Magnus K Karlsson: 2014

December 22, 2014

SyntaxHighlighter

Supported styling.

https://github.com/rwz/SyntaxHighlighter/blob/master/demos/autoloader.html

Java EE 7 Maven Dependency

In my previous blog about Java EE 6 Maven Dependency a wrote about the crippled javaee-api maven dependency in maven central.

That is finally fixed in EE 7.

<dependency>
    <groupid>javax</groupid>
    <artifactid>javaee-api</artifactid>
    <version>7.0</version>
    <scope>provided</scope>
</dependency>

December 21, 2014

Java EE 6 Maven Dependency

The EE 6 classes are available in maven central.

<dependency>
    <groupid>javax</groupid>
    <artifactid>javaee-api</artifactid>
    <version>6.0</version>
    <scope>provided</scope>
</dependency>

But when running unit test against them you receive the below error. Thats because they do not contain implementation classes, only api class.

java.lang.ClassFormatError: Absent Code attribute in method that is not native or abstract in class file javax/persistence/LockModeType
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClassCond(ClassLoader.java:632)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:616)
        at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
        at java.net.URLClassLoader.access$000(URLClassLoader.java:58)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:197)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:190)

So in practice, the dependecy is in real life unusable. Instead you must use api classes from specific vendors like JBoss.

<dependency>
    <groupid>org.jboss.spec</groupid>
    <artifactid>jboss-javaee-6.0</artifactid>
    <version>1.0.0.Final</version>
    <type>pom</type>
    <scope>provided</scope>
</dependency>

Java EE 7 Deployment Descriptors

Deployment descriptors are like configuration files.

The below sites summaries all xml schemas defintions for all EE 7 deployment descriptors.

http://antoniogoncalves.org/2013/06/04/java-ee-7-deployment-descriptors/

Java EE 6 Interceptors 1.0 (JSR318)

Introduction

Interceptor was in EE 5 introduced in EJB 3.0, see EJB3 Interceptors javax.ejb.AroundInvoke. In EE 6 that was taken out and made generic into Interceptors (JSR318), package javax.interceptor.*.

You can call Interceptor in EE 6 in two way:

By annotating method or class with @javax.interceptor.Interceptors(MyInterceptor.class)
Create custom Annotation with Annotation @javax.interceptor.InterceptorBinding and annotate with that you method or class.

Example

Your custom Interceptor.

package se.magnuskkarlsson.example.interceptor;

import java.io.Serializable;

import javax.interceptor.AroundInvoke;
import javax.interceptor.Interceptor;
import javax.interceptor.InvocationContext;

import org.apache.log4j.Logger;

@Audit
@Interceptor
public class AuditInterceptor implements Serializable {

    private static final long serialVersionUID = 1L;

    private static final Logger log = Logger.getLogger(AuditInterceptor.class);

    @AroundInvoke
    public Object intercept(InvocationContext ctx) throws Exception {
        log.info("### Entering method: " + ctx.getMethod().getName()
                + " in class " + ctx.getMethod().getDeclaringClass().getName());

        return ctx.proceed();
    }
}

Interception in a POJO.

package se.magnuskkarlsson.example.interceptor;

import javax.interceptor.Interceptors;

public class DemoPOJO {

    @Interceptors(AuditInterceptor.class)
    public String sayHello() {
        return "Hello POJO";
    }
}

Interception in a Stateless Session Bean.

package se.magnuskkarlsson.example.interceptor;

import javax.ejb.Stateless;
import javax.interceptor.Interceptors;

@Stateless
public class DemoSLSB {

    @Interceptors(AuditInterceptor.class)
    public String sayHello() {
        return "Hello SLSB";
    }
}

beans.xml located for war in WEB-INF/.

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/beans_1_0.xsd">

</beans>

To use the Interceptor you must let weld create the intercepted class, otherwise will weld never knew about the interceptor and hence will the interceptor never work.

Example usage from a Servlet.

package se.magnuskkarlsson.example.interceptor;

import java.io.IOException;
import java.io.PrintWriter;

import javax.ejb.EJB;
import javax.inject.Inject;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet("/audit")
public class DemoServlet extends javax.servlet.http.HttpServlet {

    private static final long serialVersionUID = 1L;

    @Inject
    private DemoPOJO pojo;

    @EJB
    private DemoSLSB slsb;

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {

        req.setCharacterEncoding("UTF-8");
        resp.setCharacterEncoding("UTF-8");
        resp.setContentType("text/html; charset=UTF-8");
        PrintWriter out = null;
        try {
            out = resp.getWriter();
            out.println("<html><body>");
            out.println("<h1>" + pojo.sayHello() + "</h1>");
            out.println("<h1>" + slsb.sayHello() + "</h1>");
            out.println("</html></html>");
        } finally {
            if (out != null) {
                out.close();
            }
        }
    }
}

Limitation

You cannot use Interceptor directly in servlets, see https://java.net/projects/servlet-spec/lists/jsr340-experts/archive/2012-02/message/0.

Taking Snapshot in Ubuntu

When taking snapshot in Ubuntu you could always use the predefined keyboard shortcuts, see https://help.ubuntu.com/community/KeyboardShortcuts#Desktop_shortcuts

A better tool is to use the gnome-screenshot tool.

You can install via `sudo apt-get install gnome-screenshot`

How to Manage Properties Files in JBoss Module

From JBoss AS 7 and EAP 6 forth, classloading have changed and all jar dependencies are packaged and loaded as jboss modules.

Besides dependency jar in a module you also might need to be able to configure it for different server environment. The best way and maybe the natural way, is to make use of a java properties file.

This is a good practice, now you can RPM package your custom module. This is how Red Hat do with JBoss EAP 6. With RPM packing you have now the capability of versioning your module and to centrally install it from, e.g. Red Hat Satellite. And finally centrally configure the property file from, e.g. Satellite 6 via Puppet.

But there is classloading gotchas. You need to add <resource-root path="."/> to you module.xml.

See https://developer.jboss.org/wiki/HowToPutAnExternalFileInTheClasspath for longer description.

List JNDI Tree Entries with JBoss CLI

To list all JNDI entries with JBoss CLI.

First start JBoss CLI.

$ ./jboss-cli.sh --connect

Then execute.

[standalone@localhost:9999 /] /subsystem=naming:jndi-view

How to Deploy Sources and Javadoc Jar

When deploying a snapshot release or if you by some other reason want to generate sources or javadoc jar, you could always configure maven-source-plugin and maven-javadoc-plugin and hook them in maven life cycle.

But that is not necessary in maven uber pom is that already defined for release. You can reuse that by adding -DperformRelease=true

mvn -DperformRelease=true [goals]

Different example of usage:

Local build with sources and javadoc jar generation

mvn -DperformRelease=true clean install

Deploy target. Use only with snapshot version. Then deploy means snapshot publishing to defined snapshot repository.

mvn -DperformRelease=true clean install deploy

Overview EE and JBoss EE Compliance

Overview of EE evolution

The capabilities and what is supported out of the box in EE, is increasing from next version to next version. The drive behind the new feature are:

Common task are finally included in standard EE.
Better maven dependency management.
Better test support (FINALLY!), but in this area, more can be done.

[http://en.wikipedia.org/wiki/Java_EE_version_history]

Summary of JBoss AS, EAP and new Wildfly EE Compliance

EE 4 - JBoss AS 4.X, JBoss EAP 4 *

EE 5 - JBoss AS 5.1, JBoss EAP 5 *

EE 6 - JBoss AS 7.1, JBoss EAP 6 *

EE 7 - Wildfly 8.x, JBoss EAP 7 * (release date Q2-Q3? 2015)

*) The EAP is forked from AS/Wildfly version left to it, but with much more quality (tested, patched, security compliance testing, security patched), documentation and with support.

Reference

October 22, 2014

Cloning Machine in KVM and Getting "Device eth0 does not seem to be present”

To fix this problem follow http://aaronwalrath.wordpress.com/2011/02/26/cloned-red-hatcentosscientific-linux-virtual-machines-and-device-eth0-does-not-seem-to-be-present-message/.

August 17, 2014

Helpful CSS Cheat Sheets

Very good comprehensive CSS cheat sheets summarized on one single page http://slodive.com/freebies/css-cheat-sheets/.

August 12, 2014

RHEL 6 Synchronize Time Using Other NTP Peers

Introduction

In this blog will I show how to setup a NTP server and perform NTP synchronizing on remote server.

Server Installation

yum install ntp ntpdate -y

Server Configuration

vi /etc/ntp.conf
...
restrict 192.168.1.0 mask 255.255.255.0 nomodify notrap
...

The server IP is 192.168.1.240 and is located in 192.168.1.0/24 subnet.

Server Firewall

vi /etc/sysconfig/iptables
...
-A INPUT -m state --state NEW -m udp -p udp --dport 123 -j ACCEPT
-A INPUT -m state --state NEW -m tcp -p tcp --dport 123 -j ACCEPT
...

Server Start

service ntpd restart; chkconfig ntpd on

Client Installation

yum install ntp ntpdate -y

Client Start

service ntpd restart; chkconfig ntpd on

Client Test

Query your NTP server, but NOT set time. If query return higher stratum than 16, just wait a little and then requery.

$ ntpdate -q 192.168.1.240
server 192.168.1.240, stratum 3, offset -0.000189, delay 0.02585
12 Aug 16:43:45 ntpdate[1700]: adjust time server 192.168.1.240 offset -0.000189 sec

Client Set NTP Server

$ sudo vi /etc/ntp.conf 
...
server 192.168.1.240
#server 0.rhel.pool.ntp.org iburst
#server 1.rhel.pool.ntp.org iburst
#server 2.rhel.pool.ntp.org iburst
#server 3.rhel.pool.ntp.org iburst
...

And finally you need to restart ntpd service.

August 10, 2014

RHEL 6 Configure an MTA to Forward (Relay) Email Through a Smart Host.

Introduction

A relay mail server (MTA) is a intermediate server that forwards email to the final delivery mail server (MDA), i.e. writes message to default store /var/spool/mail/${USER}.

