IIS on Windows Server Core

 Windows famous because of the GUI to make everything easier. But when you have  windows server core under your management without any documentation, this will make you wonder, why install windows server Core. Is more secure than windows server ?We not talk about security now. What we are going to talk here is installation of SSL certificate which will be use by the Webservice.Quite easy with some command, but the diligence to look for what command should you run is the aha moment.Here i document my journey and the process to do it.1. You will need other windows server GUI to be able manage the windows core server with GUI.2. Install...

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Compile Erlang using Kerl with crypto module

When working with erlang, we can use old version to run our erlang app which are not yet upgraded.This multiple erlang version run like python env if you come from python.So in erlang we using Kerl which can switch to multiple erlang version at runtime. So here we go.We are using Debian 10.x buster. Some prerequisite before able to finish are install the dev tools.# apt-get install build-essential autoconf libncurses5-dev openssl libssl-dev fop xsltproc...

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panic cannot login to linux

Panic ! Thats what occurs when a critical systems you manage cannot login , but the service was running properly.Recently i do some changes on the /etc/security/limits.conf and it make all lockout. No SSH can be done, but all the service was running properly.To the rescue, we need to login to the systems and revert back changes, and to do that we need to go into single mode.We do on Centos 7.x systems which is the grub boot loader is different than the old version.So how to do it step by step, and no panic. Reboot your machine and immidiately go to rescue mode.Chose one boot options and press "e" to change the entryLook for below entry :linux16...

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Compiling GoLang application

When using Golang basic setup need to be done to able compile all application based on golang in github.To do that install golang then set in your home directory.let say /home/geek/go/inside the folder create a src folder, and put all the go app you want to compile.Then remember to set env variable GOPATH.in ~/.bashrc set :GOPATH = /home/geek/goExample you have a killer-app download from github with go source code.Put it inside /home/geek/go/src/killer-app/Then do this :$ cd /home/geek/go/src/killer-app/$ go get ./...$ go buildThen there will be a file created from the compile called killer-app Then prof...

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Stafull and Stateless widget in Flutter

In flutter we have 2 type of widget, Statefull and stateless. Difference are the stateless widget will never changes after it rendered. Meantime statefull widget can be change in the future after the widget rendered.There are difference on how to use it. Because flutter using inheritance of the widget, we will always override some of the function / properties of the widget. There will be a lot of inheritance method in flutter.Lets go for the stateless widget first. On the stateless widget, the one we override are the build function.Below is the example code.import 'package:flutter/material.dart';void main() => runApp(MyApp());class MyApp extends...

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Basic Flutter Scaffolding

Flutter makes the development enjoyable and fast.Here are some of the template for create a basic layout.We create an app with App bar and a body.import 'package:flutter/cupertino.dart';import "package:flutter/material.dart";void main() => runApp(MyApp());class MyApp extends StatelessWidget {@override Widget build(BuildContext context){ return MaterialApp( title: 'My Work Timer', theme: ThemeData( primarySwatch: Colors.blueGrey, ), home: Scaffold( appBar: AppBar( title: Text('My Killer App'), ), body: Center( child: Text('My Killer APp'), ), ), ...

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Mobile Development with Flutter

Nowdays, mobile development not need to be tricky and hard.Old timers for mobile dev will use java fro android and object C for ios development, which means 2 code for 2 platform Android and IOS.Other path was hybrid using web development technique which just load a Web view in the application, so developer can use Web development tools and style to develop mobile app.Now, we have Google who develop Flutter on top of Dart which will make the Java slogan "code once run on any mobile platform (Android / IOS) but now with happiness.All in flutter just a widget and tooling all free and available and it also beautifull on the app generated because...

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Securing your Web services using Nginx

If we have an API service and want to publish to public, better use a reverse proxy like nginx to handle all the dirty traffic trying to taken down your services. With Nginx you will make your API server live prosper and not minding the dirty request which should not coming on your server if not using Nginx in front of it. So lets do the Nginx configuration for securing your backend API server.     add_header Cache-Control public;    ...

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Monitoring tools in the new age with Grafana

We know for old school monitoring tools are using Nagios, Cacti, CollectD. Well, that's what i use on my job to monitoring infrastructure. No fancy graphic and display, no filter , only plain time range value with the monitored data. Now, we see Grafana. I try grafana and its looks a like elastic kibana. Well, apparantly Grafana was a fork of Kibana 3.0 . Grafana is Free to use, but also have enterprise version which have support. With grafana...

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Create a Services in linux box

In linux box, everything runs at startup is a service. Service located on  /etc/systemd/system/servicename.service Step to create a service are : 1. Create a service user account 2. Change ownership of config file to the service account 3. Create a service file to load when startup Create service user account the secure way : $ sudo useradd --no-create-home --shell /bin/false blackbox_exporter Here are template for create a service...

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Exchange server error 452-4-3-1-insufficient-system-resources

When Microsoft Exchange have problem cannot receive any email from other party, there will be a lot of things can be happened. But make sure you pin point the exact issue by looking at the server event logs for exchange. Also if possible to get the NDR report from the sending party so we can know exactly what exchange spit out when error happening. Usually a mature mail systems will have specific error so administrator can resolve the problem. On...

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Squid delay pools setup

Squid can do bandwith management and separate speed access based on group. Below example of setup : ########################################### define networksacl all src 0.0.0.0/0.0.0.0acl unlimited src "/etc/squid/unlimited.txt"acl our_1mbps src "/etc/squid/our_1mbps.txt"acl our_512kbps src "/etc/squid/our_512kbps.txt"acl our_256kbps src "/etc/squid/our_256kbps.txt"######### give accesshttp_access allow unlimitedhttp_access allow our_1mbpshttp_access allow our_512kbpshttp_access allow our_256kbpshttp_access deny all##### define delay poolsdelay_pools 4delay_class 1 2delay_access 1 allow unlimiteddelay_access 1 deny alldelay_parameters 1...

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