Practical way to tackle WiFi dropout and slow performance issue in OS X El Capitan

There is a couple of occasions that I need to do have an upgrade on Mac OS X. Chances are I completely forget those tweaking tips and hope things will be resolved in next version. Something like WiFi connection tweaking I can remind from the forum. An explanation can help me remind those things I should do every single time when I need to do an OS X upgrade.

We can find all kinds of topics regarding WiFi dropout issue on OS X and someone may suggest standard procedure to get around this. For WiFi settings, Apple would like to stick to standard MTU size at 1500 bytes for Ethernet network. But, why?

With WiFi connection, we can do a ping test like this:

$
$
$ ping -D -s 1500 google.com
PING google.com (203.5.76.246): 1500 data bytes
ping: sendto: Message too long
ping: sendto: Message too long

Note:
Option -D suppresses fragmentation for the packet (force to transmit whole packet at a time)
Option -s 1500 specify the packet size, i.e., 1500 bytes

Problem is there is an overhead added on top of packet size for every transmission. That is why we get 'Message too long' responses from there.

To rectify this problem, let's do the math:

Optimum MTU size = Packet size + Overhead

What about the overhead? The overhead would be 28 bytes because 20 bytes are reserved for the IP header and 8 bytes must be allocated for the ICMP Echo Request header.

So, maximum packet size permitted in each network packet is actually:

Optimum MTU size = Non-fragmented Packet size +  28 bytes

Here we say MTU size will theoretically be 1500. Packet size allowed would be

(1500 -28)=1472 bytes

But, is it practical? Let's test this.

To test this magic number, issue the following command in Terminal:

$
$
$ ping -D -s 1472 google.com
PING google.com (203.5.76.246): 1472 data bytes
1480 bytes from 203.5.76.246: icmp_seq=0 ttl=56 time=7.787 ms
1480 bytes from 203.5.76.246: icmp_seq=1 ttl=56 time=4.838 ms
1480 bytes from 203.5.76.246: icmp_seq=2 ttl=56 time=4.360 ms
1480 bytes from 203.5.76.246: icmp_seq=3 ttl=56 time=6.184 ms

Packets are now transmitted successfully with this payload (1472). Therefore, we can be sure the optimum MTU payload size would be 1500 (luckily a theoretical value this time) just for this particular WiFi network.

With no fragmentation happening, each packet should be theoretically transmitted as a whole and not broken in parts. This can improve the network speed effectively in an ideal signal condition.

Just remind that the size of payload can be different across various locations and wireless routers. You might need to find the smallest optimum payload which sits within the size range of successful transmission for most networks you'll be connecting, either at home or office. Try stepping down the value until you find transmission works for all the networks you have tried.

Apply this payload value in Network settings panel and hopefully it'll help reduce the number of WiFi dropout and improve the WiFi network speed.

Fix Hombrew problems after upgrading Mac OS X from Mavericks to El Capitan, skipping Yosemite

I have been sticking with Mavericks (OS X 10.9.x) since released and now skip Yosemite and directly upgrade to the solid build of El Capitan (OS X 10.11). It's just a direct upgrade and things seem to be working after a couple of reboots.

Well, we all know installed packages may not work at all. For instance, Developer tools like Homebrew seems broken again.

As seen on the Github, people have started collaborating with each others to resolve this.

https://github.com/Homebrew/homebrew/issues/40519

First thing to fix broken Homebrew directory is the permission issue. Error like this for brew update command:

xcrun: error: invalid active developer path (/Library/Developer/CommandLineTools), missing xcrun at: /Library/Developer/CommandLineTools/usr/bin/xcrun
xcrun: error: invalid active developer path (/Library/Developer/CommandLineTools), missing xcrun at: /Library/Developer/CommandLineTools/usr/bin/xcrun
Stashing your changes:
xcrun: error: invalid active developer path (/Library/Developer/CommandLineTools), missing xcrun at: /Library/Developer/CommandLineTools/usr/bin/xcrun
xcrun: error: invalid active developer path (/Library/Developer/CommandLineTools), missing xcrun at: /Library/Developer/CommandLineTools/usr/bin/xcrun
Error: Failure while executing: git stash save --include-untracked --quiet

So, try the following command first:

sudo chown $(whoami):admin /usr/local && sudo chown -R $(whoami):admin /usr/local

Second trial of brew update, another error appeared while doing brew update as follows:

Error: Failure while executing: git pull -q origin refs/heads/master:refs/remotes/origin/master.

