macosxhints.com network tips

"Airplane mode" for OS X

Mon, 25 Mar 2013 07:30:00 -0700

A reader at Stack Exchange asked an interesting question about whether it was possible to set up an "airplane mode" for OS X. The idea was to ensure that there is no network activity through any possible network interfaces.

It's actually pretty simple to do this. If you go to the Network pane of System Preferences, you'll see a Location popup menu at the top of the window. Click on that menu and choose Edit Locations. Click on the + icon to add a new location, then enter a name, such as AirplaneMode. Click on Done.

Next, choose that location in the Location menu, and click on each available network interface in the list at the left of the window. Click on the Configure iPv4 menu, and choose Off. For Wi-Fi, just click on the Turn Wi-Fi Off button. Click Apply, and this location will block all network activity.

To activate the location, ther ...

Generate list of wi-fi networks a Mac has used

Thu, 27 Dec 2012 07:30:00 -0800

You can find out which wi-fi networks a Mac has connected to by going to the Network preference pane, then clicking on Advanced, then on the Wi-Fi tab; they'll be listed in Preferred Networks. But if you want to do this from Terminal - say for a Mac you've connected to via ssh - this hint, posted on OS X Daily, can do it as well:

defaults read /Library/Preferences/SystemConfiguration/com.apple.airport.preferences RememberedNetworks | egrep -o '(SSID_STR|_timeStamp).+' | sed 's/^.*= \(.*\);$/\1/' | sed 's/^"\(.*\)"$/\1/' | sed 's/\([0-9]\{4\}-..-..\).*/\1/'

The list will be the same as that in Preferred Networks, and you can't alter it, ...

Use Back to My Mac to manage remote server

Fri, 16 Nov 2012 07:30:00 -0800

When managing a server at work, I noticed my home server was showing up in the list of managed servers. Trying to see if I could connect by supplying my credentials was unsuccessful. I figured it must be showing up because I had signed into the same iCloud account on both machines. I then wondered if using the Back to My Mac URL for iCloud would allow me to connect.

To test, in Server.app I selected Manage > Connect to Server... From there chose "Other Mac." For the Hostname I inserted the Back to My Mac URL in the form server.XXXXXXXX.members.btmm.icloud.com. (see this hint to find how to construct the correct URL for your Mac), supplied my credentials and clicked Connect. The remote server came right up and I was able to manage my home server with no issues.

Option-click Airport menu to launch Wi-Fi Diagnostics

Thu, 06 Sep 2012 07:30:00 -0700

A hint last year mentioned Wi-Fi Diagnostics, an application hidden in /System/Library/CoreServices. It turns out that you can also access this by Option-clicking the AirPort menu in your menubar and choosing Open Wi-Fi Diagnostics.

[kirkmc adds: This was available under Lion, but wasn't in the original hint, so it's worth posting.]

Remotely connect to a Mac via SSH using iCloud's network

Fri, 10 Aug 2012 07:30:00 -0700

If you're running two Macs with iCloud support (Lion or Mountain Lion), then you can use iCloud's network to remote SSH back into your home computer no matter where you are with just a few commands in Terminal.

The process is explained by the One Thing Well blog, but you need to set up a few things before you get started. First, you need to make sure Back to My Mac is enabled in iCloud (System Preferences > iCloud > Back to My Mac). Next, you need to set up your home computer for sharing if it isn't already. Head to System Preferences > Sharing and turn on at least File Sharing and Remote Login. With everything set, you can now remotely log in to your home computer using iCloud's network wherever you have internet access.

To start with, you need to do is find your Back to My Mac account number. In Terminal (Applications > Utilities), type:

dns-sd -E

The final nine digit ...

Flush DNS cache in Lion and Mountain Lion

Wed, 08 Aug 2012 07:30:00 -0700

I came across this Apple technical note this morning, which describes how to flush the DNS cache on your Mac. We have a hint for 10.5, which is also valid for 10.6, but we're not up to date.