Remote Client --> Mail Transfer Agent, MTA (192.168.1.11) --> Mail Delivery Agent, MDA (192.168.1.12)

Configuration MTA

$ vi /etc/postfix/main.cf
...
myhostname = san.magnuskkarlsson.com
...
mydomain = magnuskkarlsson.com
...
myorigin = $mydomain
...
inet_interfaces = all
...
mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain
...
mynetworks = 192.168.1.0/28, 127.0.0.0/8
...
relayhost = 192.168.1.12

If you want MTA to ONLY transfer mail then set 'mydestination = '. With the above configuration the MTA will delivers local users email from remote client.

Restart service to let configuration take effects.

service postfix restart; chkconfig postfix on

Check that SMTP port 25 (TCP) is open in iptables. If you need to update the configuration, don't forget to restart iptables service.

$ vi /etc/sysconfig/iptables
...
-A INPUT -p tcp -m state --state NEW -m tcp --dport 25 -j ACCEPT 
...

Configuration MDA

$ vi /etc/postfix/main.cf
...
myhostname = rhel6.magnuskkarlsson.com
...
mydomain = magnuskkarlsson.com
...
myorigin = $mydomain
...
inet_interfaces = all
...
mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain
...
mynetworks = 192.168.1.0/28, 127.0.0.0/8
...
relayhost =

Do not forget to restart postfix service after configuration changes.

Create ordinary unix user for test, via command adduser mail2.

Check iptables SMTP port 25 (tcp) is open. Update if needed and restart iptables service.

If SELinux is active (default), check that default SELinux boolean for postfix is on.

$ getenforce 
Enforcing

# getsebool -a | grep postfix
allow_postfix_local_write_mail_spool --> on

Test

Now we are ready to test by sending mail from a remote client.

$ telnet 192.168.1.11 25
Trying 192.168.1.11...
Connected to 192.168.1.11.
Escape character is '^]'.
220 san.magnuskkarlsson.com ESMTP Postfix
EHLO 192.168.1.11
250-san.magnuskkarlsson.com
250-PIPELINING
250-SIZE 10240000
250-VRFY
250-ETRN
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN
MAIL FROM: foo@bar.com
250 2.1.0 Ok
RCPT TO: mail2@rhel6.magnuskkarlsson.com
250 2.1.5 Ok
DATA
354 End data with <CR><LF>.<CR><LF>
Subject: hello 
sbj 
.
250 2.0.0 Ok: queued as 92E1040EB2
^]

telnet&gr; quit
Connection closed.

Now verify that mail was delivered on MDA (192.168.1.12).

$ cat /var/spool/mail/mail2 
...
From foo@bar.com  Sun Aug 10 01:18:34 2014
Return-Path: <foo@bar.com>
X-Original-To: mail2@rhel6.magnuskkarlsson.com
Delivered-To: mail2@rhel6.magnuskkarlsson.com
Received: from san.magnuskkarlsson.com (unknown [192.168.1.11])
 by rhel6.magnuskkarlsson.com (Postfix) with ESMTP id 2ADC210CB
 for <mail2@rhel6.magnuskkarlsson.com>; Sun, 10 Aug 2014 01:18:34 +0200 (CEST)
Received: from 192.168.1.11 (unknown [192.168.1.122])
 by san.magnuskkarlsson.com (Postfix) with ESMTP id 92E1040EB2
 for <mail2@rhel6.magnuskkarlsson.com>; Sun, 10 Aug 2014 19:01:59 +0200 (CEST)
Subject: hello 

sbj

August 8, 2014

RHEL 6 Postfix Aliases

Introduction

In my previos blog I described to configure and run MTA with postfix. Here I will describe how to make aliases.

Configuration

Start

Create alias

Now to let this take effect you must run the program newaliases.

Test

On remote client send mail to root@san.magnuskkarlsson.com.

And to verify on server.

RHEL 6 Configure a Mail Transfer Agent (MTA) to Accept Inbound Email From Other Systems

Installation

Configuration

Start

Firewall

Add TCP port 25 for SMTP.

Then restart firewall, to let new configuration take effect.

Test

First create a test user on server.

Then on remote client, we use telnet to send mail. For details see http://magnus-k-karlsson.blogspot.se/2014/06/how-to-send-mail-from-command-line-with.html.Here follows a summary.

Now check mail on server.

Reference

man 5 postconf

August 7, 2014

RHEL 6 FTP Configure Anonymous-Only Download.

Installation

yum install vsftpd -y

Configuration

$ vi /etc/vsftpd/vsftpd.conf
...
# Allow anonymous FTP?
anonymous_enable=YES
..
# Uncomment this to allow local users to log in.
local_enable=NO
...
# Uncomment this to enable any form of FTP write command.
write_enable=NO
...

Start

service vsftpd restart; chkconfig vsftpd on

Firewall

$ vi /etc/sysconfig/iptables
...
-A INPUT -p tcp -m state --state NEW -m tcp --dport 21 -j ACCEPT 
...

$ vi /etc/sysconfig/iptables-config
...
IPTABLES_MODULES="nf_nat_ftp nf_nat_tftp"
...

$ service iptables restart
iptables: Setting chains to policy ACCEPT: filter          [  OK  ]
iptables: Flushing firewall rules:                         [  OK  ]
iptables: Unloading modules:                               [  OK  ]
iptables: Applying firewall rules:                         [  OK  ]
iptables: Loading additional modules: nf_nat_ftp nf_nat_tft[  OK  ]

Test

Create test data.

$ echo "Hello" >> /var/ftp/pub/hello.txt

$ restorecon -RFv /var/ftp/pub/hello.txt 
restorecon reset /var/ftp/pub/hello.txt context unconfined_u:object_r:public_content_t:s0->system_u:object_r:public_content_t:s0

And download it from remote host.

$ lftp 192.168.1.11
lftp 192.168.1.11:~> ls
drwxr-xr-x    2 0        0            4096 Aug 07 19:22 pub
lftp 192.168.1.11:/> cd pub/
lftp 192.168.1.11:/pub> ls
-rw-r--r--    1 0        0               6 Aug 07 19:22 hello.txt
lftp 192.168.1.11:/pub> get hello.txt 
6 bytes transferred
lftp 192.168.1.11:/pub> exit

# cat hello.txt 
Hello

RHEL 6 Configure a Caching-Only Name Server to Forward DNS Queries

Installation

yum install bind bind-chroot bind-utils -y

Configuration

$ vi /etc/named.conf
...
    listen-on port 53 { any; };
    listen-on-v6 port 53 { any; };
...
    allow-query     { 192.168.1.0/24; };
    forwarders      { 192.168.1.1; };
...
    dnssec-validation no;
...

Start

service named restart; chkconfig named on

Test

$ nslookup www.sunet.se 192.168.1.11
Server:  192.168.1.11
Address: 192.168.1.11#53

Non-authoritative answer:
www.sunet.se canonical name = vision.sunet.se.
Name: vision.sunet.se
Address: 192.36.171.156

Firewall

$ vi /etc/sysconfig/iptables
...
-A INPUT -p tcp -m state --state NEW -m tcp --dport 53 -j ACCEPT 
-A INPUT -p udp -m state --state NEW -m udp --dport 53 -j ACCEPT
...

June 30, 2014

Packt is offering all of its eBooks and Videos at just $10 each for 10 days

Packt is celebrating 10 years anniversary and is celebrating that with offering all of its eBooks and Videos at just $10 each for 10 days.
http://bit.ly/1k5EUYD

How to Send Mail from the Command Line with Telnet

You can easily test your mail configuration from a linux server with telnet.

$ telnet rhel1 25
Trying 172.168.1.1...
Connected to rhel1.
Escape character is '^]'.
220 rhel1.localdomain ESMTP Postfix
<b>HELO rhel1</b>                        # Note that "HELO" is not a misspelled. It is the command for telnet services.
250-rhel1.localdomain
250-PIPELINING
250-SIZE 10240000
250-VRFY
250-ETRN
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN
<b>MAIL FROM: ivan@rhel2</b>
250 2.1.0 Ok
<b>RCPT TO: david@rhel1</b>
250 2.1.5 Ok
<b>DATA</b>
354 End data with <CR><LF>.<CR><LF>
<b>Subject: Subject goes here.</b>
<b>Body goes here.</b>
<b>.</b>                                # End body with '.' and Enter                            
250 2.0.0 Ok: queued as 5C3E5E12EA
                                 # Quite interactive mail session with ctrl + ']'
<b>quit</b>
221 2.0.0 Bye
Connection closed by foreign host.

For a more detail description, please see http://www.ehow.com/how_5209651_use-sendmail-command-line.html.

Server Comaparison between RHEL and Windows

An interesting comparison (in swedish) between RHEL server and Windows server.

Source:http://techworld.idg.se/2.2524/1.498006/windows-vs-linux---nu-avgors-kampen

How to Install KVM on Ubuntu 14.04 LTS (Trusty)

Prerequisite

Verify that you have enabled virtualization in BIOS. For detail see Virtualization with KVM on RHEL 6

Install

Install required packages.

$ sudo apt-get install qemu-kvm libvirt-bin bridge-utils virt-manager

Run

Now you ready to run virt-manager and install new virtual guests.

$ sudo virt-manager

If you are new to kvm, please read Virtualization with KVM on RHEL 6 for a detailed description.

June 21, 2014

Tweak Unity in Ubuntu 14.04

The preferred way to tweak the user interface (Unity) in Ubuntu 14.04 is via the unity-tweak-tool. You can also use ccsm - CompizConfig Settings Manager, but I would recommend to stick with the recommended unity-tweak-tool, since settings can be messed up, when manipulating settings with different tools.

To install:

$ sudo apt-get install unity-tweak-tool

And if you have got lost when configure, you can always get back to original configuration with:

$ unity-tweak-tool --reset-unity

Static Routes with RHEL 6

The new way to add static routes in RHEL 6 is

$ vi /etc/sysconfig/network-scripts/route-<interface>

ADDRESS0=X.X.X.X
NETMASK0=X.X.X.X
GATEWAY0=X.X.X.X

Or alternative via the old ip command style.

$ vi /etc/sysconfig/network-scripts/route-<interface>

X.X.X.X/Y via X.X.X.X dev <interface>

And to set the default gateway.

$ vi /etc/sysconfig/network
...
GATEWAY=X.X.X.X
...

How to Install Minecraft in Ubuntu 14.04

Kids go crazy over the swedish developed game Minecraft. Below is a link how to install it on Ubuntu 14.04.

http://ubuntuhandbook.org/index.php/2014/04/install-minecraft-in-ubuntu-14-04/

How to Merge Multiple PDF Files in Ubuntu

You can easily merge several pdf files into on file with 'pdftk - A handy tool for manipulating PDF'

Example how to merge file1.pdf and file2.pdf to mergedfile.pdf.

$ pdftk file1.pdf file2.pdf cat output mergedfile.pdf

June 12, 2014

Convert MP4 to MP3 on Ubuntu 14.04 Trusty

There is a program available on Ubuntu youtube-dl, that can download videos from youtube.com or other video platforms. But it stores the file in mp4, since it contains video. But sometimes you do not want the video and only the audio. To extract only the audio part, you can use the pacpl comamnd line tool.

pacpl --to mp3 -v -r- -bitrate 320 targetfile.mp4

June 9, 2014

Bash Programming Documentation in RHEL 6

I'm not a bash script guru, so I need documentation. Here I will show you how to get/install that for RHEL 6.

All the BASH documentation is available via the bash-doc RPM, but it is not located in the RHEL base channel (rhel-x86_64-server-6), but in the RHEL Server Optional channel (rhel-x86_64-server-optional-6).

To add or remove channels from the command line you use the rhn-channel.

rhn-channel --channel=rhel-x86_64-server-optional-6 --add --user=<RHNREG_USERNAME> --password=<RHNREG_PASSWORD>

Now you are ready to install the bash-doc package.

yum install bash-doc

And to list the installed files.

$ rpm -ql bash-doc
...
/usr/share/doc/bash-4.1.2/doc/bashref.pdf
...

And the most interesting file is the BASH Reference Manual, as highlighted above.

May 20, 2014

Configure RHEL 6 as Router

Introduction

In this blog I will show you how to configure a RHEL 6 server as router for LAN (eth1) and WAN (eth0).

Enable IP forwarding

First we need to enable IP forwarding.

$ sysctl -w "net.ipv4.ip_forward=1"
net.ipv4.ip_forward = 1

And to verify.

$ sysctl net.ipv4.ip_forward
net.ipv4.ip_forward = 1

To make it permanent, you need to edit /etc/sysctl.conf.

$ grep "^net.ipv4.ip_forward" /etc/sysctl.conf 
net.ipv4.ip_forward = 1

Configure Router Server Network

Before we begin, we disable NetworkManager.

$ service NetworkManager stop
$ chkconfig NetworkManager off

Then we manually edit our network configuration files.

We begin with our WAN (eth0) card.

$ cat /etc/sysconfig/network-scripts/ifcfg-eth0
DEVICE=eth0
TYPE=Ethernet
HWADDR=64:70:02:11:d9:83
NM_CONTROLLED=no
ONBOOT=yes
BOOTPROTO=none
IPADDR=192.168.1.100
NETMASK=255.255.255.0
GATEWAY=192.168.1.1
DNS1=192.168.1.1

And continue with our LAN (eth1) card.

$ cat /etc/sysconfig/network-scripts/ifcfg-eth1
DEVICE=eth1
TYPE=Ethernet
HWADDR=64:70:02:13:CB:95
NM_CONTROLLED=no
ONBOOT=yes
BOOTPROTO=none
IPADDR=192.168.2.100
NETMASK=255.255.255.0
GATEWAY=192.168.1.1
DNS1=192.168.1.1

The above HWADDR is different for your environment. To get yours use ifconfig.

$ ifconfig 
eth0      Link encap:Ethernet  HWaddr 64:70:02:11:D9:83  
...
eth1      Link encap:Ethernet  HWaddr 64:70:02:13:CB:95  
...

Finally restart network service and check new ip addresses are set, via ip or ifconfig command.

$ service network restart

$ ip addr show
...
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
...
    inet 192.168.1.100/24 brd 192.168.1.255 scope global eth0
...
3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
...
    inet 192.168.2.100/24 brd 192.168.2.255 scope global eth1
...

iptables

Now we are ready to configure iptables. First flush existing rules.

$ iptables -t filter -F
$ iptables -t nat -F
$ iptables -t mangle -F

Then add the MASQUERADE roule to the WAN (eth0) card

$ iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE

Finally save iptables configuration.

$ service iptables save

Test

I have connected a separate machine on LAN and configure it manually with static IP.

$IP: 192.168.2.3
NETMASK: 255.255.255.0
GATEWAY: 192.168.2.100
DNS1: 192.168.2.100

Now we can ping 192.168.2.100 (gateway), 192.168.1.100 (rhel 6 router), 192.168.1.1 (WAN GATEWAY) and finally www.google.com.

April 22, 2014

How To Install and Configure SAMBA Server on RHEL 6

Installation

$ yum -y install samba samba-client

$ service smb restart

Configuration

The default configuration works just fine.

$ cat /etc/samba/smb.conf
...
[global]
    workgroup = MYGROUP
    server string = Samba Server Version %v
    log file = /var/log/samba/log.%m
    max log size = 50

    security = user
    passdb backend = tdbsam

    load printers = yes
    cups options = raw

[homes]
    comment = Home Directories
    browseable = no
    writable = yes

[printers]
    comment = All Printers
    path = /var/spool/samba
    browseable = no
    guest ok = no
    writable = no
    printable = yes
...

Security

Having 'security = user' means we need a UNIX account. Lets create one.

$ useradd -s /sbin/nologin winuser1

And set samba password for account.

$ smbpasswd -a winuser1

Firewall

$ iptables -I INPUT 5 -m state --state new -p tcp --dport 445 -j ACCEPT

$ iptables -I INPUT 6 -m state --state new -p udp --dport 137 -j ACCEPT

$ iptables -I INPUT 7 -m state --state new -p udp --dport 138 -j ACCEPT

$ iptables -I INPUT 8 -m state --state new -p tcp --dport 139 -j ACCEPT

Test

Now lets test it from a remote client. First lets list all shares on host.

$ smbclient -L 127.0.0.1 -U winuser1
Enter winuser1's password: 
Domain=[MYGROUP] OS=[Unix] Server=[Samba 3.6.9-168.el6_5]

 Sharename       Type      Comment
 ---------       ----      -------
 IPC$            IPC       IPC Service (Samba Server Version 3.6.9-168.el6_5)
 winuser1        Disk      Home Directories
Domain=[MYGROUP] OS=[Unix] Server=[Samba 3.6.9-168.el6_5]

 Server               Comment
 ---------            -------

 Workgroup            Master
 ---------            -------

And to mount it.

$ mount -t cifs -o user=winuser1 //192.168.1.16/winuser1 /remote

Finally lets test to write to winuser1 home directory.

$ echo "Hello" >> /remote/foo
-bash: /remote/foo: Permission denied

This did not go well. The missing configuration is SELinux.

SELinux

On the SAMBA server, run the following command, if you want to share home directories via samba.

$ setsebool -P samba_enable_home_dirs on

Now lets get back to client and un mount and the remount and write and read and that should be successful.

Different Way to Mount NFS in RHEL6

Automounting

The below will auto mount the user 'ldapuser1' home directory with rw permission on nfs.server.com.

$ vi /etc/auto.master
/home /etc/auto.home

$ vi /etc/auto.home
ldapuser1 -rw nfs.server.com:/export/path/ldapuser1

Manual

You can manually mount a nfs exported directory to a local directory /remote.

$ mount -t nfs nfs.server.com:/export/path /remote

Mount at boot

$ vi /etc/fstab
nfs.server.com:/export/path    /remote    nfs    defaults    0 0

How to Install and Configure NFS Sharing on RHEL 6

Installation

yum groupinstall nfs-file-server

To get nfs to work we need to install and start rpcbind and nfslock. Double check that is done.

chkconfig rpcbind on
service rpcbind restart

chkconfig nfslock on
service nfslock restart

Now we are ready to start NFS.

service nfs restart

Finally lets test our new NFS server.

showmount -e 127.0.0.1

This will return a empty export list, without error.

Firewall

To be able to access NFS exports remotely, we need to open certain ports in the firewall. To investigate which one, we use the command rpcinfo.

rpcinfo -p

This will return quite some ports. To lock down which port that are used please uncomment all ports in NFS conf file.

$ grep -i port /etc/sysconfig/nfs
RQUOTAD_PORT=875
LOCKD_TCPPORT=32803
LOCKD_UDPPORT=32769
MOUNTD_PORT=892
STATD_PORT=662
STATD_OUTGOING_PORT=2020
RDMA_PORT=20049

Now restart NFS service and lets start open ports.

service nfs restart

And after opening all ports the iptables should look like.

