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Q&A: MacFixIt Answers

MacFixIt Answers is a weekly feature in which we answer questions e-mailed in by our readers. We welcome alternative approaches and views from readers and encourage you to post your own suggestions in the comments.

MacFixIt Answers is a feature in which we answer questions e-mailed in by our readers. This week we had questions on how the iTunes Home Sharing feature works, different approaches for upgrading to OS X Lion, how to list open network ports in OS X, and identifying whether or not you installed the Adobe Flash Trojan. We continually answer e-mail questions, and though we present a few answers here, we welcome alternative approaches and views from readers and encourage you to post your suggestions in the comments.

Question: How the iTunes home-sharing feature works
MacFixIt reader "Kski" asks:

I have a quick question regarding Home Sharing within iTunes. I am just now setting it up and I see that it says that I can stream my "iTunes library to my iPhone, iPad,... etc." My question is, "Is this actually streaming where it does not take up any space on that device?" Or is this where I can download songs onto my iPod Touch and then play them? Just a little confused on what home sharing is and if it is anything like the Pandora app?

Home Sharing is a streaming option if you choose to just play back files. It will not take up space on your mobile device; the file remains stored on your Mac and is fed in real time to your mobile device. However, it does support transferring files between your different devices if you would like to copy them.

Question: Different approaches for upgrading to Lion
MacFixIt reader "Jim B." asks:

I have not seen any info on the difference in the two choices:

  1. Using my SL, install Lion on my own, new, separately pre-partitioned volume that is big enuff for Lion AND my USER data.


  2. Use my Snow Leopard volume itself and install Lion on top of it.

In scenario 1, how does my USER (HOME) data get installed with Lion; and in scenario 2, won't there be a lot of extraneous data left over that Lion cannot use?

In the first scenario, the home folder will be migrated when you run Migration Assistant after booting to Lion for the first time. In the second scenario, there may be some stuff Lion will not be able to use, but any system software that is not needed will be removed by the Lion installer. Third-party software that is not supported will still remain and will need to be dealt with manually or by utilities provided by those developers.

Question: Listing open network ports in OS X
MacFixIt reader "Robert" asks:

How can i find out what ports are in use on my Mac (10.7) and what applications are using them?

You can get a list of open network ports by opening up Network Utility, selecting the Port Scan tab, and then entering "localhost" in the address field. From here you can either specify a port range or have it start from 0 and go through the whole 16-bit port range (up to 65535). The list should tell you what the port number is and what service is running on that port.

Question: How to tell whether you've installed the Adobe Flash Trojan
MacFixIt reader Karen asks:

It is entirely possible that I downloaded [the Adobe Flash Trojan]. I got a request to update and did so. System Preferences says I have version installed. However, if I did do the Trojan, how do I find out for sure, and how do I get rid of it? I am using Leopard and Firefox, so updating the "safe downloads list" won't do it - unless it is located somewhere other than what is in your article. I am not a technical person who is comfortable delving into system files, but if there is an article somewhere that can help out, or some sort of trustworthy software, I would be eternally grateful for some help.

If the update was an automatic one then you likely did not install the Trojan, as it appears to be a standalone installer that does not piggyback on any of Adobe's installed services (such as autoupdates). Nevertheless, to check, enter the following command into the Terminal, and if you see a listing that includes a number of "Google" entries, then you have installed the malware:

cat /etc/hosts

Luckily this file can be edited to remove the changes made by the malware (or you can restore it from a backup). To do this, enter "open /etc" in the Terminal to open the hidden "etc" folder. Then locate the "hosts" file and invoke Time Machine to restore a previous version of this file from before you installed the malware. If you do not have a Time Machine backup, then you can edit the file in a text editor like TextWrangler so that it only contains the following (copy and paste will work):

# Host Database
# localhost is used to configure the loopback interface
# when the system is booting.  Do not change this entry.
##	localhost	broadcasthost
::1             localhost 
fe80::1%lo0	localhost

Apple's Safe Downloads feature will work for all browsers, as it applies to any new application you are launching and not just to what you download through Safari. Therefore if you download malware through Firefox and try to run it, Apple's XProtect feature should identify it and give you a warning.

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