Since major upgrade, we need to install recent release of Xcode Command Line Tools. An easy way is to install Xcode 7.0.1 from AppStore and then open Xcode to agree the terms and conditions.

Within CXcode, click menu item:

[Xcode]->[Open Developer Tool]-> [More Developer Tools...]

It helps to open Apple's download website for Developer Tools.

Click to download and install the following package :

Command Line Tools OS X 10.10 for Xcode 7

Reopen Terminal again and then try brew update, once again another error message shows up. But this time it looks like things get fixed by the second call of brew update command. So, issue the update command twice to get itself fixed and ready:

$brew update
#Error message...
$brew update
#It works this time...

Ultimate Guide on TP-LINK Archer C2 AC750 Wireless Dual Band Gigabit Router - USB Printer sharing on OS X

This guideline should be applying to any USB compatible printer for sharing on OS X over the USB port of TP-LINK Archer C2 Wireless Router.

The best thing of this router is that it's NBN ready and has both WAN/LAN ports supporting up to 1000Mbps which is abundant for movie streaming and VOIP communications within local network and a possible extension to future upgrade of NBN services. As for 802.11ac standard, this router does the right job for 5GHz Wi-fi transfer which is up to 433Mbps. It's also backward compatible with 802.11b/g/n. The cost is average but you might feel good about having an 802.11ac compliant router with this price tag. Compared with my old 802.11n router, it really makes a difference in terms of the speed and stability. One benefit is beamforming if you are using newer Macbook with antenna supporting 802.11ac standard.

Ref: http://www.tp-link.com.au/products/details/cat-9_Archer-C2.html

However, the firmware and software support is limited for this brand. Yet, it's still possible to find have a software upgrade to make things working.

First thing first, upgrade the firmware to the latest stable version via here:

Ref: http://www.tp-link.com.au/download/Archer-C2.html#Firmware

High-end product like Archer C7 is based on the same architecture as C2 so their technical support recommended using newer version of software available for Archer C7 instead.

Ref: http://www.tp-link.com.au/products/details/cat-9_Archer-C7.html

The key to bridge up the USB printer connected to the router is the software called:

TP-LINK USB Printer Controller

It's better to use the package from a recent release of newer product line like Archer C7:

Try downloading the installation package 

Archer C7_V2_USB_Printer_Controller_Installer_Mac 

from here:

http://www.tp-link.com.au/download/Archer-C7.html#Utility 

Extract it and find the .DMG file to install on Mac OS X:

TP-LINK_USB_Printer_Controller_Installer_Mac.dmg

A system reboot is required.

Before opening the printer controller software, it is necessary to have USB printer plugged into your Mac computer first and finish an initial setup based on USB connection. Assuming you have the printer driver for your USB printer, it's an easy but important step to setup a local printer profiler on your Mac.

Once it's successful on setting up your print via local USB connection, you should have a available local printer in "Printers and Scanner" Control Panel. 

Now you can proceed to plug the USB printer into the USB port of TP-LINK Wireless Router for remote setup.

The software TP-LINK USB Printer Controller will let you to bridge up the remote printer to your local USB printer profile. It may show offline at first but will turn into online mode after the first remote printing is done successfully.

Assuming you are connecting to the Wi-Fi network from TP-Link Wireless Router, you need to open up TP-LINK USB Printer Controller interface. 

Under the Router's name, you should find the USB printer device (whether it's UNKNOWN or exactly the printer model name) already connected to the router. 

Click on the printer device and click on Auto menu button and then "+Set Auto-Connect Printer" button to find the installed printer list of available local printer profiles on you Mac. 

Select the target printer profile and click Apply button to link up the remote printer and you're done.

Remember to keep TP-LINK USB Printer Controller Window opening during remote printing process. Now, you can have a try to print out anything you like with your local printer profile on your Mac and the print job will be redirected to the shared printer on the wireless router.

Install Perl HL7 Toolkit on XAMPP OS X Mavericks

Perl version HL7 Toolkit is in its alpha stage but offers general support to HL7 V.2 messaging.