So, as a reminder, to flush the DNS cache in Mac OS X 10.5 and 10.6, run this command in Terminal:

sudo dscacheutil -flushcache

To do the same in 10.7 and 10.8, run this command:

sudo killall -HUP mDNSResponder

As Apple points out, you might need to do this in the following situation:

"OS X keeps a local cache of resolved DNS queries for a time defined by the DNS server, but sometimes it may be necessary to reset the cache immediately and re-query a DNS server. For example, you might do this after an entry on the server is changed or a new entry is added."

Clear out phantom NFS shares

Mon, 23 Jul 2012 07:30:00 -0700

This is a hint about phantom NFS shares that may linger on your system long after you stopped accessing the share, and that may cause slowdowns and errors with various disk utilities. The information here applies to Lion, and may differ in earlier and later versions.

I used to have a NAS device that I named "dns323," and which was visible in the Finder as an NFS share. (The unit used a Linux-formatted disk.) In the past few months, whenever I used the excellent Yasu system maintenance utility, it would report an error message, saying that the file "dns323" wasn't found. I eventually realized that this problem started when I stopped using that NAS device. I also noticed that Find Any File was starting very slowly; and when I used Find Any File to see if it could find any trace of "dns323," it listed the file in its results list, but said that the item had disappeared.

I eventually realized that there was a directory named "dns323" in my user folder, but that dire ...

Airport Utility 6.0

Tue, 07 Feb 2012 07:30:00 -0800

Airport Utility 6.0 was released a few days ago.

You may want to keep both 5.6 and 6.0 versions. I used Pacifist, and manually reinstalled the 5.6 version side by side. Lots of missing features in the new utility. No way to tweak wireless options for Mode, Frequency, Multicast Rate or Transmit Power, and such a tiny window for port mapping list. An elegant interface, but at a price.

For a thorough review and pointers to stand alone updates, read here.

[crarko adds: Consider this a public service announcement. It also appears that AirPort Utility 6.0 only functions with the 802.11(n) compatible base stations, so that old AirPort Express you may have (like I do) is not supported. I've actually saved many older versions of the utility, even for the original Graphite (flying saucer) bases.]

Fix dropout problems when streaming music over Airport Express g

Tue, 10 Jan 2012 07:30:00 -0800

I've been using Airport Express wireless-g for years to stream music to my stereos. And they work great once you get them working, but with the wireless-g models, I have always had problems setting them up on a new network after they have already been setup on another network. I use it as a streaming device, so it is set up as a device on my network, and not as my router. The problem with dropouts when streaming music over an Airport Express g can be resolved by changing the network settings on the wireless router.

First of all, the Airport Utility never seems able to find an Airport Express that does not have factory settings and is not set to communicate with the existing wireless network. Sometimes holding down the reset button on the AE until the light blinks rapidly while it is plugged in works. In other cases, I have had to hold it down before plugging it in and then plug it in to get it to work. I have often had to repeat these steps multiple times before I can get ...

10.7: Mount AFP volume with root bug

Mon, 09 Jan 2012 07:30:00 -0800

I'm sick of waiting for Apple to come up with a fix to trying to mount a volume in 10.7 while logged in as root so I came up with my own solution.

cat >/tmp/mountVolume.sh <<-"EOF"
osascript -e 'mount volume "afp://username:password@server/path/"'
EOF
chmod 755 /tmp/mountVolume.sh
su -l guest /tmp/mountVolume.sh
rm -f /tmp/mountVolume.sh

When run as root this will use the guest account to mount the volume -- it's a work around and only recommended for those whom understand the root account.

[crarko adds: I haven't tested this one.]

10.7: Slowdown with a new MobileMe/iCloud Password

Fri, 30 Dec 2011 07:30:00 -0800

My Mac started working extremely slowly and I couldn't understand the reason for a while.

I knew my wireless was working seemingly without problems (iPad and iPhone working normally) but I thought to run the AirPort Utility to check out the wireless network.

