Creating a self-signed certificate with ADT

http://help.adobe.com/en_US/air/build/WS5b3ccc516d4fbf351e63e3d118666ade46-7f74.html

You can use self-signed certificates to produce a valid AIR installation file. However, self-signed certificates only provide limited security assurances to your users. The authenticity of self-signed certificates cannot be verified. When a self-signed AIR file is installed, the publisher information is displayed to the user as Unknown. A certificate generated by ADT is valid for five years.
If you create an update for an AIR application that was signed with a self-generated certificate, you must use the same certificate to sign both the original and update AIR files. The certificates that ADT produces are always unique, even if the same parameters are used. Thus, if you want to self-sign updates with an ADT-generated certificate, preserve the original certificate in a safe location. In addition, you will be unable to produce an updated AIR file after the original ADT-generated certificate expires. (You can publish new applications with a different certificate, but not new versions of the same application.)

Important: Because of the limitations of self-signed certificates, Adobe strongly recommends using a commercial certificate issued by a reputable certification authority for signing publicly released AIR applications.

The certificate and associated private key generated by ADT are stored in a PKCS12-type keystore file. The password specified is set on the key itself, not the keystore.

Certificate generation examples

adt -certificate -cn SelfSign -ou QE -o "Example, Co" -c US 2048-RSA newcert.p12 39#wnetx3tl 
adt -certificate -cn ADigitalID 1024-RSA SigningCert.p12 39#wnetx3tl

To use these certificates to sign AIR files, you use the following signing options with the ADT -package or -prepare commands:

-storetype pkcs12 -keystore newcert.p12 -keypass 39#wnetx3tl 
-storetype pkcs12 -keystore SigningCert.p12 -keypass 39#wnetx3tl

Note: Java versions 1.5 and above do not accept high-ASCII characters in passwords used to protect PKCS12 certificate files. Use only regular ASCII characters in the password.

ADT -package command examples

Package specific application files in the current directory for a SWF-based AIR application:

adt –package -storetype pkcs12 -keystore cert.p12 myApp.air myApp.xml myApp.swf components.swc

Download older version of flex SDK

http://blogs.adobe.com/flex/files/2012/05/FlexLicense.swf

netcat/ncat server file as a web server

I will use the ncat (part of nmap) tool:

1. first create a bash file with the following contents, and save it as nchttp.sh, and chmod+x on it:

#!/bin/sh

echo "HTTP/1.1 200 OK"

mydate=`date -R`

echo "Date: $mydate"

echo "Server: Apache"

echo "Last-Modified: $mydate"

echo "Accept-Ranges: bytes"

echo "Content-Disposition: inline; filename=\"$1\"";

mysize=`stat $1 |awk '/Size/{print $2}'`

echo "Content-Length: $mysize"

echo "Keep-Alive: timeout=30, max=300"

echo "Connection: Keep-Alive"

echo "Content-Type: application/octet-stream"

echo

cat $1

2. ./nchttp.sh the-file-to-be-downloaded | ncat -l -vv 8001

3. point your brower to your http://YOURSERVERIP:8001, your file will be downloaded

Faster ssh X11 Forwarding

I use ssh daily to connect to my servers and laptops around my home office. Most of the time I'm using ssh to login and build software, so it's plain and simple command line activity. However, sometimes I need to run an X11 application on a remote machine, in which case I use X forwarding to display the remote X application on my laptop. However, this can be slow. Today I stumbled on the following incantation to speed up X11 forwarding over ssh:

ssh -c arcfour,blowfish-cbc -X -C user@remotehost

Thanks to Samat Jain for this info.

The choice of cipher is based on some performance benchmarks as noted in LaunchPad bug #54180

Source: http://smackerelofopinion.blogspot.com/2009/07/faster-ssh-x11-forwarding.html

php mail() function data flow

php mail() called /usr/sbin/sendmail, which may be a symbolic link to exit4 or sendmail.postfix or whatever sendmail "MTA" installed on your system. If you change that to your own sendmail, you can probably log all outgoing emails for debugging purpose.

Build and install python and mercurial from scratch on a system

wget http://www.python.org/ftp/python/2.5.4/Python-2.5.4.tgz
wget http://www.selenic.com/mercurial/release/mercurial-1.2.1.tar.gz
tar zxvf mercurial-1.2.1.tar.gz
tar zxvf Python-2.5.4.tgz

Configure and build Python using /opt - you could use /usr/local or similar but I preferred to keep it out of my $PATH:

cd Python-2.5.4
./configure --prefix=/opt
make
su -c "make install"

Test Python installed properly:

/opt/bin/python
Python 2.5.4 (r254:67916, Mar 25 2009, 12:16:36)
[GCC 3.2.3 20030502 (Red Hat Linux 3.2.3-56)] on linux2
Type "help", "copyright", "credits" or "license" for more information.