The Perl HL7 toolkit consists of:

Net::HL7, a lightweight Perl API for parsing, formatting, manipulating, sending and receiving HL7 messages,
hl7d, an implementation of a forking HL7 server for inbound interfaces, and
hl7qd, an HL7 queue daemon for outbound interfaces.

For basic testing, we'll need Perl module like Net::HL7 installed properly and a running HL7 server like hl7d daemon.

OS X Mavericks comes with its own version of Perl which is suitable for running scripts for system administration whereas most users should avoid touching it for development.

Alternatively, users can install their favourite version of Perl to run the scripts with specific modules installed on the system.

For web development, bundled package like XAMPP is accompanied with latest version of Perl which collaborates with Apache module mod_perl to delivery services to Internet users.

With CPAN already installed under XAMPP folder, it's easy to install the toolkit.

For the very first time using of CPAN under XAMPP by simply typing

$ /Applications/XAMPP/xamppfiles/bin/cpan

in Terminal Window, you'll be asked questions to setup the environment and you can almost give default answer to every single question of this. Once done, you're ready to install Perl module to support HL7 within XAMPP.

To run HL7 toolkit, you'll need Perl module Net::HL7:

$ /Applications/XAMPP/xamppfiles/bin/cpan install Net::HL7

Before all these, just need to make sure the version of Perl running as default to be in the path of XAMPP installation, i.e., /Applications/XAMPP/xamppfiles/bin/

For sure, please run a test like this:

$ which perl
/Applications/XAMPP/xamppfiles/bin/perl

Please notice that most Perl scripts may start with the beginning statement like this:

#!/usr/bin/perl

This actually points to the default installation of Perl whereas desired Perl modules like Net::HL7 might not exist at all.

To test whether your version of Perl has desired module installed, please try this command:

$ perl -e 'use XXXX::xxxx;'

If the specific module is not installed, general error message would be like this even after installing your favourite Perl module with CPAN:

Can't locate XXXX/xxxx.pm in @INC contains: ...

So, basically, you should not run Perl script by just typing ./?????.pl in Terminal. Instead, using full path of Perl to call the script:

$ /Applications/XAMPP/xamppfiles/bin/perl ./?????.pl

This ensure that your desired version of Perl is used to run the script.

To install hl7d server, you may download the package to local drive via this link:
http://hl7toolkit.sourceforge.net/#hl7d

Unzip the *.tar.gz file to extract a folder with source code for building:

$ tar -xzf hl7d-(version).tgz

And then start installation in good old fashion style:

$ cd hl7d-
$ perl Makefile.PL PREFIX=
$ make
$ make test (none yet, but read the output!)
$ make install

You can also copy sample scripts to hl7d's installation directory.

$ cp t/* /usr/local/hl7d-(version)/t/

For Perl version of hl7d server, there is a little change to make it running successfully under OS X environment.

After the installation of hl7d, please change the line for LocalPort setting in hl7d.pl as follow:

# establish SERVER socket, bind and listen.
#
my $server = new Net::HL7::Daemon
    (
  #LocalPort => $cfg{PORT},
         LocalPort => 12002,
         Listen    => $cfg{LISTEN}
     );
$server or die "Couldn't create daemon";

This makes sure hl7d daemon starts properly at port 12002.

To start hl7d server in debug mode, please type in the command:

$ /usr/local/hl7d-/hl7d.pl --nodetach --debug

And then you can try sample client Perl scripts within /usr/local/hl7d-/t/ subfolder in another Terminal Window. When succeeded, you will receive messages from the Terminal which hl7d server is running.

For PHP web application in XAMPP, you must install another module Net_Socket first:

$ /Applications/XAMPP/xamppfiles/bin/pear install Net_Socket

To test out PHP script running within XAMPP web application, you can create test.php file:

<?php
require_once "Net/HL7/Segments/MSH.php";
require_once "Net/HL7/Message.php";
require_once "Net/HL7/Connection.php";
require_once 'Net/Socket.php';

$msg  = new Net_HL7_Message();
$msg->addSegment(new Net_HL7_Segments_MSH());

$seg1 = new Net_HL7_Segment("PID");

$seg1->setField(3, "XXX");

