Eu olho pela janela

Eu olho pela janela
Vejo o ceu escuro
As estrelas sapiscam o ceu
Parecem manchas no escuro veludo
sao tao pequenas
Tao distantes
Brilham
Num ceu escuro e intrigante
Quando eu olho pro ceu
Eu penso no meu passado
Parece tao distante
Mas tao presente
Memorias
Cheiros
Cores
Fotos tiradas pelos meus olhos
Eu olho pela janela
Vejo o ceu
Pensamentos correm pela cabeca
Onde eu estou
Porque estou aqui
Quando sera que vou partir?
Nada faz sentido
Tudo se move rapido
Num constante agito
As estrelas gritam a luz
O ceu grita a escuridao
a Noite pede calma
pessoas passam pelas ruas
Acordam o silencio
mes pensamentos nunca dormem
estao sempre a passsear
correm e saltam pela minha memoria
sera que eu existo
como foi que eu vim parar aqui?
Sera que eu nao sou so um pensamento?
Eu olho pela janela
Ja nao vejo as estrelas
O ceu ta escuro e nublado
Uma neblina fina
Que cobre tudo devagar
Eu ja nao pensao mais
Talvez ja nem sinta
as horas passam
e nada muda
tudo muda,
Sera que eu nao percebi?
Nem vejo mais estrelas,
Nem sei se olho mais pela janela
Sera que a janela existe?
Sera que nao e tudo um sonho
ou um pesadelo
Atormentado
a procura de uma janela
por onde eu vejo
um ceu estrelado
que me acalma e da tranquilidade
O que e tranquilidade?

by Renato de Oliveira

Fim de Tarde

Fim de tarde
A luz comeca a morrer
Todas as cores se suavisam
Num tom tranquilo de pastel
O ceu vai se alaranjando
O sol devagar vai se escondendo
No horizonte suavizado de rosa
A lua vai despontando
Devagar vai surgindo
O dia vai escurecendo
Os passaros ainda cantam
Num tom meio melancolico
Como se sentissem saudades
Do dia que diz adeus
Sao tantas cores suaves
De um fim de tarde
que comeca a morrer
Morre a luz tristemente
No horizonte melado de rosa
Morre os cantos dos passaros
Que se agasalham nos seus ninhos
Tudo vai ficando devagar
Se preparando pra dormir
As estrelas comecam a pontilhar
e o dia vai morrendo
as cores desaparecendo
tudo vai escurecendo
o fim de tarde
vai acordando a noite
e a noite vai cobrindo o dia
e tanta magia
tanta beleza
Tanta tranquilidade
que nos da a natureza
um magestoso fim de tarde
Coberto de alegria e tristeza

by Renato de Oliveira

How to Install and configure Apache on Red Hat/Centos 6.x

How to Install and configure Apache on Red Hat/Centos 6.x

Apache is the most used web server on the Internet. It is reliable, fast, easy to set up, relatively secure and the Apache Foundation is on top of patches.

I thought you might want to see how easy and nice it is to work with it, so I decided to write a post.

I’ll show you how to get it installed, configured and set up a Name Based Virtual Host.

Packages Dependencies

·         httpd.x86_64

·         apr.x86_64                                   

·         apr-util.x86_64                                                      

·         apr-util-ldap.x86_64

·         httpd-tools.x86_64                      

·         mailcap.noarch

Install all packages

[root@centos63 dhcp]# yum install httpd.x86_64 apr.x86_64 apr-util.x86_64 apr-util-ldap.x86_64 httpd-tools.x86_64 mailcap.noarch –y

Once all the packages above have been installed, we can start configuring Apache.

Apache Configuration File

Apache main configuration files, reside on /etc/httpd/conf.

On Red Hat based distributions, Apache is named ‘httpd’, and its configuration files are located on /etc/httpd, its logs are stored on /var/log/httpd and the actual content or the root directory is located on /var/www/html.

Let’s explore it

[root@centos63 dhcp]# cd /etc/httpd/conf

[root@centos63 conf]# ls -l

-rw-r--r-- 1 root root 34418 Dec  5 08:59 httpd.conf

[root@centos63 conf]# vi httpd.conf

 

Note: Apache config file is very extensive; it has directives for many things. I’ll show you how to get it up and running quickly. I’ll show you more complex things on other posts i.e. mod proxy and mod rewrite which are quite useful, I think.

 

Directives to set

Email

ServerAdmin root@localhost

Change it to your email address, for example:

ServerAdmin linux-up@ntlworld.com

Server Name

#ServerName www.example.com:80

Uncomment the line above and change it to your Server’s name. For example:

ServerName www.renpippa.co.uk

That is how easy it is to get it up and running.