Build Mercurial, using your Python 2.5:

cd ../mercurial-1.2.1
su -c "make install PYTHON=/opt/bin/python PREFIX=/opt"

Test Mercurial installed properly:

/opt/bin/hg --version
Mercurial Distributed SCM (version 1.2.1)
Copyright (C) 2005-2009 Matt Mackall and others

You may wish to symlink hg from somewhere in your $PATH:

su -c "ln -s /opt/bin/hg /usr/local/bin/hg"

Obviously you'll need a C compiler and associated development tools installed. You may find that the Python configure command complains of missing libraries, such as zlib-devel which can be installed via yum if required

Source: http://blog.friedland.id.au/2009/03/installing-mercurial-on-rhelcentos-3.html

When running configure, “.infig.status: error: cannot find input file:” error was generated:

This appears to be caused by by having DOS style line endings in the configure script.
You should be able to use the dos2unix command or alternatively, the tr command:

$ tr -d "\15\32" < configure > configure.new
$ mv configure.new configure

     $ chmod +x configure

 Original Post Here

linux console get image size

On linux console, if you need to get an image size, and imagemagick is not installed, you can use the following script (save it as "getimgsize.php", chmod +x, then run it with your image file":


#!/usr/bin/php -f
<?php
if ($argc<2){
        die("Usage: getimagesize IMAGEFILE\n");
}
list($width, $height, $type, $attr) = getimagesize($argv[1]);
echo "Size is $width x $height\n";

Windows 8 and Ubuntu 12.10 dual boot issue

I recently bought a HP Envy dv4 laptop for work. It came with Windows 8, and I wanted to install Ubuntu 12.10 Server on it. Here is the problems I ran into and how they were solved:

1. Internal CDROM install did not work correctly. First I thought it was because the CDROM was broken. Later on I found out that legacy BIOS support is not enabled in the UEFI. Once Legacy support is enabled in UEFI, installing from CDROM worked fine.

2. Ubuntu 12.10 64-bit did not detect that the system is using UEFI and installed GRUB-PC(which is for the old BIOS/MBR) instead. So after installation the system booted straight into Windows 8 with no  option to boot into Linux.

3. I downloaded the Boot Repair and ran it. It uninstalled the grub-pc and installed grub-efi but at the end it stated that error occurred and suggested that I move the Linux into the first partition. This was not an easy option for me. So the system still cannot boot into Linux.

4. What saved the day was the tool called "rEFInd" found in  This Post . The actual website is located at HERE. A great piece of software with clear instructions. So I booted into Windows 8 and followed the instruction listed under "

Installing rEFInd Manually Using Windows"

5. It worked great!! Later on I used the "bcdedit" command to set the boot manager to grubx64 directly and it worked as well.

Thanks Rod!

Lenovo thinkpad technical details of different models

Thinkpad http://www.lenovo.com/psref/

How to Tell if Your CPU supports Virtulization Technology on Linux

It’s quite simple: We’ll need to take a peek inside the /proc/cpuinfo file and look at the flags section for one of two values, vmx or svm.

• vmx – (intel)
• svm – (amd)

You can use grep to quickly see if either value exists in the file by running the following command:

egrep ‘(vmx|svm)’ /proc/cpuinfo

If your system supports VT, then you’ll see vmx or svm in the list of flags. My system has two processors, so there are two separate sections:

flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm syscall nx lm constant_tsc pni monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr lahf_lm
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm syscall nx lm constant_tsc pni monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr lahf_lm

VT technology can still be disabled in your computer’s BIOS, however, so you’ll want to check there to make sure that it hasn’t been disabled. The flags in cpuinfo simply mean that your processor supports it.


Source: http://www.howtogeek.com/howto/linux/linux-tip-how-to-tell-if-your-processor-supports-vt/

vmware and virtualbox usb device in use not able to attach to VM

If you have a USB device that cannot be detached from the HOST and attach to your VM, one possible reason is because you are using USB 3.0 port the device. Change to a USB 2.0 port should help in that case. This was my case with Windows 7 running on Thinkpad T530.