$msg->addSegment($seg1);

echo "
Trying to connect
";
$socket = new Net_Socket();
$success = $socket->connect("localhost", 12002);

if ($success instanceof PEAR_Error) {
    echo "
Error: {$success->getMessage()}
";
    exit(-1);
}

$conn = new Net_HL7_Connection($socket);

echo "
Sending message\n" . $msg->toString(true) . "
";

$resp = $conn->send($msg);

$resp || exit(-1);

echo "
Received answer\n" . $resp->toString(true) . "
";

$conn->close();
?>

Installing Composer on OS X Mavericks with XAMPP for Mac installed

Composer is a popular tool for the dependency management in PHP. It lets you declare dependent libraries for each particular project.

Let's have a quick look on what have installed so far on the development machine:

OS X Mavericks
XAMPP for Mac installed and configured properly (A running instance)
Hombrew installed and configured (Try brew doctor to tackle any problem before you start)

Steps as follows:

Assuming default installation path of XAMPP for Mac package installed as usual, please change into the directory where PHP executable resides:

$ cd /Applications/XAMPP/bin/

Check the version of PHP:

$ php --version
PHP 5.4.30 (cli) (built: Jul 29 2014 23:43:29) 
Copyright (c) 1997-2014 The PHP Group
Zend Engine v2.4.0, Copyright (c) 1998-2014 Zend Technologies

Now we know PHP version is 5.4. Let's remember this for use in next couple of steps.

If you try to install Composer with brew command now, you may end up with an error like this:

composer: Missing PHP53, PHP54, PHP55 or PHP56 from homebrew-php. Please install one of them before continuing

Error: An unsatisfied requirement failed this build.

The likely cause is that we are using PHP within XAMPP package whereas brew cannot detect its presence without installing its own PHP engine.

Supposing XAMPP package is installed properly, we can simply add the path /Applications/XAMPP/bin/ to $PATH environment variable to the end of the file ~/.bash_profile . If it doesn't work then another to get around this would be installing a new version of PHP package using brew command.

[OPTIONAL] So which version of brew's PHP engine to install? It's better match the version of PHP within XAMPP, i.e., 5.5.

[OPTIONAL] Let's install PHP54 package by using brew command:

$ brew install php55

Once finished, start installing Composer with brew commands like these:

$brew update;brew tap homebrew/dupes;brew tap homebrew/php;brew install composer

It includes the actions of updating and tapping the right repository for downloading Composer's source.

When brew's package for Composer is installed successfully, we can carry out next step to create composer.phar file within XAMPP's bin directory.

$ sudo php -r "eval('?>'.file_get_contents('https://getcomposer.org/installer'));"

We must execute the command as root privilege to avoid permission denied error.

When done, we can try composer command within /Applications/XAMPP/bin/ directory.

$ php composer.phar
   ______
  / ____/___  ____ ___  ____  ____  ________  _____
 / /   / __ \/ __ `__ \/ __ \/ __ \/ ___/ _ \/ ___/
/ /___/ /_/ / / / / / / /_/ / /_/ (__  )  __/ /
\____/\____/_/ /_/ /_/ .___/\____/____/\___/_/
                    /_/
Composer version 1e4229e22aefe50582734964d027fc1bfec16b1d 2014-10-02 11:34:17

Usage:
  [options] command [arguments]...

Then it should be ready for us to checkout new dependent packages within a new or existing PHP project directory.

Setup MySQL ODBC Driver for XAMPP on OS X Mavericks

This article is mainly for the setup of MySQL ODBC connection used in Apache server in OS X Mavericks. Of course, you can try it on OS X Lion or Mountain Lion as well.

Since Mac OS X 10.9 has been released, I have been searching for the way to revive the nearly forgotten feature of ODBC connection. As OS X is based on UNIX system, unixODBC is the first thing in mind for bridging the gap between various database products and the Mac world. Unfortunately, it is still too early to have a piece of working copy available for OS X 10.9.

As I don't remember wrong, it's a painful experience to implement a working ODBC setup on OS X platform. It's crucial to choose the right product among various combination of 32 bit and 64 bit drivers available yet we don't know which one will be working on the newest platform.

Here's the quick receipt which should work on OS X Mavericks:

Assuming we are using a lazy bundle of XAMPP for OS X package which in theory contains Apache (32 bit) and MySQL (32 bit). Since OS X is 64 bit platform which is able to run 32 bit applications, it is still safe to download a copy of 32 bit ODBC driver for use.

