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When you open the Network Utility, you may be entering new territory because a lot of people don't go in here because they are not sure that they are going to understand what's happening in here, and even for normal users there is a lot of useful things that you can do within here. Some of it will be for IT sorts of people or people who spend a lot of time troubleshooting the niggling details of the network, but you as a normal user can also find some interesting things in here. The first thing we are going to look at is Ping. Pinging a computer is similar to poking your sleeping mate and asking "Are you awake? Ha, are you, ha, ha ,ha", except the computer being pinged isn't likely to slap you.
Essentially you are asking the remote computer to tell you if it is there by sending it a ping or a little packet of data and waiting for it to respond with the 'Yeah, I got it' message. There are a couple of useful things you can do with pinging, for example, if you are on the road you may want to know if your home server is running. If you have that Mac's IP address you just enter it in the network address field here and click Ping. If you see a response in the ping below you know it is alive and maybe even well. Also pinging a computer is a good way to tell if your firewall is working.
If you switch on the firewall in the Security System Preference so that it accepts only essential services or just those services you have allowed and a ping isn't one of them, that Mac should not reply to the ping which is good when you don't want other computers on the internet or locally talking to your Mac, so we are going to give this a try. I am going to ping my laptop and the address there is .255.72. I had the firewall configured so that it is open, so I will ping the computer and it should tell me that it's up and working.
And sure enough these little messages here are being sent back by the computer saying, yes, I am here and this is how long it took for me to do this. Now let's try this again, this time I am going to switch on the firewall, I will try to ping the computer and nothing will come back, let's see how that works, and sure enough it works. By this time we should have seen some kind of response if we were going to get one, we didn't get one because the firewall is switched on so if you are concerned that your firewall may not be working, this is one way to do it, and you don't have to ping another computer, you can also ping your own computer.
Simply enter your computer's IP address, which you can find in the Sharing System Preference, enter it here and click Ping, to ping your own computer. If you like to look up the IP address of a particular website, that's easily done as well, simply click Look Up, and enter the name of the domain you want to check. In this case let's check out lynda.com, find it what the IP address is. Click Look Up and there it is, here is the IP information about lynda.com. Now if you find that certain websites take forever to load on your Mac it is possible that your Mac is having to jump through several hoops to get there.
If you use traceroute, this will help confirm the length of the journey. Just enter the domain name or IP address in the network address field and click Trace. So we look for something like a www.guardian.co.uk so we are going to go to London on the strip and we will click Trace. And the journey is complete, click Stop, we will see where we have gone to trace the route. See we have been to San Jose, New York, London and we hopped a bunch of places in between.
So what good is this for you? This one may help you decide to change your ISP if yours is taking way too many trips to get where you wanted to go. Some ISPs have big pipes that go directly to places, others sort of take more secured routes and tend to be slower, and now to WhoIs. I moderate some message boards and I use WhoIs all the time to figure out where the people who post spam on our message boards are coming from. And it works much like the other network utility tabs. You enter a domain or an IP address in the address field and click WhoIs.
We will watch how that works. Now, let's go to the New York Times site for example, nyt.com. I will choose one of the services that reports these, how about network solutions, and click WhoIs, and here is our WhoIs information. This provides as much information as it can. You will actually get more information if you type in an IP address and let's see if they give us one somewhere. Indeed they do, here is our IP address here at the bottom, we will copy that, paste it up here, and now do another WhoIs search.
And now we will do another search but we use a different search body, in this case we will use arin.net, which I often have a lot of success with. Click WhoIs and we have more information. This is showing us the information for the ISP that handles that domain. Why this is important and useful is because of information like this, the abuse e-mail address. So for example, if you look into an e-mail message that you received, that has a lot of spam in it, if you look in the header information sometimes you can find the IP address of the person spamming you, you can then use a Look Up to find out who the ISP is, you can send an e-mail message to the abuse address and then hopefully they will be able to unplug that spammer's account and the spammer would be out of business at least until they can find a new ISP.
And finally port scan, this is another good option for testing a Mac's firewall. You can add in your Mac's IP address or local address in this field and click Scan, and we will give that a try. And this will tell me about the ports that are open on my Mac, and nothing appears to be open and the reason is because my firewall is on. Now let's turn off the firewall and see how it looks. And now we will scan the port again and see now that the firewall is off what it looks like.
And here we go; now we can see that certain ports are open. This is a good security measure if you know something about ports you can find out which ports are open on your Mac and if some show up, that you are a little concerned about, you can then use the firewall application to close those ports or you can use a firewall utility such as NoobProof to close specific ports. And that concludes our tour of Network Utility.
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