Resolve IP Fragmentation, MTU, MSS, and PMTUD Issues with GRE and IPSEC

Resolve IP Fragmentation, MTU, MSS, and PMTUD Issues with GRE and IPSEC

Excerpt:

Avoiding IP Fragmentation: What TCP MSS Does and How It Works

The TCP Maximum Segment Size (MSS) defines the maximum amount of data that a host is willing to accept in a single TCP/IP datagram. This TCP/IP datagram may be fragmented at the IP layer. The MSS value is sent as a TCP header option only in TCP SYN segments. Each side of a TCP connection reports its MSS value to the other side. Contrary to popular belief, the MSS value is not negotiated between hosts. The sending host is required to limit the size of data in a single TCP segment to a value less than or equal to the MSS reported by the receiving host.
Originally, MSS meant how big a buffer (greater than or equal to 65496K) was allocated on a receiving station to be able to store the TCP data contained within a single IP datagram. MSS was the maximum segment (chunk) of data that the TCP receiver was willing to accept. This TCP segment could be as large as 64K (the maximum IP datagram size) and it could be fragmented at the IP layer in order to be transmitted across the network to the receiving host. The receiving host would reassemble the IP datagram before it handed the complete TCP segment to the TCP layer.

vboxheadless does not listen on VRDE port

vboxheadless in virtualbox is really good, but it does not report error messages very well. If you see it running but does not listen on the VRDE port, there is a chance that you have the following issue:

This supposes that your host is Linux.

Your host may have loaded the linux KVM modules, which conflicts the VirtualBox.  Do a "lsmod" to see whether you have the following modules installed:


 kvm_intel
 kvm

If you do, "rmmod" them. To make it permanent, put them in /etc/modprobe.d/blacklist.conf

debug udev rules

To debug your udev rules, just run udevd as:

udevd --debug

Keep in mind that some udevd cannot detect changes in rule files so make sure you restart udevd after rule changes.



Qt embedded Linux usb keyboard auto detect

Qt in embedded Linux can detect the plug/unplug of an USB Mouse and enable it when USB mouse is plugged in. For USB keyboard, it does not support such capability.

To solve this problem, I have to resort to qt plugin. The following links will provide all the necessary material to write and deploy a plugin.

The plugin is a dynamic library that qt app looks for when it starts. In this case, the "customized qt keyboard driver" is located at qt-binary-directory/kbddrivers/libhotplugkbplugin.so. Before start the app, set the key board environment variable:


export QWS_KEYBOARD="HotPlugKb"

The plugin is based on the simplestyle plugin below structure-wise and based on the qt internal linuxInput driver function-wise.

http://doc.qt.nokia.com/4.7-snapshot/qkbddriverplugin.html
http://qt-project.org/doc/qt-5.0/deployment-plugins.html
http://doc.qt.nokia.com/4.7-snapshot/plugins-howto.html
http://doc.qt.nokia.com/4.7-snapshot/tools-styleplugin.html
http://doc.qt.nokia.com/4.7-snapshot/qt-embedded-charinput.html

Debugging Plugins

export QT_DEBUG_PLUGINS='2'

Makefile and autoconf/automake gcc version check

Makefile:

GCC_VERSION_GE_45 := $(shell g++ -dumpversion | gawk '{print $$1>=4.5?"1":"0"}')
ifeq ($(GCC_VERSION_GE_45),1)
    AM_CXXFLAGS +=-Wunreachable-code
endif

Note the use of double $ sign inside gawk script.


In Autoconf/Automake:
1. Add the following line to configure.ac
  AM_CONDITIONAL(GCC_GE_45, test `g++ -dumpversion | gawk '{print $1>=4.5?"1":"0"}'` = 1)

2. Add the following line to Makefile.am

  include $(top_srcdir)/common.mk

3. Add the following lines to common.mk

if GCC_GE_45

    AM_CXXFLAGS +=-Wunreachable-code

endif

buffer overflow example and gcc flags

If you want to try some buffer overflow examples online, make sure you compile your C code with the gcc flag:

     -mno-accumulate-outgoing-args 

otherwise your assembly code may look different than the assembly code on the book. Read more at this Stackoverflow post

hg serve multiple projects

1. Create a file under the parent directory of the multiple project hg directories
Example:
#> cat webconf
[collections]
repos/ = .

[web]
allow_push = *
push_ssl = false

2.  hg serve --web-conf ./webconf -d

debian add key

sudo gpg --keyserver subkeys.pgp.net --recv-keys 55BE302B
sudo gpg -a --export 55BE302B | sudo apt-key add -