A recent version of MySQL connector ODBC should do the job. As of writing, it's version 5.3.2.
http://dev.mysql.com/get/Downloads/Connector-ODBC/5.3/mysql-connector-odbc-5.3.2-osx10.7-x86-32bit.dmg

OS X 10.9 doesn't provide ODBC Administrator in Utilities anymore. For GUI configuration, I go for the solution of ODBC manager:
http://odbcmanager.net/downloads/ODBC_Manager.dmg

Once we finish both of the software installations, we can start digging with Terminal commands.

In Terminal, we can can have a quick access to where ODBC configuration files are hiding under the tree of Filesystem.

The ODBC files should be located as follows:

System wide configurations:
/Libaray/ODBC/odbc.ini
/Libaray/ODBC/odbcinst.ini

These files are supposed to be empty or kept in basic information. They need further modification to get our ODBC connection working.
 Unfortunately, MySQL Connector has default installation of configuration files in user specific folder. It also creates two sample ODBC connections at the beginning of installation.

User specific configurations:
~/Libaray/ODBC/odbc.ini
~/Libaray/ODBC/odbcinst.ini

Now, we need to migrate the settings from user specific location to system wide location.

Two simple steps to get the job done:

Cut the content from ~/Libaray/ODBC/odbc.ini and paste it into /Libaray/ODBC/odbc.ini.

Cut the content from ~/Libaray/ODBC/odbcinst.ini and paste it into /Libaray/ODBC/odbcinst.ini.

Of course, you need to merge the content for the files so they contain unique section for each.

Remember to save the empty content back in ~/Library/ODBC/odbc.ini and ~/Library/ODBC/odbcinst.ini in order to eliminate any duplicate entries to be shown on ODBC Manager.

Open ODBC Manager and have a look if MySQL ODBC 5.3 ANSI Driver exist. We'll make use of this driver to create System DSN for

 Click Add... button in System DSN Tab and add the basic connection parameters:

For Apache's ODBC configuration, please have a look at here for more information:
http://httpd.apache.org/docs/2.4/mod/mod_dbd.html

It takes a little bit longer period of time to get MySQL ODBC drivers ready for mod_dbd since OS X 10.8. Now it's working.

To get rid of Firewall warning for particular application in Mac OS X Mavericks

Each time we open up an application which attempts to open a network connection in OS X, a firewall warning will always pop-up (in case you don't turn your firwall off) to ask for action like allowing a connection to be opened.

This might be annoying when you open your favourite app and get blocked by this warning everyday. The reason would be clear when you type the following command in Terminal for a check:

$
$ codesign -dvvvv /path to/your application

You probably received a feedback like this:

/path to/your application: code object is not signed at all

Well, it explains itself properly. You favourite app have not signed with a valid certificate. A valid cerficate, whether self-signed or genuine, should let OS X Firewall bypass the restriction and let the app open up network connection without warning.

You should not do the following steps unless you are pretty sure the app works normal and doesn't trigger any malicious activities, i.e., not a malware.

To generate your self-signed certificate, you can use OS X built-in app like "Keychain Access".

• From the menu "Keychain Access", select item "Certificate Assistant" and then "Create a certificate ...".
• Type in the name of your certificate in Name field and then select "Code signing" in Certificate Type selection box and then click "Create" button to generate new self-signed certificate. 

You may have to create different certificates for different apps so you can identify each one and revoke the certificate for the app in case you don't like it.

Remember the name of the self-signed certificate you created.

To sign the app you like, there are two options:

For single executable file without framework or plugins, you can try:

$
$ codesign -f -s "name of self-signed cert" /path to/your application

For big application (like *.app) with a set of framework or plugins, you should try adding option like --deep to sign every file recursively within that application:

$
$ codesign --deep -f -s "name of self-signed cert" /path to/your application

To verify the details of code signing for this app, you can re-type a command in Terminal like this:

$
$ codesign -dvvvv /path to/your application

This time you will see those signing attributes like Identifier, Hash type, CDHash, Authority and Signed time showing up properly.

After this, you can try opening your favourite app and this time no more Firewall warning should appear.