$ iptables -vnL --line-numbers
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
num   pkts bytes target     prot opt in     out     source               destination         
1     1540  127K ACCEPT     all  --  *      *       0.0.0.0/0            0.0.0.0/0           state RELATED,ESTABLISHED 
2        0     0 ACCEPT     icmp --  *      *       0.0.0.0/0            0.0.0.0/0           
3        0     0 ACCEPT     all  --  lo     *       0.0.0.0/0            0.0.0.0/0           
4        0     0 ACCEPT     tcp  --  *      *       0.0.0.0/0            0.0.0.0/0           state NEW tcp dpt:111 
5        1    84 ACCEPT     udp  --  *      *       0.0.0.0/0            0.0.0.0/0           state NEW udp dpt:111 
6        0     0 ACCEPT     udp  --  *      *       0.0.0.0/0            0.0.0.0/0           state NEW udp dpt:60584 
7        0     0 ACCEPT     tcp  --  *      *       0.0.0.0/0            0.0.0.0/0           state NEW tcp dpt:56907 
8        1    60 ACCEPT     tcp  --  *      *       0.0.0.0/0            0.0.0.0/0           state NEW tcp dpt:892 
9        0     0 ACCEPT     udp  --  *      *       0.0.0.0/0            0.0.0.0/0           state NEW udp dpt:892 
10       0     0 ACCEPT     tcp  --  *      *       0.0.0.0/0            0.0.0.0/0           state NEW tcp dpt:2049 
11       0     0 ACCEPT     udp  --  *      *       0.0.0.0/0            0.0.0.0/0           state NEW udp dpt:2049 
12       0     0 ACCEPT     udp  --  *      *       0.0.0.0/0            0.0.0.0/0           state NEW udp dpt:32769 
13       0     0 ACCEPT     tcp  --  *      *       0.0.0.0/0            0.0.0.0/0           state NEW tcp dpt:32803 
14       0     0 LOG        all  --  *      *       0.0.0.0/0            0.0.0.0/0           LOG flags 0 level 4 
15       0     0 REJECT     all  --  *      *       0.0.0.0/0            0.0.0.0/0           reject-with icmp-host-prohibited 

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
num   pkts bytes target     prot opt in     out     source               destination         
1        0     0 REJECT     all  --  *      *       0.0.0.0/0            0.0.0.0/0           reject-with icmp-host-prohibited 

Chain OUTPUT (policy ACCEPT 122 packets, 17748 bytes)
num   pkts bytes target     prot opt in     out     source               destination

Test your new firewall configuration by from remote client execute command.

showmount -e 192.168.1.15

Configuration

After we have successfully configured the firewall, lets back to our server and configure NFS export directories. We start with creating a new directory, that we will exports.

mkdir /exports
chmod 777 /exports/

Now configure NFS to export it.

$ vi /etc/exports
/exports 192.168.1.0/24(rw,sync) 127.0.0.1(rw,sync)

To apply the new changes run

exportfs -r

And to list current exports

$ exportfs -v
/exports       192.168.1.0/24(rw,wdelay,root_squash,no_subtree_check)
/exports       127.0.0.1(rw,wdelay,root_squash,no_subtree_check)

Test

From a second machine on the same LAN, test connectivity to NFS server (192.168.1.15).

showmount -e 192.168.1.15

The simplest way to test read and write is to use the automounting functionality.

echo "Hello" >> /net/192.168.1.15/exports/foo.txt

April 21, 2014

How to Install Chrome on Ubuntu 14.04 LTS (Trusty)

Open a Terminal and run the commands.

Add the public key for the Google repo.

sudo wget -q -O - https://dl-ssl.google.com/linux/linux_signing_key.pub | sudo apt-key add -

Add the Google repo for the chome package.

sudo sh -c 'echo "deb http://dl.google.com/linux/chrome/deb/ stable main" >> /etc/apt/sources.list.d/google.list'

Update and install chrome web browser.

sudo apt-get update && sudo apt-get install google-chrome-stable

April 14, 2014

How To Configure KVM Virtual Machine Network

Background

Here I will configure a KVM host with virtual machines to be accessible from a local network.

This can be achieved in two ways by configure on KVM host machine:

A network bridge
Configure iptables as a router, which will forward traffic to virtual machines.

The easiest way is to use a network bridge, since then both desktop and virtual machines will be on the same subnet.

Prerequisite

Here we will configure the KVM host machine network configuration, manually, so we start by disable the NetworkManager

service NetworkManager stop
chkconfig NetworkManager off

KVM Host Network Bridge Configuration

/etc/sysconfig/network-scripts/ifcfg-eth0

DEVICE=eth0
TYPE=Ethernet
HWADDR=64:70:02:11:d9:83
NM_CONTROLLED=no
ONBOOT=yes
BRIDGE=br0

Above we have disabled NetworkManager (NM_CONTROLLED=no) and is using a Bridge.

/etc/sysconfig/network-scripts/ifcfg-br0

DEVICE=br0
TYPE=Bridge
ONBOOT=yes
DELAY=0
IPV6INIT=no
BOOTPROTO=none
IPADDR=192.168.1.10
NETMASK=255.255.255.0
GATEWAY=192.168.1.1
DNS1=192.168.1.1

Above have we configured a static IP (BOOTPROTO=none) and assigned IP, Gateway and DNS.

KVM Host iptables

Since we are not using the second alternative with routing, the KVM host machines iptables configuration is the same as default.

$ cat /etc/sysconfig/iptables

# Firewall configuration written by system-config-firewall
# Manual customization of this file is not recommended.
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
-A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
-A INPUT -p icmp -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -m state --state NEW -m tcp -p tcp --dport 22 -j ACCEPT
-A INPUT -j REJECT --reject-with icmp-host-prohibited
-A FORWARD -j REJECT --reject-with icmp-host-prohibited
COMMIT

After editing/creating files you might need to restore SELinux security contexts.

restorecon -RFv /etc/sysconfig/network-scripts/*

And finally restart network on KVM host

service network restart

Virtual Macines Network Configuration

The last part is to configure the virtual machine network. This is easiest achieved with the virt-manager.

For an existing virtual machine.

And for a new.

Inside the Virtual Machine

Inside the virtual machine you can configure either a static IP or a dynamic one. The easiest way is to use the tool system-config-network-tui.

Test

And finally test to ping the virtual machine (virtual1) from the desktop.

Reference

http://www.linux-kvm.org/page/Networking
/usr/share/doc/initscripts-*/sysconfig.txt

March 27, 2014

Fedora 20 Better Theme

The default theme (Adwaita) that Fedora 20 is shipped is not the best. And beside it has a large window border at the top of each window. A better theme that exists in default rpm repo is greybird. To install

yum install greybird-*

and to change use gnome-tweak-tool (rpm package gnome-tweak-tool)

March 26, 2014

Fedora 20 Install MySQL Server 5.5 and Workbench 6

MySQL Server 5.5

The MySQL packages has been renamed. The now official open source version of MySQL is MariaDB. To install the same version of MySQL on Fedora as in Enterprise Linux, such as RHEL, install these packages.

yum install community-mysql-server community-mysql-libs community-mysql

To start the mysqld.

service mysqld start

Set MySQL root password to 'root'.

mysqladmin -u root password root

Finally login and test password.

$ mysql -u root -p
Enter password: <root>

MySQL Workbench 6

The workbench rpm is orphan, so you need to download and install it manually. http://dev.mysql.com/downloads/tools/workbench/

$ rpm -pi /home/magnus/Downloads/mysql-workbench-community-6.0.9-1.fc20.x86_64.rpm 
error: Failed dependencies:
 libctemplate.so.2()(64bit) is needed by mysql-workbench-community-6.0.9-1.fc20.x86_64
 liblua-5.1.so()(64bit) is needed by mysql-workbench-community-6.0.9-1.fc20.x86_64
 libtinyxml.so.0()(64bit) is needed by mysql-workbench-community-6.0.9-1.fc20.x86_64
 libvsqlitepp.so.3()(64bit) is needed by mysql-workbench-community-6.0.9-1.fc20.x86_64
 libzip.so.2()(64bit) is needed by mysql-workbench-community-6.0.9-1.fc20.x86_64
 python-paramiko is needed by mysql-workbench-community-6.0.9-1.fc20.x86_64

Little bit of searching for installing dependeny packages, with 'yum provides', e.g.

yum provides "*/libctemplate.so.2"

And finally ending up with all required packages.

yum install -y ctemplate-devel compat-lua-libs tinyxml vsqlite++ libzip python-paramiko

Then run install of workbench again and start workbench and connect to you localhost.

Fedora 20 How to Install Eclipse

Before Eclipse started with bundling Eclipse into EE, C++, etc bundles. There were pain to install Eclipse and to get all it's plugins right. Then the bundles came. You download a zip file and unzipped and off you go.

But a better way is to have RPM packages of everything. And that is done with Fedora. (That is also done in Ubuntu, but they don't have any modern version of Eclipse available.)

To install Eclipse 4.3.1 (Kepler)

$ yum install eclipse-platform

Now you can search and install Eclipse plugin

$ yum search eclipse
...
eclipse-gef.noarch : Graphical Editing Framework (GEF) Eclipse plugin
eclipse-anyedit.noarch : AnyEdit plugin for eclipse
eclipse-avr.noarch : AVR Eclipse Plugin Sources
eclipse-cdt.x86_64 : Eclipse C/C++ Development Tools (CDT) plugin
eclipse-changelog.noarch : Eclipse ChangeLog plug-in
eclipse-checkstyle.noarch : Checkstyle plugin for Eclipse
eclipse-cmakeed.noarch : CMake Editor plug-in for Eclipse
eclipse-dltk.noarch : Dynamic Languages Toolkit (DLTK) Eclipse plugin
eclipse-dtp.noarch : Eclipse Data Tools Platform
eclipse-eclox.noarch : Eclipse-based doxygen plugin
eclipse-egit.noarch : Eclipse Git Integration
eclipse-egit-github.noarch : Eclipse EGit Mylyn GitHub Connector
eclipse-emf.noarch : Eclipse Modeling Framework (EMF) Eclipse plugin
eclipse-epic.noarch : Perl Eclipse plug-in
eclipse-fedorapackager.noarch : Fedora Packager for Eclipse
eclipse-findbugs.noarch : Eclipse plugin for FindBugs
eclipse-jbosstools.noarch : Eclipse plugins that support JBoss and related technology
eclipse-jgit.noarch : Eclipse JGit
eclipse-linuxtools.noarch : Linux specific Eclipse plugins
eclipse-m2e-core.noarch : Maven integration for Eclipse

$ yum install eclipse-gef eclipse-anyedit eclipse-changelog eclipse-checkstyle eclipse-dltk eclipse-dtp eclipse-egit eclipse-emf eclipse-fedorapackager eclipse-findbugs eclipse-jbosstools eclipse-m2e-core eclipse-subclipse

Fedora 20 Disable Gnome Alt+Tab from Grouping Windows

Most modern Linux distros (and including Windows) now days group window from the same application. I found this not effective and lowers mine productivity.

To disable grouping when Alt-Tab switching, install gnome extension https://extensions.gnome.org/extension/15/alternatetab/

March 20, 2014

Install and Configure KVM on Fedora 20

Install

$ yum groupinstall Virtialuzation

To manage the KVM daemon - libvirtd.

$ service libvirtd [status|start|stop|restart]

Imported directories.

Data - /var/lib/libvirt/
Configuration - /etc/libvirt/

Graphical manager, to install new virtual machines and control them.

$ virt-manager

Or the command line way.

$ virt-install --help

And to control the virtual machines, via command line.

$ virsh --help

March 16, 2014

HTTP Configure LDAP-Based Authentication

In my previous blog I showed you how to set up basic authentication via access file for a private directory. To do the same thing for LDAP, use this configuration instead.

LoadModule authnz_ldap_module modules/mod_authnz_ldap.so

LDAPTrustedGlobalCert CA_BASE64 /etc/httpd/example-ca.crt

<Directory "/private">
    AuthType Basic
    AuthName "Restricted Resource"
    AuthBasicProvider ldap
    AuthLDAPUrl "ldap://ldap.example.com/dc=example,dc=com" TLS
    Require valid-user
    Order deny,allow
    Deny from all
    Allow from all
</Directory>

Reference

http://httpd.apache.org/docs/2.2/mod/mod_authnz_ldap.html

HTTP Configure Private Directories

Create Private Directory

Here we will make things a little more difficult, we are going to create our new directory outside the apache default document root, which means, we will need to manually handle SELinux policy. We will get into detail how to do that soon, but first lets create our new private directory.

$ mkdir /private
$ echo "<h1>Hello Private</h1>" > /private/index.html

Set file permissions.

$ chown root:root -R /private 
$ chmod 755 /private
$ chmod 644 /private/index.html

Ok, here is where things get a little more complicated. Lets first have a look of the SELinux file context of the default document root.

$ ll -Zd /var/www/
drwxr-xr-x. root root system_u:object_r:httpd_sys_content_t:s0 /var/www/

$ ll -Zd /var/www/html/
drwxr-xr-x. root root system_u:object_r:httpd_sys_content_t:s0 /var/www/html/

$ ll -Z /var/www/html/index.html
-rw-r--r--. root root system_u:object_r:httpd_sys_content_t:s0 /var/www/html/index.html

Ok, now we knew how things should look like. Now lets look how things currently look in our new directory.

$ ll -Zd /private/
drwxr-xr-x. root root unconfined_u:object_r:default_t:s0 /private/

The thing you always should try first, is to try to restore default SELinux policy. Lets do that.

$ restorecon -RFv /private/

$ ll -Zd /private/
drwxr-xr-x. root root system_u:object_r:default_t:s0   /private/

$ ll -Z /private/index.html 
-rw-r--r--. root root system_u:object_r:default_t:s0   /private/index.html

Ok, so the last part that is missing is the file context. We can set that with semanage (policycoreutils-python package).

$ semanage fcontext -a -t httpd_sys_content_t '/private(/.*)?'

And to verify.

$ semanage fcontext -l | grep /private
/private(/.*)?                                     all files          system_u:object_r:httpd_sys_content_t:s0

Now we only need to restorecon on our new private directory.

$ restorecon -RFv /private
$ restorecon reset /private context system_u:object_r:default_t:s0->system_u:object_r:httpd_sys_content_t:s0
$ restorecon reset /private/index.html context system_u:object_r:default_t:s0->system_u:object_r:httpd_sys_content_t:s0

Configure Private Directory

Now lets begin to add our new private directory as public and test.

$ vi /etc/httpd/conf/httpd.conf
...
Alias /private/ "/private/"

<Directory "/private">
    Order deny,allow
    Deny from all
    Allow from all
</Directory>
...

Restart apache and test our new private directory. If things are not working go back and fix it.

Now we are going to add user authentication, but before that you might want to install apache manual.

$ yum install httpd-manual

We will here configure a basic authentication with file containing our user credential.

LoadModule authn_file_module modules/mod_authn_file.so

<Directory "/private">
    AuthType Basic
    AuthName "Restricted Resource"
    AuthUserFile /etc/httpd/.htpasswd
    Require valid-user
    Order deny,allow
    Deny from all
    Allow from all
</Directory>

To create the user credential

$ htpasswd -cm /etc/httpd/.htpasswd bob
New password: <redhat>
Re-type new password: <redhat>
Adding password for user bob

And now finally restart and test your new private directory.

Reference

http://httpd.apache.org/docs/2.2/mod/mod_authn_file.html

March 15, 2014

HTTP Deploy a Basic CGI Application

Prerequisite

You have successfully installed apache web server with default configuration.

Deploy

Copy our CGI script to default directory.

$ cat /var/www/cgi-bin/hello.cgi

#!/usr/bin/perl
print "Content-type: text/html\n\n";
print <<HTML;
<html>
<head>
<title>A Simple Perl CGI</title>
</head>
<body>
<h1>A Simple Perl CGI</h1>
<p>Hello World</p>
</body>
HTML
exit;

Set file permission

$ chown root:root /var/www/cgi-bin/hello.cgi
$ chmod 755 /var/www/cgi-bin/hello.cgi

Set SELinux

$ restorecon -RFv /var/www/cgi-bin/hello.cgi

Test

Open http://<your-host>/cgi-bin/hello.cgi

HTTP Configure a Virtual Host

Introduction

Virtual hosts are good when you want to server multiple web sites from the same web server.

Prerequisite

Install Apache Web Server.

$ yum install httpd

Since I do not have a reliable DNS, we need to hardcode the host name in /etc/hosts on the client.

$ cat /etc/hosts
...
192.168.122.20 jbossas1.magnuskkarlsson.com
192.168.122.20 virtualhost1.magnuskkarlsson.com

Initial Configuration

Configure Listen and ServerName, to be able to start the server clean without warnings.

$ egrep "Listen|ServerName" /etc/httpd/conf/httpd.conf
Listen 192.168.122.20:80
ServerName jbossas1.magnuskkarlsson.com:80

Also verify that firewall (iptables) is configured or stop it 'service iptables stop'.

$ iptables -vnL --line-numbers
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
num   pkts bytes target     prot opt in     out     source               destination         
...
5        0     0 ACCEPT     tcp  --  *      *       0.0.0.0/0            0.0.0.0/0           state NEW tcp dpt:443 
...
8        3   180 ACCEPT     tcp  --  *      *       0.0.0.0/0            0.0.0.0/0           state NEW tcp dpt:80 
...

Now check our installation by restarting apache web server and open url 'jbossas1.magnuskkarlsson.com' from client machine. You should be able to see Apache Welcome Page. If not go back and fix.

$ service httpd restart

Configure Name-Based Virtual Hosting

Now create two virtual host, one for the default host 'jbossas1.magnuskkarlsson.com' and one new 'virtualhost1.magnuskkarlsson.com'.

$ vi /etc/httpd/conf/httpd.conf 
...
NameVirtualHost 192.168.122.20:80

<VirtualHost 192.168.122.20:80>
    ServerName jbossas1.magnuskkarlsson.com
    ServerAdmin webmaster@jbossas1.magnuskkarlsson.com
    DocumentRoot /var/www/html
    ErrorLog logs/jbossas1.magnuskkarlsson.com-error_log
    CustomLog logs/jbossas1.magnuskkarlsson.com-access_log common
</VirtualHost>

<VirtualHost 192.168.122.20:80>
    ServerName virtualhost1.magnuskkarlsson.com
    ServerAdmin webmaster@dummy-host.example.com
    DocumentRoot /var/www/virtualhost1-magnuskkarlsson-com/html
    ErrorLog logs/virtualhost1.magnuskkarlsson.com-error_log
    CustomLog logs/virtualhost1.magnuskkarlsson.com-access_log common
</VirtualHost>

Now create the new document root for 'virtualhost1.magnuskkarlsson.com'.

$ mkdir -p /var/www/virtualhost1-magnuskkarlsson-com/html

Set file permissions.

$ chmod 755 /var/www/virtualhost1-magnuskkarlsson-com
$ chmod 755 /var/www/virtualhost1-magnuskkarlsson-com/html

Create test web page.

$ echo "Hello World" > /var/www/virtualhost1-magnuskkarlsson-com/html/index.html

Set SELinux for our new virtual host.

$ restorecon -RFv /var/www/

Test

Restart apache web server and test your new virtual host by accessing:

http://virtualhost1.magnuskkarlsson.com/ (you should see default apache web server welcome page)
http://jbossas1.magnuskkarlsson.com/ (you should see your 'Hello World' page)

Configure a System to Log to a Remote System.

Example forward all info message to remote host 192.168.122.10.

$ vi /etc/rsyslog.conf
...
$ModLoad imuxsock # provides support for local system logging (e.g. via logger command)
...
$WorkDirectory /var/lib/rsyslog # where to place spool files
$ActionQueueFileName fwdRule1 # unique name prefix for spool files
$ActionQueueMaxDiskSpace 1g   # 1gb space limit (use as much as possible)
$ActionQueueSaveOnShutdown on # save messages to disk on shutdown
$ActionQueueType LinkedList   # run asynchronously
$ActionResumeRetryCount -1    # infinite retries if host is down
*.info @192.168.122.10:514
...

Restart rsyslog to let changes take effects.

$ service rsyslog restart

And to test it use logger tool from client.

$ logger "Hello from client"

Open /var/log/messages on server and verify.

Reference

/usr/share/doc/rsyslog-*/rsyslog_conf.html

Configure a System to Accept Logging from a Remote System

UDP

Edit /etc/rsyslog.conf and enable module imudp.

$ vi /etc/rsyslog.conf
...
# Provides UDP syslog reception
$ModLoad imudp
$UDPServerRun 514
...

Restart rsyslog to let changes take effects.

$ service rsyslog restart

TCP

Edit /etc/rsyslog.conf and enable module imtcp.