Setting up a virtual host

If you have multiple websites being hosted on the same server and the server only has a single public IP address, virtual hosts will help you immensely. This is also called ‘Named-Based Virtual Hosts’

 

[root@centos63]# cd /etc

[root@centos63 etc]# vi /etc/hosts
192.168.1.34  centos63 centos63.adlinux.int www.centos63.co.uk www.renpippa.co.uk

[root@centos63]# mkdir /var/www/www.centos63.co.uk

[root@centos63]# touch /var/www/www.centos63.co.uk/index.html

[root@centos63]# echo “Welcome to WWW.CENTOS63.CO.UK”
> /var/www/www.centos63.co.uk/index.html

Note: Replace the names above with your Virtual Hosts Names, the name of the domains you with to host.

[root@centos63 conf]# vi /etc/httpd/conf/httpd.conf

Add the lines below to the bottom of the httpd.conf file, save and quit.

# Virtual Hosts Configuration

NameVirtualHost *:80

<VirtualHost *:80>

    ServerAdmin webmaster@www.centos63.co.uk
    DocumentRoot /var/www/www.centos63.co.uk
    ServerName www.centos63.co.uk
    ErrorLog logs/www.centos63.co.uk-error_log
    CustomLog logs/www.centos63.co.uk-access_log common
</VirtualHost>

Restart Apache

[root@centos63]# service httpd restart

Open your browser and test teh configuration. If you are using a different PC, you need to add the Domain name to your DNS, or edit your hosts file. If your PC is Linux, all you need is to edit /etc/hosts. If your PC is Windows based, you need to edit c:\windows\system32\drivers\etc\hosts.

 

I hope you enjoy it.

 

By Renato de Oliveira

How to Setup a DHCP Server on Red Hat/Centos 6.x

How to Setup a DHCP Server on Red Hat/Centos 6.x

DHCP stands for (Host Configuration Protocol). It is used to assign IP addresses automatically at boot time to network clients.

There are basically two ways of assigning IPs to Hosts or devices on any given network; manually or by using an automated method (DHCP Server).

This is my opinion based on past experience.

I think if your network is relatively small, between 10-50 hosts/devices, I would recommend using static IPs instead of a DHCP server. There are pros and cons in doing so.

For example if you need resiliency for your network you will need to start to think about redundancy for your DHCP server. There are options, but things start to become unnecessary complex. I know some sys admins; they use DHCP for everything, including servers. I just think it is not a good idea.

Package requirement

      ·         dhcp.x86_64
      ·         dhcp-common.x86_64

Installing packages

[root@centos63 ~]# yum install dhcp.x86_64 dhcp-common.x86_64 –y

Start-up DHCP service at boot time

[root@centos63 ~]# chkconfig --level 2345 dhcpd on
 
Use the sample configuration to start with

[root@centos63 ~]# vi /etc/dhcp/dhcpd.conf

Note: Copy and paste the lines below:

# Sample DHCP generated by Renato de Oliveira

# http://ukaying.blogspot.co.uk
# option definitions (Domain Name)
option domain-name "adlinux.int";

# Lease time and expiration

default-lease-time 600;
max-lease-time 7200;

# If this DHCP server is the official DHCP server for the local

# network, the authoritative directive should be uncommented.
authoritative;

# Use this to send dhcp log messages to a different log file (you also

# have to hack syslog.conf to complete the redirection).
log-facility local7;

# DHCP netwok and mask decalaration

subnet 192.168.1.0 netmask 255.255.255.0 {
  range 192.168.1.100 192.168.1.160;
  option routers 192.168.1.1;
  option domain-name-servers "192.168.1.22";
  option domain-name "adlinux.int";
}

# Fixed IP addresses can also be specified for hosts.  

host linadws01 {
  hardware ethernet 00:0c:29:eb:dc:90;
  fixed-address 192.168.1.160;
}

Note: Make sure you change this file to suit your needs. For example, remember to change Domain Name, IP Addresses, and Name Servers etc.

Start the DHCP Server Service

[root@centos63 ~]# service dhcpd start

Note: If the service fails to start, check /var/log/messages, it will give you a very good idea on what is wrong. Most the time it is syntax or typos.