My AirPort Extreme was reporting a problem. It turns out that I had changed my password on MobileMe to match iCloud, and of course my AirPort Extreme did not know that. It was trying to connect to the MobileMe servers with no success. I guess it was trying to connect to MobileMe non-stop and it was slowing down my system significantly. Fixing the password within the AirPort Extreme resolved the issue.

[crarko adds: It's always worth looking at network related issues when an unexpected slowdown happens. And when a transition happens (like the Mobile Me -> iCloud migration) expect to see issues like this happen. Fortunately they're easy to correct once identified.]

Getting port mappings and DHCP usage from an Airport Device

Thu, 29 Dec 2011 07:30:00 -0800

If you're like me, I'm frustrated by the way the Airport Utility displays NAT port mappings and DHCP assignments. I have a lot of ports mapped, and quite a few devices on my network and it's painful to remember which ports are mapped to which devices. I've searched high and low to find something to help and come up blank.

I wrote the following bash script which relies on the built-in utility PListBuddy to extract the relevant values from the property list that can be exported from the Airport Utility. To use it, open Airport Utility and select the device that has the mappings.

Press the 'Manual Setup' button (or Cmd+L) and the Utility will load the information from the device. Next choose Export Configuration File... from the file menu and save it to disk. Now run the bash script below and it will extract the values and send them to stdout in tab delimited form. You can then open the result in a spreadsheet or editor of your choice and see all your port mappings, ...

10.7: Hidden Mobile Network Profile support

Fri, 28 Oct 2011 07:30:00 -0700

Opening a .mobileconfig file in Lion exposes an otherwise hidden System Preference, 'Profiles' as shown here.

The .mobilconfig files are typically used to manage network settings on iOS, including the Access Point Name (APN).

To view this in Lion, just open a .mobileconfig file from Finder and System Preferences will now reveal 'Profiles' with a means to manage multiple profiles.

If you install a .mobileconfig, Profiles will remain available in System Preferences; if you delete all profiles, then Profiles no longer appears in System Preferences.

This doesn't yet seem to affect network access or browsing at all, so it is possible this feature exists to pave the way for more unified management of APN on desktops with mobi ...

10.7: Manage firewall logs

Wed, 05 Oct 2011 07:30:00 -0700

After upgrading to 10.7 my firewall logs were filled with endless "Firewall: Allow foo connecting from 1.2.3.4:1234 to port 1234 proto=x". Happily the logging system can be told to selectively ignore these messages.

Certain applications use lots of incoming network connections, and the default behaviour in Lion when the firewall is enabled is to log every single allowed connection.

A single rule line in /etc/asl.conf can silence these useless messages.

? [= Sender Firewall] [A= Message Allow foo] ignore

You can add this line using your favorite text editor, but you'll need one that can save files with root-level permissions (like the non-App Store version of TextWrangler).

[crarko adds: I haven't tested this one. To be honest, I don't run the OS X firewall.]

MCX Refresh for Mobile Accounts

Thu, 22 Sep 2011 07:30:00 -0700

I needed to forcibly refresh the per user mcx for a large number of mobile users across many desktop machines under Snow Leopard so I wrote this short script that will do just that.

Can be run from remote desktop (as root), or locally (sudo). It will not always successfully refresh the mcx, but it will force it to be reloaded from the server on the next logon.

Here's the shell script:

#Brutally refresh mcx for a machine and all mobile accounts on it

#Clear machine cache
dscl . -list Computers | grep -v "^localhost$" | while read computer_name ; do sudo dscl . -delete Computers/"$computer_name" ; done
echo "Cleared machine MCX cache."
#Get a list of locally cached accounts
for usr in `dscl . -list /Users AuthenticationAuthority | grep LocalCachedUser | awk '{print $1}' | tr  ...

Annotate information in Connect to Server dialog

Wed, 21 Sep 2011 07:30:00 -0700

In Finder, Command+K (Finder » Go » Connect to Server�) permits the storing of frequently used server addresses and protocols. However, when servers are indicated only by their IPv4 or IPv6 addresses, it is not easy to remember which address corresponds with which server. There appears to be no way to include text information associated with server addresses.