$ vi /etc/rsyslog.conf
...
# Provides TCP syslog reception
$ModLoad imtcp
$InputTCPServerRun 514
...

Restart rsyslog to let changes take effects.

$ service rsyslog restart

Produce and Deliver Reports on System Utilization (Processor, Memory, Disk, and Network).

Processor

System Activity Reporter, SAR. To display 5 samples with 2 seconds apart.

$ sar -u 2 5
...
12:01:10 PM     CPU     %user     %nice   %system   %iowait    %steal     %idle
12:01:12 PM     all      1.25      0.00      0.69      0.06      0.00     98.00
12:01:14 PM     all      1.56      0.00      0.56      0.00      0.00     97.88
...

-u      Report  CPU  utilization.

Memory

vmstat - Report virtual memory statistics. To display 5 samples with 2 seconds apart.

$ vmstat 2 5
procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu-----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
 0  0      0 9898656 325956 1829612    0    0     1     5   10    8  1  0 99  0  0 
 0  0      0 9898136 325960 1829692    0    0     0    24  721 3252  1  0 99  0  0 
...

Disk

Report file system disk space usage.

$ df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/vg_rhel6-lv_root
                       77G   19G   55G  25% /
tmpfs                 7.8G  740K  7.8G   1% /dev/shm
/dev/sda1             485M   87M  374M  19% /boot
/dev/mapper/vg_rhel6-lv_home
                       49G  7.8G   38G  18% /home
/dev/sdf1             3.8G  246M  3.5G   7% /media/0526-3346

-h, --human-readable    Print sizes in human readable format (e.g., 1K 234M 2G)

Statistics for input/output statistics for devices, partitions and network filesystems (NFS). To display 5 samples with 2 seconds apart.

$ iostat -dNk 2 5
...
Device:            tps    kB_read/s    kB_wrtn/s    kB_read    kB_wrtn
sda               3.53         8.77        92.35    3226500   33970982
vg_rhel6-lv_root     4.70         8.63        22.48    3173286    8268420
vg_rhel6-lv_swap     0.00         0.00        55.68       1288   20479992
vg_rhel6-lv_home     3.55         0.13        14.20      48597    5222552
sdf               0.00         0.04         0.00      15962         11
...

-d     Display the device utilization report.
-N     Display the registered device mapper names for any device mapper devices.  
       Useful for viewing LVM2 statistics.
-k     Display statistics in kilobytes per second instead of blocks per second.  
       Data displayed are valid only with kernels 2.4 and later.

network

$ sar -n DEV
...
09:30:01 AM     IFACE   rxpck/s   txpck/s    rxkB/s    txkB/s   rxcmp/s   txcmp/s  rxmcst/s
09:40:01 AM        lo      0.00      0.00      0.00      0.00      0.00      0.00      0.00
09:40:01 AM      eth0      0.16      0.16      0.04      0.04      0.00      0.00      0.00
09:40:01 AM     wlan0      0.00      0.00      0.00      0.00      0.00      0.00      0.00
09:40:01 AM    virbr0      0.28      0.41      0.05      0.06      0.00      0.00      0.00
09:40:01 AM virbr0-nic      0.00      0.00      0.00      0.00      0.00      0.00      0.00
09:40:01 AM     vnet0      0.11      0.61      0.03      0.06      0.00      0.00      0.00
09:40:01 AM     vnet1      0.16      0.81      0.02      0.05      0.00      0.00      0.00
09:50:01 AM        lo      0.00      0.00      0.00      0.00      0.00      0.00      0.00
09:50:01 AM      eth0      0.09      0.11      0.03      0.02      0.00      0.00      0.00
09:50:01 AM     wlan0      0.00      0.00      0.00      0.00      0.00      0.00      0.00
09:50:01 AM    virbr0      1.35      2.18      1.26      0.19      0.00      0.00      0.00
09:50:01 AM virbr0-nic      0.00      0.00      0.00      0.00      0.00      0.00      0.00
...

Configure a System to Authenticate Using Kerberos

You can either do this graphically (system-config-authentication) or via command line (authconfig).

When doing it with the command line, it can be hard to remember all the parameter, but with help of '--help' it is easier.

The LDAP parameters

$ authconfig --help | grep ldap
  --enableldap          enable LDAP for user information by default
  --disableldap         disable LDAP for user information by default
  --enableldapauth      enable LDAP for authentication by default
  --disableldapauth     disable LDAP for authentication by default
  --ldapserver=<server>
  --ldapbasedn=<dn>     default LDAP base DN
  --enableldaptls, --enableldapstarttls
  --disableldaptls, --disableldapstarttls
  --ldaploadcacert=<URL>

The Kerberos parameter.

$ authconfig --help | grep krb
  --enablekrb5          enable kerberos authentication by default
  --disablekrb5         disable kerberos authentication by default
  --krb5kdc=<server>    default kerberos KDC
  --krb5adminserver=<server>
  --krb5realm=<realm>   default kerberos realm
  --enablekrb5kdcdns    enable use of DNS to find kerberos KDCs
  --disablekrb5kdcdns   disable use of DNS to find kerberos KDCs
  --enablekrb5realmdns  enable use of DNS to find kerberos realms
  --disablekrb5realmdns

And finally SSSD (System Security Services Daemon), which enable cached authentication, which in turn means enabled off-line authentication. Which both can be good and bad. An unstable network connection does not stop you for logging in. But you also need to remember that authentication data might be stale.

$ authconfig --help | grep sssd
  --enablesssd          enable SSSD for user information by default with
  --disablesssd         disable SSSD for user information by default (still
  --enablesssdauth      enable SSSD for authentication by default with
  --disablesssdauth     disable SSSD for authentication by default (still used

Lets put all this together and add --update at the end to update authentication configuration.

$ authconfig --enableldap --disableldapauth --ldapserver=<server> --ldapbasedn=<dn> --enableldaptls --ldaploadcacert=<URL> --enablekrb5 --krb5kdc=<server> --krb5adminserver=<server> --krb5realm=<realm> --enablesssd --enablesssdauth --update

March 14, 2014

SSH Port Forwarding

We have 3 machines.

Client (192.168.1.12)
JBoss (192.168.122.20)
Apache (192.168.122.10)

SSH Port Forwardning from localhost:5555 to 192.168.122.20:8080.

$ ssh -L 5555:192.168.122.20:8080 root@localhost

Now test your tunnel by opening a web browser from client and enter http://localhost:5555/. The tunnel is:

localhost:5555 -> 192.168.122.20:8080

Now lets tunnel through apache server (192.168.122.10:22) to jboss server (192.168.122.20:8080).

$ ssh -L 5555:192.168.122.20:8080 root@192.168.122.10

The tunnel is now:

localhost:5555 -> 192.168.122.10:22 -> 192.168.122.20:8080

So every tunneling begins at the client, that opens the tunnel.

Adding a Static Route to the Route Table

Prerequisite

Install the kernel documentation package, if you have not.

$ yum install kernel-doc -y

The package contains several documentation and you can list them all with 'rpm -ql kernel-doc'.

Display Current Routing

$ ip route show

Enabling Kernel Routing

To enable kernel paremeter ip_forward needs to be on.

$ sysctl -a | grep ip_forward
net.ipv4.ip_forward = 1

And the corresponding documentation.

$ less /usr/share/doc/kernel-doc-2.6.32/Documentation/networking/ip-sysctl.txt
...
ip_forward - BOOLEAN
        0 - disabled (default)
        not 0 - enabled

        Forward Packets between interfaces.

        This variable is special, its change resets all configuration
        parameters to their default state (RFC1122 for hosts, RFC1812
        for routers)
...

If you are not sure how to add search the system documentation.

$ find /usr/share/doc/ -name "*" | xargs grep -i "static route"
...
/usr/share/doc/initscripts-9.03.40/sysconfig.txt:  bring up static routes that depend on that device.  Calls
/usr/share/doc/initscripts-9.03.40/sysconfig.txt:  Set up static routes for a device.
...

$ less /usr/share/doc/initscripts-9.03.40/sysconfig.txt
...
/etc/sysconfig/network-scripts/route-<interface-name>

  Contains lines that specify additional routes that should be added when the
  associated interface is brought up.

  The files are processed by the ifup-routes script and uses the /sbin/ipcalc
  utility for all network masks and numbers. Routes are specified using the
  syntax:

    ADDRESSn=<network>
    NETMASKn=<network/prefix mask>
    GATEWAYn=<next-hop router/gateway IP address>

  The "n" is expected to be consecutive positive integers starting from 0.
  For example:

    ADDRESS0=192.168.2.0
    NETMASK0=255.255.255.0
    GATEWAY0=192.168.1.1

  adds a network route to the 192.168.2.0 network via the gateway at
  192.168.1.1. Since you must already have a route to the network of the
  gateway, there is no need to specify a device.

  Note: The ifup-routes script also supports an older syntax designed to be
  used directly as an argument to "/sbin/ip route add".
  If no "ADDRESSn" lines are found the following will still
  work:
  
  192.168.2.0/24 dev ppp0
  
  adds a network route to the 192.168.2.0 network through ppp0.
...

Or you can add via CLI, but this will not be permanent.

$ ip route add network/netmask via router_ip

Disable Ping Request (ICMP Echo) in Linux Kernel

Prerequisite

Install the kernel documentation package, if you have not.

$ yum install kernel-doc -y

The package contains several documentation and you can list them all with 'rpm -ql kernel-doc'.

Test Before

$ ping 192.168.122.10
PING 192.168.122.10 (192.168.122.10) 56(84) bytes of data.
64 bytes from 192.168.122.10: icmp_seq=1 ttl=64 time=0.171 ms

Ok. The machine is responding to ping.

Set Kernel Parameter to Ignore Ping (ICMP echo) Request

Now use kernel configuration tool, sysctl, to first list all parameter that contain ICMP.

