I needed to install a local jar file into my laptop’s local maven repository and found this article. I used this approach to install this jar file in my repo:
mvn install:install-file -Dfile=my-model-1.2.1.jar -DgroupId=com.cyberaka.my.package -DartifactId=my-model -Dversion=1.2.1 -Dpackaging=jar -DgeneratePom=true
This duly added the local jar file under appropriate group id and artifact id inside my maven repository and I was able to refer to this dependency through my project’s pom.
I needed to make SSH connection into a VM box setup inside VirtualBox which by default uses NAT. To enable this I had to setup port forwarding. This article proved useful.
I used this link to fix the error of sudo command not found on fresh install of Debian 8.
I used this link to successfully setup a Open SSH server on a Debian 8 VM.
Lets say I have two servers running on my laptop
1. http://localhost:3000 – This is the UI
2. http://localhost:4000 – This is the web services API
So now I need to setup something like this:
1. http://localhost/ – This should point to UI
2. http://localhost/api/ – This should point to web services API
To set this up I have used NGINX and added this section in the “server” section of the nginx.conf file. On my Mac system this file is located at: /usr/local/etc/nginx/nginx.conf
location /api/ {
proxy_set_header X-Forwarded-Host $host;
proxy_set_header X-Forwarded-Server $host;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_pass http://localhost:4000/;
}
location / {
proxy_set_header X-Forwarded-Host $host;
proxy_set_header X-Forwarded-Server $host;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_pass http://localhost:3000/;
}
To reload NGINX I use the “-s reload” parameter for nginx. On my Mac I execute this command:
/usr/local/Cellar/nginx/1.10.0/bin/nginx -s reload
I needed to write a small shell script which would allow me to make some decision based on user choices. I needed the user to specify Yes, No or Cancel for an operation. The following piece of hack does the job well.
#! /bin/bash
# define constants
declare -r TRUE=0
declare -r FALSE=1
user_choice() {
local str="$@"
while true
do
# Prompt user, and read command line argument
read -p "$str " answer
# Handle the input we were given
case $answer in
[yY]* ) return $TRUE;;
[nN]* ) return $FALSE;;
[cC]* ) exit;;
* ) echo "Y - Yes, N - No, C - Cancel. Please choose valid option.";;
esac
done
}
if user_choice "Execute Job 1? "; then
echo "Executing Job 1.."
fi
if user_choice "Execute Job 2? "; then
echo "Executing Job 2.."
fi
The following links were referred to achieve this little script:
http://linuxcommand.org/wss0090.php
https://bash.cyberciti.biz/guide/Returning_from_a_function
http://alvinalexander.com/linux-unix/shell-script-how-prompt-read-user-input-bash
Lets say I type something in Hindi and the outcome is listed below:
तीन व्याकितियों की औसत आयु ३३ वर्ष है.
In Hex View it will look like:
e0 a4 a4 e0 a5 80 e0 a4 a8 20 e0 a4 b5 e0 a5 8d e0 a4 af e0 a4 be e0 a4 95 e0 a4 bf e0 a4 a4 e0 a4 bf e0 a4 af e0 a5 8b e0 a4 82 20 e0 a4 95 e0 a5 80 20 e0 a4 94 e0 a4 b8 e0 a4 a4 20 e0 a4 86 e0 a4 af e0 a5 81 20 e0 a5 a9 e0 a5 a9 20 e0 a4 b5 e0 a4 b0 e0 a5 8d e0 a4 b7 20 e0 a4 b9 e0 a5 88 2e e0 a4 85 e0 a4 97 e0 a4 b0 20 e0 a4 89 e0 a4 a8 e0 a4 95 e0 a5 80 20 e0 a4 86 e0 a4 af e0 a5 81 20 e0 a5 a8 3a e0 a5 a9 3a e0 a5 aa 20 e0 a4 95 e0 a5 87 20 e0 a4 85 e0 a4 a8 e0 a5 81 e0 a4 aa e0 a4 be e0 a4 a4 20 e0 a4 ae e0 a5 87 e0 a4 82 20 e0 a4 b9 e0 a5 8b 2c e0 a4 a4 e0 a5 8b e0 a4 b9 20 e0 a4 89 e0 a4 a8 e0 a4 ae e0 a5 87 20 e0 a4 b8 e0 a5 87 20 e0 a4 b8 e0 a4 ac e0 a4 b8 e0 a5 87 20 e0 a4 ac e0 a5 9c e0 a5 87 20 e0 a4 95 e0 a5 80 20 e0 a4 86 e0 a4 af e0 a5 81 20 e0 a4 95 e0 a4 bf e0 a4 af e0 a5 8d e0 a4 a4 e0 a4 a8 e0 a5 87 20 e0 a4 b5 e0 a4 b0 e0 a5 8d e0 a4 b7 20 e0 a4 b9 e0 a5 8b e0 a4 97 e0 a5 80 3f
The main thing to notice here is that every hindi character is starting with the byte “E0”. This is basically a code point which identifies the code size of the UTF-8 character. The following table appropriate highlights it:
Binary Hex Comments
0xxxxxxx 0x00..0x7F Only byte of a 1-byte character encoding
10xxxxxx 0x80..0xBF Continuation bytes (1-3 continuation bytes)
110xxxxx 0xC0..0xDF First byte of a 2-byte character encoding
1110xxxx 0xE0..0xEF First byte of a 3-byte character encoding
11110xxx 0xF0..0xF4 First byte of a 4-byte character encoding
Reference: https://stackoverflow.com/questions/5290182/how-many-bytes-does-one-unicode-character-take/33349765#33349765
I needed to email an HTML report and I was not happy with the fact that we have to create zip file containing the HTML, Images etc. I knew it was possible to embed base64 data directly into HTML I started looking for some PoC. My search took me to an online base64 encoder and decoder. This gave me the idea to convert the external image files into base64 string and embed it directly into HTML. On some search I landed up Apache Commons Codec Library which contains a Base64 class which can be used to covert an input stream into a base64 string.
The vi editor in Linux does line wrapping by default. To turn this off for some files with huge lines I use the following command from vi command prompt:
To disable wrap.
:set nowrap
To enable wrap.
:setwrap
I use this ultimate cheat sheet for vi command on Linux whenever in doubt: