Knowledge blog: February 2016

Wednesday, February 17, 2016

Big Performance Mistake - Java Application Development.

1. The framework sample that you use, keep close eye on on following:

a. Every library included in project.
b. Every xml created that's load on runtime.
c. Every default code generate by tool

all above items will decrease a chances of bad performance for application.

Review a debug logs and try to resolve any unknown error and exception that caused but not disturbing application process but it might overloading JVM or database and other related applications / connections.

You might not able to feel any performance issue on development / test server because application is running with sample data / limit number of records and users.

2. Not every architect makes a good decisions:-

Custom measuring for example:-
a. Was impacted by garbage collection
b. just measured overall time but not # SQL Exceptions

DON'T ASSUME you know what code does somebody else developed

3. Use performance test tools dynatrace, New Relic, AppDynamics, HP Load Runner.

4. Idenfity how many sql exection in your code also number of same sql statement executed in your code.
a. Optimize the sql statement or cache data
b Connection equitation time

5. Identify how many number of threads are created and utilized by application and number of call made to API's and time take by each in API.

6. Bad Deployments
a. Different framework / library version between development and production server.
b. Perform Unit Test, Functional Test, Performance Test before deployment

7. Push without a plan ( Idea was great but implementation wasn't correct)
a. Need to check number of images on each page that might cause application slowness.
b. Number of redirection and size of resources are used in each page.
c. Use diagnostics tools to make sure overloading won't happen.

Tuesday, February 16, 2016

Secure tunnels to localhost

Expose local servers behind NATs and firewalls to the public internet over secure tunnels.

> ngrok (https://ngrok.com/download)

Monday, February 15, 2016

Domain Name Server (Bind9)

Install bind and related packages.

# apt-get install bind9 dnsutils

Enter in installed directory

cd /etc/bind/

Open name.conf and add rndc key

# vi name.conf

key "rndc-key" {

algorithm hmac-md5;

secret "XNBYnQX/sv+KJj3JgwPWPA==";

};

key "EMERGEN" {

algorithm hmac-md5;

secret "7ESb2eNqmOs9QTc8WnggPg==";

};

Open vi name.conf.local and add these lines

# vi name.conf.local

zone "emergen.org" in {

file "/etc/bind/master/emergen.org";

type master;

allow-transfer { key EMERGEN; };

};

zone "1.168.192.in-addr.arpa" {

type master;

file "/etc/bind/master/reverse-1.168.192.in-addr.arpa";

allow-transfer { key EMERGEN; };

};

Create directory for forward and reverse file.

# mkdir master

# cd master

Create a forward zone file

# vi emergen.org

$TTL 2d

@ IN SOA ns1.emergen.org. hostmaster.emergen.org. (

8 ; serial

3h ; refresh

1h ; retry

1w ; expiry

1d ) ; minimum

emergen.org. IN NS ns1.emergen.org.

IN MX 10 mail.emergen.org.

IN A 192.168.1.92

www IN A 192.168.1.92

mail IN A 192.168.1.92

Create Reverse zone file

# vi reverse-1.168.192.in-addr.arpa

$TTL 86400;

@ IN SOA ns1.emergen.org. hostmaster.emergen.org. (

23 ; serial

10800 ; Refresh after 3 hours

3600 ; Retry after 1 hour

604800 ; Expire after 1 week

86400 ) ; Minimum TTL of 1 day

;

; Name Servers

;

IN NS ns1.emergen.org.

IN NS ns2.emergen.org.

Restart bind

# /etc/init.d/bind9 restart

Test bind with the help of nslookup command.

# nslookup emergen.org

Server: 192.168.1.92

Address: 192.168.1.92#53

Name: emergen.org

Address: 192.168.1.92

If you'll gate this output that means Naming service is working fine.

LDAP Configuration(On Debian)

LDAP .

LDAP stands for Lightweight Directory Access Protocol.

Reference. Google is the best reference for any kind of problem & also for LDAP :)

LDAP Installation.

when you are going to install ldap in your are syetm than you must have extra

packages installed for ldap.

For Example. Apache2 , PHP5

Apache Installation.

apt-get install apache2

For server-side, HTML-embedded scripting languag supports u have to install libapache2-mod-php5 & also apache2-utils it's a utility programs for webservers.

PHP Installation

apt-get install php5

and php5-common for Common files for packages built from the php and php5-ldap it's LDAP module for php5.

After Installion of apache2 and php5 u have to check them either both r working or not.

Apache testing.

on the webbrowser type http://localhost

It will return u a index.html page but if it's did't it mean there is some problem in ur apache2.

Php testing.

you have to make a php file for cheching php kit it's working or not

Make a php file name test.php

#] vi /var/www/test.php

write some php code or this code is batter for testing

<?php phpinfo(); ?>

Now type this on webbrowser http://localhost/test.php

phpinfo method will return u a complete informationa about php thats installed in ur system.

LDAP Installation

apt-get install slapd it's a OpenLDAP server (slapd).

After installation there is two most important and editable files

/etc/ldap/slapd.con (for server configuration)

/etc/ldap/ldap.con (for client configuration)

when u r going to edit slapd.conf than first make backup for that file.Now you have to change little bit in the configuration file opn it in vi or any other editor.

vi /etc/ldap/slapd.conf

Add suffix it's base of your directory in database

suffix "dc=imtiaz,dc=emergen,dc=org"

also u have to change and add some attributes.

access to attrs=userPassword

by dn="cn=admin,dc=imtiaz,dc=emergen,dc=org" write

by anonymous auth

by self write

by * none

The userPassword by default can be changed by the entry owning it if they are authenticated.

Others should not be able to see it, except the admin entry below.a These access lines apply to database #1 only

or if u feel difficult to edit this file or u don't want to to that than u can configure with the

help of command

dpkg-reconfigure slapd

Add the suffic(i.e. dc=imtiaz,dc=emergen,dc=org) and company name (i.e. Emergen Consulting) and ldap root password. If u select all the option defalut than batter or i u want to set according to ur requirement than u can read and make changes :)

If u wana know about ldap is working or not thats u can check with the builtin command

called

slapdtest

There is a lot of commads they can help u to know about ldap.

Now its time to install phpldapadmin its' web based interface for administering LDAP servers

u can install with the help of

apt-get install phpldapadmin

else if u have a .gz file also u can extract that.

when u complete ur installation or extrection than there is one configuration file called config.php its available in ../phpldapadmin/config/config.php edit that file.

vi ../phpldapadmin/config/config.php

Before > $ldapservers->SetValue($i,'server','name','My LDAP Server');

After < $ldapservers->SetValue($i,'server','name','Imtiaz Directory Service');

Before > // $ldapservers->SetValue($i,'server','host','127.0.0.1');

After < $ldapservers->SetValue($i,'server','host','localhost');

Bwfore > // $ldapservers->SetValue($i,'server','port','389');

After < $ldapservers->SetValue($i,'server','port','389');

Before > // $ldapservers->SetValue($i,'server','base',array(''));

After < $ldapservers->SetValue($i,'server','base',array('dc=imtiaz,dc=emergen,dc=org'));

Before > // $ldapservers->SetValue($i,'server','auth_type','cookie');

After < $ldapservers->SetValue($i,'server','auth_type','session');

Before ># $ldapservers->SetValue($i,'login','dn','cn=Manager,dc=example,dc=com');

After < $ldapservers->SetValue($i,'login','dn','cn=admin,dc=imtiaz,dc=emergen,dc=org');

Before > $ldapservers->SetValue($i,'login','pass','secret');

After < $ldapservers->SetValue($i,'login','pass','emergen');

After change this now it's time to run the phpldapadmin

type this on the web browser

http://ip-address/phpldapadmin or http:// localhost/phpldapadmin (if ur on local system)

u'll see a phpldapadmin login page on the web browser than login & use who ever u want to use and create what ever u what to create :)

[cn,dc that's u added in phpldapadmin config.php file]

Password : emergen

[what ever password u was given on phpldapadmin config file.]

Note:- if ur ladp is not aceepting the login dn or password than it's batter to run

dpkg-reconfigure slapd.

When u finished to create groups & also users than now it's time to check them either they r

completely created and u can use them, u can check that with the help of ssh but befor that u have to installed some more packages and also u have to make changes in some configuration files.

Now install

apt-get install libnss-ldap

apt-get installl libpam-ldap

After installation u have to make changes in file

vi /etc/nsswitch.conf

passwd: files ldap

group: files ldap

shadow: files ldap

vi /etc/pam.d/common-account

account sufficient pam_unix.so

account sufficient pam_ldap.so

vi /etc/pam.d/common-auth

auth sufficient pam_unix.so nullok_secure

auth sufficient pam_ldap.so use_first_pass

vi /etc/pam.d/common-password

password sufficient pam_unix.so nullok obscure min=4 max=8 md5

password sufficient pam_ldap.so use_first_pass debug

vi /etc/pam.d/common-session

session required pam_unix.so

session optional pam_foreground.so

session sufficient pam_ldap.so

After editing all these files try to make ssh with ur added user.

if u want to check ur added user's than u can check with

#] getent passwd

It'll show u all the ldap added user's.

#] ssh ishah@localhost

if ur successful login than ur ldap is working fine :)

Debian Network Configuration

l IP Setting (Static+DHCP)

l DHCP

l DNS (BIND9)

l APT-PROXY

IP Setting (Static+DHCP)

l IP Setting (Static)

Open Interfaces file and add the these lines.

#>vi /etc/networking/interfacse

auto lo

interfaces lo inet loopback

address 127.0.0.1

netmask 255.0.0.0

ath0

iface eth0 inet static

address 192.168.1.12

netmask 255.255.255.0

getway 192.168.1.1

netmask 255.255.255.0

l IP Setting (DHCP)

ath0

iface eth0 inet dhcp

DHCP

l Install DHCP on the debain with the help of

#> apt-get install dhcp3-server

l Open dhcp.conf file to define the range and domain name and etc.

#>vi /etc/dhcp3/dhcp.conf

ddns-update-style none;

option domain-name “emergen.org” ;

option domain-name-server 192.168.2.1;

Increase default-lease-time & Max-lease-time

subnet 192.168.2.0 netmask 255.255.255.0{

range 192.168.2.1 192.168.2.100;

option subnet-mask 255.255.255.0;

option routers 192.168.2.1;

}

If you want to assign the static IP address to any special machine with the help of dhcp

that define the mack address of that machine NIC.

host hostname {

hardware ethernet 00:2E:4B:5R:EE;

fixed-address 192.168.2.15;

}

when ever you are going to restart the DHCP or the system it's have same IP address that u assign.

DNS (BIND9)

l Primary DNS

l Install DIND9

#> apt-get install bind9

l Stop that service

#> /etc/init.d/bind9 stop

l For defining the forword and reverse zone open name.cof file

#>vi /etc/bind/name.conf & define zone's

Don't delete the previous configuration just add these zone in name.conf file.

l Forward Zone

zone “emergen.org”{

type master;

notify no;

file “/etc/bind/emergen.org.db”;

}

l Reverse Zone

Zone “2.168.192.in-addr.arpa”{

type master;

notify no;

file “2.168.192.db”;

}

l Now create the forward & reverse zone file open a file.

#>vi /etc/bind/emergen.org.db

And add this script

$TTL 2d

@ IN SOA emergen.org. root.emergen.org. (

22 ;serial

3h ;refresh

1h ;retry

1w ; expiry

1d ) ; Minimum

emergen.org. IN NS dns1.emergen.org.

IN A 192.168.3.1

www IN A 192.168.3.1

server IN A 192.168.3.1

; If you want to define more host names that just add them

mail IN A 192.168.3.1

smtp IN A 192.168.3.1

pop IN A 192.168.3.1

l Now create reverse zone file

#> vi /etc/bind/2.168.192.db

And add these line

$TTL 2d

@ IN SOA emergen.org. root.emergen.org.(

2004111601 ; Serial

8H ; Refresh

4H ; Retry

4W ; Expire

1D ) ; Default TTL

IN NS dns1.emergen.org.

1.3.168.192.in-addr.arpa. IN PTR www.emergen.org.

l Start the BIND9 Service

#> /etc/init.d/bind9 start

l Test your BIND9 configuration

#> ping www.emergen.org or mail.emergen.org

#>nslookup emergen.org or mail.emergen.org

l Secondary DNS Server

l Again install bind9 DNS package with the same configuration files on second machine just you have to add some extra lines.

Add Zones in name.conf

zone "emergen.org"{

type slave;

file "/etc/bind/emergen.org.db";

masters{

192.168.3.1;

};

zone "3.168.192.in-addr.arpa"{

type slave;

file "/etc/bind/3.168.192.db";

masters{

192.168.3.1;

};

l Create file for foreword zone.

vi /etc/bind/emergen.org