$ sysctl -a | grep icmp
net.netfilter.nf_conntrack_icmpv6_timeout = 30
net.netfilter.nf_conntrack_icmp_timeout = 30
net.ipv4.icmp_echo_ignore_all = 0
net.ipv4.icmp_echo_ignore_broadcasts = 1
net.ipv4.icmp_ignore_bogus_error_responses = 1
net.ipv4.icmp_errors_use_inbound_ifaddr = 0
net.ipv4.icmp_ratelimit = 1000
net.ipv4.icmp_ratemask = 6168
net.ipv6.icmp.ratelimit = 1000

To find out what each parameter do read the kernel network ip sysctl documentation.

$ grep -A5 icmp /usr/share/doc/kernel-doc-*/Documentation/networking/ip-sysctl.txt 
icmp_echo_ignore_all - BOOLEAN
 If set non-zero, then the kernel will ignore all ICMP ECHO
 requests sent to it.
 Default: 0
...

And to set kernel parameter.

$ sysctl -w net.ipv4.icmp_echo_ignore_all=1

Now test again to ping server and you should not get any respond.

To make the changes permanent.

$ echo "net.ipv4.icmp_echo_ignore_all = 1" >> /etc/sysctl.conf

Network Bonding in RHEL 6

Introduction

To bind multiple network interfaces together into a single channel is called bonding.

The reason for this is to achieve:

Round robin around network interfaces.
Master - slave for redundancy.
Throughput. Use all at the same time.

Reference

RHEL 6 Deployment Guide

IP Aliases in RHEL 6

Introduction

Assigning multiple IP addresses to a single interface is called IP aliasing. This can be handy if you want a single web server to serve multiple sites.

Prerequisite

It is advised to disable NetworkManager.

$ service NetworkManager stop; chkconfig NetworkManager off

Configuration

Show current configuration for eth0.

$ ip addr show eth0
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 52:54:00:22:d1:df brd ff:ff:ff:ff:ff:ff
    inet 192.168.122.20/24 brd 192.168.122.255 scope global eth0
    inet6 fe80::5054:ff:fe22:d1df/64 scope link 
       valid_lft forever preferred_lft forever

Add IP alias.

$ ip addr add 192.168.122.250/24 dev eth0 label eth0:0

Show new configuration for eth0

$ ip addr show eth0
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 52:54:00:22:d1:df brd ff:ff:ff:ff:ff:ff
    inet 192.168.122.20/24 brd 192.168.122.255 scope global eth0
    inet 192.168.122.250/24 scope global eth0:0
    inet6 fe80::5054:ff:fe22:d1df/64 scope link 
       valid_lft forever preferred_lft forever

To make it persistent edit the following

$ vi /etc/sysconfig/network-scripts/ifcfg-eth0:0
DEVICE=eth0:0
IPADDR=192.168.122.250
PREFIX=24
ONPARENT=yes

Now restart network service.

$ service network restart

Test

Ping from another machine

$ ping 192.168.122.250
PING 192.168.122.250 (192.168.122.250) 56(84) bytes of data.
64 bytes from 192.168.122.250: icmp_seq=1 ttl=64 time=1.05 ms

Reference

/usr/share/doc/initscripts-*/sysconfig.txt

March 13, 2014

Build a Simple RPM Package

Prerequisite

Install package that contain the rpmbuild tool that create the rpm package.

$ yum install rpm-build

Install also a convenient development tool for setting up environment.

$ yum install rpmdevtools

When building rpm package you should do that with a noon root user. To create a new user.

$ useradd rpmuser

Setup

Change to rpm user and from it's home directory run:

$ rpmdev-setuptree

This will create a new empty catalogue structure for your rpm package development.

Creating the Program

$ vi ~/rpmbuild/SOURCES/hello.sh

#!/bin/bash
echo "Good morning, world."

We can test run to see that it actually runs.

$ chmod +x ~/rpmbuild/SOURCES/hello.sh
$ ~/rpmbuild/SOURCES/hello.sh
Good morning, world.

Creating the RPM Spec File

Now with help of wim, that will create a template spec file, we will create a rpm spec file for our hello rpm package.

$ vim ~/rpmbuild/SPECS/hello.spec
Name:   hello  
Version: 1.0 
Release: 1%{?dist}
Summary:  A simple hello world application. 

Group:  Applications/File
License: GPLv2+
URL:  http://magnus-k-karlsson.blogspot.se/  
Source0: hello.sh 
BuildRoot: %(mktemp -ud %{_tmppath}/%{name}-%{version}-%{release}-XXXXXX)

#BuildRequires: 
Requires: bash

%description

# Prep is used to set up the environment for building the rpm package
# Expansion of source tar balls are done in this section
#%prep
#%setup -q

# Used to compile and to build the source
#%build
#%configure
#make %{?_smp_mflags}

# The installation.
%install
rm -rf %{buildroot}
#make install DESTDIR=%{buildroot}
mkdir -p %{buildroot}/usr/bin
cp %{SOURCE0} $RPM_BUILD_ROOT/usr/bin/.

%clean
rm -rf %{buildroot}

%files
%defattr(-,root,root,-)
/usr/bin/hello.sh
%doc

%changelog

Build the RPM

$ rpmbuild -ba ~/rpmbuild/SPECS/hello.spec

Test the RPM

Query (q) the local package (p) for all it's files (l).

$ rpm -qpl rpmbuild/RPMS/x86_64/hello-1.0-1.el6.x86_64.rpm
/usr/bin/hello.sh

Now switch to root and install the package.

$ rpm -pi /home/rpmuser/rpmbuild/RPMS/x86_64/hello-1.0-1.el6.x86_64.rpm

And test it.

$ hello.sh 
Good morning, world.

And to uninstall it.

$ yum erase hello
...

Yum Plugins

There are numerous yum plugins. You can search for which are available.

$ yum search yum-plugin
...
PackageKit-yum-plugin.x86_64 : Tell PackageKit to check for updates when yum exits
anaconda-yum-plugins.noarch : Installation-related yum plugins
kabi-yum-plugins.noarch : The Red Hat Enterprise Linux kernel ABI yum plugin
yum-plugin-aliases.noarch : Yum plugin to enable aliases filters
yum-plugin-changelog.noarch : Yum plugin for viewing package changelogs before/after updating
yum-plugin-downloadonly.noarch : Yum plugin to add downloadonly command option
yum-plugin-protect-packages.noarch : Yum plugin to prevents Yum from removing itself and other protected packages
yum-plugin-security.noarch : Yum plugin to enable security filters
yum-plugin-tmprepo.noarch : Yum plugin to add temporary repositories
yum-plugin-verify.noarch : Yum plugin to add verify command, and options
yum-plugin-versionlock.noarch : Yum plugin to lock specified packages from being updated

What does yum-plugin-verify do?

"This plugin adds the commands verify, verify-all and verify-rpm. There are also a couple of options. This command works like rpm -V, to verify your installation." [yum info yum-plugin-verify]

For more information about each commands, run 'yum --help'

What does yum-plugin-versionlock do?

"This plugin takes a set of name/versions for packages and excludes all other versions of those packages (including optionally following obsoletes). This allows you to protect packages from being updated by newer versions, for example." [yum info yum-plugin-versionlock]

The yum-plugin-versionlock uses the /etc/yum/pluginconf.d/versionlock.list to lock down specific packages.

The following format is used for locking down. See /usr/share/doc/yum-plugin-versionlock-*/README.

EPOCH:NAME-VERSION-RELEASE.ARCH

Encrypting Files with GnuPG

Generate private key.

$ gpg --gen-key

List all public keys.

$ gpg --list-keys

Export a public key.

$ gpg --armor --output "magnus.k.karlsson.txt.asc" --export "Magnus K Karlsson"

Import a public key from "Pelle Petterson".

$ gpg --import pelle.petterson.txt.asc

Encrypt a file for recipient "Pelle Petterson", with public key from "Pelle Petterson".

$ gpg --armor --recipient "Pelle Petterson" --output "foo.txt.gpg" --encrypt "foo.txt"

Decrypt a file, encrypted with your public key.

$ gpg --output "foo.txt" --decrypt "foo.txt.gpg"

Using OpenLDAP as Authentication Directory Service in RHEL 6

Installing OpenLDAP

$ yum install -y openldap openldap-clients openldap-servers

Configure OpenLDAP

Modify domain (olcSuffix) and the LDAP super username (olcRootDN).

$ egrep "Suffix|Root" olcDatabase\=\{2\}bdb.ldif 
olcSuffix: dc=example,dc=com
olcRootDN: cn=admin,dc=example,dc=com

Set password for the LDAP super user. To create password use slappasswd.

$ slappasswd 
New password: <redhat>
Re-enter new password: <redhat>
{SSHA}VG9HSAjxn19Qb3+gveyC2H5DlFRMIACD

And add password to configuration file.

$ grep olcRootPW /etc/openldap/slapd.d/cn\=config/olcDatabase\=\{2\}bdb.ldif
olcRootPW: {SSHA}0aIvJ8mtnCYGqDc5YhW2C9rRLJwWv/HX

Create OpenLDAP Schema

Creat an empty text file /root/example.com.ldif, with

$ service slapd start

Configure OpenLDAP

# Root entry
dn: dc=example,dc=com
objectclass: dcObject
objectclass: organization
o: Example Company
dc: example

# Admin DN
dn: cn=admin,dc=example,dc=com
objectclass: organizationalRole
cn: admin

# Base DN for users
dn: ou=users,dc=example,dc=com
changetype: add
objectclass: top
objectclass: organizationalUnit
ou: users

# Base DN for groups
dn: ou=groups,dc=example,dc=com
changetype: add
objectclass: top
objectclass: organizationalUnit
ou: groups

Add this.

$ ldapadd -x -D "cn=admin,dc=example,dc=com" -W -f /root/example.com.ldif 
Enter LDAP Password: <redhat>
adding new entry "dc=example,dc=com"

adding new entry "cn=admin,dc=example,dc=com"

adding new entry "ou=users,dc=example,dc=com"

adding new entry "ou=groups,dc=example,dc=com"

Verify add with search.

