has been on the Mac for a long time and can be very useful for troubleshooting certain network problems.

Warning: This tip may be a little “geekier” that my usual tips, but don’t be frightened by the fact that it contains some technical jargon. There is no magic here and it can be worth your time to try the examples yourself.

To get started type “Network Utility” into Spotlight. After Network Utility opens you’ll see a single window with eight tabs. Let’s take a closer look at several of the tabs and learn what they do.

Info

The Info tab offers a drop-down menu of all your network interfaces. When you select one, you’ll see the Hardware Address, associated IP, speed, and information about how much data is going in and out of that particular connection.

 Ping

The Ping tool is usually the first one to use when you can’t get to the Internet. Think of this as “sonar” over the internet. When you send out a “ping” you are sending a small packet of data over the network to a specified address. This ping bounces back and shows how long it took to get to the destination.

By default, ping sends 10 packets, and then reports how many of those packets successfully arrived at the destination and how long it took those packets to make the trip. If you’re losing a lot of packets, or they take a long time to arrive, it’s a good sign that there’s a network slowdown. If you’re getting errors about all your packets, there’s probably a network problem on your side. To check if there are issues on your local network, you can ping your router’s address, which you can find in the Network preference pane (often 10.0.1.1 for Apple routers).

Example:

Sending a ping to the OMUG website (ocalamug.org) yields the following statistics – 10 packets transmitted, 10 packets received, 0.0% packet loss, round-trip avg = 87 ms.

If you look at the individual results for each of the 10 packets you can see times ranging from 70 ms up to 140 ms which is a result of each ping taking a different path over the Internet.

 Lookup

The Lookup tool is a handy one if you’ve ever had questions about just where an IP address comes from. Think of it like a phone book: Enter any domain name to get the corresponding IP address (or vice versa). If you find yourself wondering about where an email came from, the Lookup tool might provide some illumination.

Example:

If you enter ocalamug.org in the search box. You will get this: ocalamug.org -> 75.98.175.84.

If you go the other way and type this IP into the search box you will get: 75.98.175.84 -> a2s84.a2hosting.com. a2hosting is the name of the company that hosts our website.

Traceroute

Traceroute can be lots of fun as well as being useful when the network gets flaky. Think of Traceroute as an enhanced version of the ping tool — not only does it send packets to a specified server, but it shows all the intermiediate stops that packet makes. If there’s a particular server in the chain that’s slowing your connection down, Traceroute can help you find it. While you may not be able do anything about it directly, you can at least get an idea of where the problem exists.

Example:

If you enter the a2s84.a2hosting.com address, Traceroute started with the computer’s IP (10.0.1.1) and then took 14 more hops before it reached the final destination about 71 ms. later.

You can easily see where many of the hops go along the way – first to your ISP, then bouncing around the Internet until the final stop. Give this a try yourself to see what happens.

Whois

Finally, the Whois tool is the place to go if you’re wondering who owns a particular domain name. Just enter the domain name and scroll down to find a full listing about the owner of the domain. But many domains (including ocalamug.com) use anonomyzer services to provide privacy for the owner.

Example:

If you enter the 75.98.175.84 IP (address of the OMUG hosting contractor), you will see how this works. All the information about the owner of this domain will be displayed, including the name, address, and email of the contact person, and much more.

Now, take a few minutes to explore this utility on your own Mac. Luckily nothing you do with it will break anything – you won’t be responsible for shutting down the entire Internet for example. You can, however, learn a little bit more about this marvelous network that we take for granted. During coming months we will be looking at some of the other utilities that come with your Mac.