macosxhints.com network tips

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.]

A cross-platform text Clipboard using Dropbox

Thu, 30 Jun 2011 07:30:00 -0700

This hint describes how to set up a cross-platform text-only clipboard using Dropbox.

I've found myself frequently having a piece of text in one computer and wanting to have it in another one. I use Dropbox all the time, so the 'easiest' was to save the text to a text file in the Dropbox folder and open it in the other computer. Hey, it's like a Dropbox Clipboard!

See, the thing I haven't mentioned is that the two machines in question are a MacBook and a Windows 7 box, so that leaves out any Mac- or Windows-only solution. I also want something simple (so Synergy is out too) and tweakable. Full clipboard support is not simple, but fortunately I just need plain text and AppleScript (for OS X) and AutoHotkey (for Windows) can do everything I'll need, so let's code a bit.

One of AutoHotkey's strengths is its complete keyboard control so it can do it all in one punch: ...

Toggle Airport On and Off

Tue, 24 May 2011 07:30:00 -0700

The hint 'Control Airport Without Menu Bar' in the June issue of Macworld (also see this article) was very informative and useful. I devised a simple script based on the article hint that toggles airport on and off.

Here is the script. Copy and Paste it into AppleScript Editor and save it as an Application.

--
-- Toggle Airport Power On and Off
--
if (offset of "On" in (do shell script "networksetup -getairportpower en1")) > 0 then
	do shell script "networksetup -setairportpower en1 off"
else
	do shell script "networksetup -setairportpower en1 on"
end if

[crarko adds: I tested this, and it works as described. It follows precisely the method described in the linked Macworld article, in c ...

Not a hint, but a funny networking Easter egg

Thu, 12 May 2011 07:30:00 -0700

Not really a hint but I thought this was hilarious.

I did a Get Info on one of the PC Servers connected to my Mac when I noticed the contents of the icon on the preview area. Yes, it is a picture of the Blue Screen of Death. All the connected PC servers get this icon. Cannot tell what version of Windows BSOD this is though.

Open a Finder window.
Right click on a server (under 'Shared' in the Sidebar).
Select Get Info.

I love the extra attention Apple gives to details in OS X.

[crarko adds: Another reader (titaniumtroop) set in a similar submission about the Quick Look icon for a Windows Server being the BSOD. Apple has removed so many of the good old Easter eggs it's nice to see an indication that a sense of humor still thrives in Cupertino.]

10.6: Slow SMB browsing of Windows Servers fixed

Wed, 04 May 2011 07:30:00 -0700

By default in Mac OS X browsing to Windows 2008 and 2003 Servers is extremely slow, navigating from one directory level to the next can take a minute or longer. I utilize my Mac to access the office Windows 2008 and 2003 file servers and the speed to access these shares makes it almost impossible to work from a Mac.

To make things even worse I do most of my work through a Cisco SSL VPN loaded on my Mac from home over a broadband connection. Out of pure frustration I started playing with settings in my SMB configuration and have found a way in Mac OS 10.6.7 to speed the process up drastically to where navigating folders is almost instantaneous (including over my VPN). This makes the Mac work just as fast as my Windows 7 workstation when connecting to Windows servers.

In order to fix the slow SMB browsing you will need to edit the smb.conf fi ...

Several networked and non-networked options for Time Machine backups

Fri, 08 Apr 2011 07:30:00 -0700

This hint collects together what I have learned about solutions for Time Machine backups. There are a number of viable solutions, and I cover several of them.

External USB or Firewire drive

The most basic solution is a directly-attached external USB drive enclosure. This might be okay for desktop machines, but what bothers me about this is that both the Mac and the drive are on the same power circuit. If lighting strikes, then both can get hit at the same time. In a Mac Pro, you can use another internal drive for TM. And there are also external RAID solutions like I mention below. Unless you are particularly disciplined, this is a lousy solution for portable Macs. When I was going this route, I was lucky if I remembered to plug in the backup drive once a week. Maybe other people can do better than that, but it's still inconvenient.

Thus, I prefer networked solutions. However, at the end of this hint, I go into a discussion on why TM is a great des ...

Keep attempting reconnection to wireless network

Thu, 24 Feb 2011 07:30:00 -0800

Having trouble automatically reconnecting your unattended Mac to a wireless network because of unreliable signal quality? If you would like to have it keep reattempting reconnection until it manages to connect it's fairly simple to setup.

You need to use the airport command line tool in the Terminal. Open a terminal and run the following command (with no line breaks), typing in your password when prompted:

sudo /System/Library/PrivateFrameworks/Apple80211.framework/Versions/Current/Resources/airport prefs joinmode=automatic joinmodefallback=keeplooking

Unlike the JoinModeFallback setting of 'prompt' (which can be set in System Preferences) or 'donothing,' if it fails to join a network it will wait about a minute and then scan for a network to join again. It will do ...

Simulate Airport Express network audio

Wed, 23 Feb 2011 07:30:00 -0800

Have you ever wanted to wirelessly stream all audio from your Mac to the Unix/Windows/Mac box in your cupboard connected to your beefy stereo? Here is an alternative to buying an Airport Express for the purpose.

This tip is similar to this hint but after experimenting with that technique and various other options I think I've hit on an improved setup. Steps to perform on your Mac:

Download and install Soundflower. This will allow you to redirect all audio played on your Mac over the network.
Install MacPorts as well; this will make it easy to install esound and ffmpeg which are needed later.
Install esound with the command sudo port install esound in Terminal.
Similarly install ffmpeg with sudo port install ffmpeg.
In Syst ...

Stop Finder from rounding file sizes on Samba shares

Thu, 10 Feb 2011 07:30:00 -0800

If you have a Linux or BSD machine running Samba you may notice that its exported shares round up all files under a megabyte (i.e. 720kB becomes 1MB) by Finder.

To fix this problem add the following line to the server's smb.conf:

allocation roundup size = 0

Restart the Samba daemon, reconnect to the share, and files under one megabyte should now be calculated correctly in Finder.

[crarko adds: I haven't tested this one. I would assume (but don't know) that this change may also be needed to the Samba server on a Mac.

On most systems this file is located at /etc/samba/smb.conf or /usr/local/samba/lib/smb.conf. In Snow Leopard the location is /etc/smb.conf. You may want to save off a backup copy of the file prior to editing it. To save it you need an editor that can authenticate as root, such as TextWrangler or BBedit or you can use a command line editor invoked with sudo.]