$ ldapsearch -x -b 'dc=example,dc=com'

Add User and Group OpenLDAP

# cat student.passwd.ldif
dn: uid=student,ou=users,dc=example,dc=com
uid: student
cn: student
objectClass: account
objectClass: posixAccount
objectClass: top
objectClass: shadowAccount
userPassword: {crypt}!!
shadowLastChange: 16128
shadowMin: 0
shadowMax: 99999
shadowWarning: 7
shadowExpire: 15770
loginShell: /bin/bash
uidNumber: 501
gidNumber: 501
homeDirectory: /home/student

$ ldapadd -x -D "cn=admin,dc=example,dc=com" -W -f student.passwd.ldif 
Enter LDAP Password: 
adding new entry "uid=student,ou=users,dc=example,dc=com"

# cat student.group.ldif 
dn: cn=student,ou=groups,dc=example,dc=com
objectClass: posixGroup
objectClass: top
cn: student
userPassword: {crypt}x
gidNumber: 501

$ ldapadd -x -D "cn=admin,dc=example,dc=com" -W -f student.group.ldif 
Enter LDAP Password: 
adding new entry "cn=student,ou=groups,dc=example,dc=com"

Configure Client Authentication through LDAP

$ yum install openldap-clients

You can configure this graphically

or you can do it via command line tool authconfig.

$ authconfig --enableldap --enableldapauth --ldapserver=192.168.122.10 --ldapbasedn="dc=example,dc=com" --disableldaptls --update
Starting sssd:                                             [  OK

Test

$ getent passwd student
student:*:501:501:student:/home/student:/bin/bash

Reference

March 12, 2014

Blogspot Blogger set Dynamic Width

It is quite silly with fix width layout for HTML pages, which indirectly means a web page will only use a small part of modern laptop or monitors screen. Why not make it dynamic? Let people self decide their size, by simply resizing theirs browser window. Static width does not make sense for me. So this is how I changed this blog. Simple and safe http://thewebthought.blogspot.com/2011/09/blogger-make-your-blog-fluid-fit-any.html.

How to Disable System Beep in Fedora 20

The default setup of Fedora 20 have a quite annoying feature and that is the system beep. The beep sounds when using auto completion in terminal window, but also in firefox when searching in page and not results are found.

To disable Terminal beep.

$ xset b off

To disable Firefox beep, when no search result are found in page.

about:config
accessibility.typeaheadfind.enablesound

March 11, 2014

Installing RHEL 6 Default Directory Servers, OpenLDAP

Introduction

In this blog I will show you how to install, configure and test the default directory service in RHEL 6 - OpenLDAP. LDAP directory services are common used for storing authentication credential.

1. Install

$ yum install -y openldap openldap-clients openldap-servers

2. Configure

The OpenLDAP configuration has been altered in RHEL 6. Previously it was a configuration file /etc/openldap/slapd.conf, but now it is a configuration database located in /etc/openldap/slapd.d/.

Global configuration is stored in /etc/openldap/slapd.d/cn\=config.ldif.

$ cat /etc/openldap/slapd.d/cn\=config.ldif
dn: cn=config
objectClass: olcGlobal
cn: config
olcConfigFile: /etc/openldap/slapd.conf.bak
olcConfigDir: /etc/openldap/slapd.d
olcAllows: bind_v2
olcArgsFile: /var/run/openldap/slapd.args
...

Database specific configuration is stored in /etc/openldap/slapd.d/cn\=config/olcDatabase\=\{2\}bdb.ldif.

We will here change the olcSuffix (the domain for which the LDAP server provides information) and the olcRootDN (the LDAP super username).

$ grep olcSuffix /etc/openldap/slapd.d/cn\=config/olcDatabase\=\{2\}bdb.ldif
olcSuffix: dc=magnuskkarlsson,dc=com

$ grep olcRootDN /etc/openldap/slapd.d/cn\=config/olcDatabase\=\{2\}bdb.ldif
olcRootDN: cn=Manager,dc=magnuskkarlsson,dc=com

Finally we need to generate a password for olcRootDN. To generate the password we use the slappasswd tool. And to add it, we add the directive olcRootPW to the /etc/openldap/slapd.d/cn\=config/olcDatabase\=\{2\}bdb.ldif.

$ slappasswd 
New password: <redhat>
Re-enter new password: <redhat>
{SSHA}0aIvJ8mtnCYGqDc5YhW2C9rRLJwWv/HX

$ grep olcRootPW /etc/openldap/slapd.d/cn\=config/olcDatabase\=\{2\}bdb.ldif
olcRootPW: {SSHA}0aIvJ8mtnCYGqDc5YhW2C9rRLJwWv/HX

3. Start

$ service slapd start

And to automatically start OpenLDAP at boot time.

$ chkconfig slapd on

4. Test

To test the installation we perform a simple search (query for you SQL people).

$ ldapsearch -x -b '' -s base '(objectclass=*)' namingContexts
...
dn:
namingContexts: dc=magnuskkarlsson,dc=com
...

Now we are going to add entries to your directory. To add entries we use the ldapadd tool. The ldapadd expects LDIF (LDAP Data Interchange Format) file.

$ cat /tmp/example.ldif
dn: dc=magnuskkarlsson,dc=com
objectclass: dcObject
objectclass: organization
o: Magnus K Karlsson AB
dc: magnuskkarlsson

dn: cn=Manager,dc=magnuskkarlsson,dc=com
objectclass: organizationalRole
cn: Manager

$ ldapadd -x -D "cn=Manager,dc=magnuskkarlsson,dc=com" -W -f /tmp/example.ldif
Enter LDAP Password: <redhat>
adding new entry "dc=magnuskkarlsson,dc=com"

adding new entry "cn=Manager,dc=magnuskkarlsson,dc=com"

Finally we test the added entries.

$ ldapsearch -x -b 'dc=magnuskkarlsson,dc=com' '(objectclass=*)'
...
# magnuskkarlsson.com
dn: dc=magnuskkarlsson,dc=com
objectClass: dcObject
objectClass: organization
o: Magnus K Karlsson AB
dc: magnuskkarlsson

# Manager, magnuskkarlsson.com
dn: cn=Manager,dc=magnuskkarlsson,dc=com
objectClass: organizationalRole
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February 20, 2014

Automatic RHEL 6 Installation with Kickstart

Introduction

Today the requirement are higher to quicker responds to the market. For a computer operation that means, they must be quicker to bring up new machine. The Red Hat solution for this is to use kickstart to standardize and automate the installation of a new RHEL instances.

The simplest way to create a working kickstart file is to actually install a new system (the way you want) and then use the kickstart created by anaconda to install new machine with.

The more advanced way is to start from scratch and use the system-config-kickstart tool and create you kickstart file. But there are some shortcoming with this tool and that is it can not handle LVM.

The pragmatic way is to start from a anaconda generated kickstart file and then edit with system-config-kickstart and finally manually add the LVM partition.

Here I will show you the easy way and use the anaconda generated file.

Prerequisite

Lets get started and install a new RHEL instance the manually way. We will install this machine as a virtualized machine and as hypervisor we will use KVM.

The requirement for this machine are:

8 GB Disk Space
Basic Storage Devices
Use All Space

We will select the last checkbox 'Review and modify...', so we can see what is actually done.

What we see above is that two primary partitions are created - vda1 and vda2.

vda1 will contain standard ext4 file system for boot. The size of 500 MB is good for boot partition and should rarely be changed.
vda2 will be formatted with LVM and will fill up the rest of the available disk. This is also good.

The next step is the logical volumes: lv_root and lv_swap.

Note the few partition that are here created. For a server installation you would probably create more partitions, e.g. a separate partition for /var/log directory for a production server and for desktop installation you would probably create a separate partition for /home. But here we will keep to the basic suggested partition layout.

The second thing that is noteworthy is the small swap space. The thumb rule for a minimal installation production server is:

< 2GB RAM, use 2 * RAM
>= 2GB RAM, use RAM + 2GB

But remember these are not hard rules and dependce how often you will restart you system. For a desktop installation you will get away with smaller swap space.

Finally we will select to install a minimal installation. When installation is finish we will end up with a anaconda generated kickstart file located in /root/anaconda-ks.cfg.

Kickstart file

To make this kickstart file automatic we need to do three things:

Uncomment the LVM partitioning. I also renamed the volume group to vg_rhel6.
Add zerombr, to answer yes to the prompt question that all existing partitions will be destroyed.
And finally automatically restart the system after installation.

# Kickstart file automatically generated by anaconda.

#version=DEVEL
install
cdrom
lang en_US.UTF-8
keyboard sv-latin1
network --onboot yes --device eth0 --bootproto dhcp --noipv6
rootpw  --iscrypted $6$...$...
firewall --service=ssh
authconfig --enableshadow --passalgo=sha512
selinux --enforcing
timezone --utc Europe/Stockholm
bootloader --location=mbr --driveorder=vda --append="crashkernel=auto rhgb quiet"
# The following is the partition information you requested
# Note that any partitions you deleted are not expressed
# here so unless you clear all partitions first, this is
# not guaranteed to work
zerombr
clearpart --all --drives=vda --initlabel

part /boot --fstype=ext4 --size=500
part pv.253002 --grow --size=1
volgroup vg_rhel6 --pesize=4096 pv.253002
logvol / --fstype=ext4 --name=lv_root --vgname=vg_rhel6 --grow --size=1024 --maxsize=51200
logvol swap --name=lv_swap --vgname=vg_rhel6 --grow --size=819 --maxsize=819

reboot

%packages
@core
@server-policy
%end

Test

The last step is to test it. First we need to make it accessible during installation. The easiest way to do that, is to use either a FTP or HTTP server. There are also other ways, such as using a shared network disk, accessible via NFS or CIFS. But I would recommend using a known FTP server.

Now start a new RHEL installation. At the first menu, press TAB.

Then at the end enter 'ks=ftp://<server>/<path>' and press ENTER.

Reference

Starting a Kickstart Installation - https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Installation_Guide/s1-kickstart2-startinginstall.html
Kickstart Options - https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Installation_Guide/s1-kickstart2-options.html