It is possible to include the # anchor at the end of the address and to indicate some information after this #. No spaces are allowed after the #.

Examples:

vnc://fkm@[2b01:0670:3201:1137:0211:24ff:ffe0:4bc6]#eMac_Conservation
afp://mgi@[2a01:0e35:2d49:0580:9227:e2ff:fef2:29ff]#Macbook_d_Emelyne
smb://129.172.107.192#DataXlab

Note that the true addresses have been changed of course in the examples.

[crarko adds: This works at least as far back as Leopard, and it wouldn't surprise me if it goes back further. I didn't find an obvious duplic ...

10.7: Enable AirDrop on Macs without supported wireless hardware

Fri, 16 Sep 2011 07:30:00 -0700

AirDrop is a handy way to share files between Macs. Unfortunately, it is only supported on newer models which have the hardware necessary to support a certain type of point-to-point WiFi connection. There is, however, a hidden setting to enable AirDrop on older Macs. Just type:

defaults write com.apple.NetworkBrowser BrowseAllInterfaces 1

into a Terminal window, hit enter, and relaunch the Finder.

Note that:

You must do this on both the sending and receiving macs, even if one of them already has the correct WiFi hardware (I think).
You will be able to see other macs on the same network, and they will be able to see your Mac (when AirDrop is open), even if they are not physically nearby. On a larger network with many Macs, this could potentially cause some confusion, although it shouldn't be a real security issue. This may be why Apple decided not to enable this feature by default.
Both macs must be connected to th ...

10.7: Monitor your Wi-Fi with Wi-Fi Diagnostics

Wed, 24 Aug 2011 07:30:00 -0700

Lion ships with an app called Wi-Fi diagnostics. It allows you to monitor Wi-Fi networks your computer is connected to and collect various kinds of information. This utility could be very useful for finding problems or doing research on your Wi-Fi networks.

The easiest way to launch Wi-Fi Diagnostics is to open it directly from the location /System/Library/CoreServices.

Once it launches, you get some options to choose from. As an example, let's use the first, Monitor Performance. Select that and click Continue.

You are given a live-updating graph of the signal/noise ratio of your network. This could be useful for live testing to find problems with interference. For example, turn on your coordless phone and see if your ratio worsens. If it does, move your router farther away from the phone.

The other options are also useful, allowing you to log events like people connecting and disconnecting, and allowing you to sample raw data sent acros ...

10.7: Active Directory Binding

Tue, 23 Aug 2011 07:30:00 -0700

Many people, myself included seem to be having problems binding 10.7 machines into Active Directory, a cryptic 'Error 5202' seems to be fairly common. Here's the fix that worked on our network.

Initially I managed to get machines to bind by manually creating an edu.mit.Kerberos file and populating it before performing the actual bind. This would work but a reboot would often cause a 'Network Accounts Unavailable' message.

The opendirectoryd logs were full of messages such as 'No preferred destination' and 'Failed to retrieve keychain password for 'MACHINENAME$' module '' node '/Active Directory/DOMAIN'.'

On a whim I tried disabling IPv6 on the ethernet adapter -- which is apparently no longer possible using the GUI in 10.7. Once I disabled it from the command line the machine bound without the need to create a kerberos file and authentication worked perfectly.

You can disable IPv6 from the command line with:

networksetup -set ...

10.7: Accessing Windows shares if files/folders do not appear in Finder

Thu, 28 Jul 2011 07:30:00 -0700

I'm experiencing a problem whereby the Windows shares I use at work mount in the Finder but don't reveal 'child of child' directories. So basically I can't see any of my working files/folders.

Here's a workaround I used in this situation:

Open Terminal, navigate to the share (once mounted) in /Volumes. Navigate to one of the child of child folders (they appear in Terminal but were empty when viewed in the Finder) and type 'open.'

This opens the folder in the Finder revealing the files/folders that were invisible before. In addition, you can now navigate 'up' in the Finder to see the previously hidden parent directory.

[crarko adds: I haven't tested this one.]