Testing

On another Linux Server, change the file /etc/sysconfig/network-scripts/ifcfg-eth0 to use DHCP, see below:

[root@centos63 ~]# vi /etc/sysconfig/network-scripts/ifcfg-eth0

DEVICE=”eth0”

BOOTPROTO=dhcp
ONBOOT=yes

Reboot the Client

 

Watch the logs on the server

[root@centos63 ~]# tail –f /var/log/messages

You should see an output similar to the one below:

Apr 14 17:26:44 centos63 dhcpd: DHCPDISCOVER from 00:0c:29:eb:dc:90 via eth0

Apr 14 17:26:44 centos63 dhcpd: DHCPOFFER on 192.168.1.160 to 00:0c:29:eb:dc:90 via eth0
Apr 14 17:26:44 centos63 dhcpd: Dynamic and static leases present for 192.168.1.160.
Apr 14 17:26:44 centos63 dhcpd: Remove host declaration linadws01 or remove 192.168.1.160
Apr 14 17:26:44 centos63 dhcpd: from the dynamic address pool for 192.168.1.0/24
Apr 14 17:26:44 centos63 dhcpd: DHCPREQUEST for 192.168.1.160 (192.168.1.34) from 00:0c:29:eb:dc:90 via eth0
Apr 14 17:26:44 centos63 dhcpd: DHCPACK on 192.168.1.160 to 00:0c:29:eb:dc:90 via eth0

Still on the client, check:

 1.    Its IP address

[root@centos63 ~]# ifconfig

2.    Check its default gateway

[root@centos63 ~]# route –n

3.  Check the /etc/resolv.conf

[root@centos63 ~]#cat /etc/resolv.conf
; generated by /sbin/dhcpclient-script
search adlinux.int
nameserver 192.168.1.22

If you can confirm the results above, then you have successfully setup a DHCP server for your network. If you have problems, just keep an eye on /var/log/messages.

Hope you enjoyed this post.

By Renato de Oliveira  

How to set up an NFS server (Red Hat/Centos 6.x)

How to Install NFS Server on Red Hat/Centos 6.x

NFS stands for (Network File System) it is a mechanism used by UNIX like hosts to share files across networks. There are two versions mostly used NVFv3 and NFSv4 – there are many differences between both. I am not going to cover them.

NFS used to be dependent on a service called portmap and used port 111, which was a bit flaky. NFS is much more reliable and faster than it used to be; we can run it over TCP and across firewalls. I am not going to demonstrate it on this post.

I am not going to go over discussions about security, and how to lock down your NFS server, or open iptables ports. I assume your iptables will be off. Security is a very complex and deep subject. My intention is only to give you the knowledge to set up an NFS quickly and start using it.

Perhaps I’ll write another post on how to secure your NFS server.

Packages requirement

·         nfs

·         nfslock

·         rpcbind

The following RPC processes facilitate NFS services:

·         rpc.mountd

·         rpc.nfsd

·         lockd

·         rpc.statd

·         rpc.rquotad

·         rpc.idmapd

Installing Packages

·         nfs-utils.x86_64

·         nfs-utils-lib.x86_64

·         rpcbind.x86_64

[root@centos63 ~]# yum install nfs-utils.x86_64 nfs-utils-lib.x86_64 rpcbind.x86_64 –y

Services to start at boot time

You need to make sure some important services are running.

 

[root@centos63 ~]# chkconfig --level 2345 rpcbind on

[root@centos63 ~]# chkconfig --level 2345 nfs on

[root@centos63 ~]# service rpcbind start

[root@centos63 ~]# service nfs start

 

Setting up the NFS export

[root@centos63 ~]# mkdir /nfs

[root@centos63 ~]# vi /etc/exports   

 

Add the line below, save and quite the file

/nfs    *(rw)

 

Note: The line about means - export /nfs folder to any client with read and write permissions.

I advise locking it down a bit and export it to your subnet, or single IPs.

[root@centos63 ~]# exportfs –a

[root@centos63 ~]# exportfs

/nfs            <world>

Note: The above command will export your folder configuration.

 

Let’s test it?!

[root@centos63 ~]# mount -t nfs localhost:nfs /media/

[root@centos63 ~]# df -h

Filesystem            Size  Used Avail Use% Mounted on

/dev/mapper/VolGroup-lv_root

                       47G  1.2G   44G   3% /

tmpfs                 499M     0  499M   0% /dev/shm

/dev/sda1             485M   73M  387M  16% /boot

localhost:nfs          47G  1.2G   44G   3% /media

It works; see the line in red above. This tells us that the file system /nfs is mounted on /media from host ‘localhost’, which is just the same server.

I hope you enjoy this post.

I will at some point write about more complex scenarios, but I would like to give you the initial knowledge, so you can get up and running quickly.

 

By Renato de Oliveira

Exchange 2010 (mailbox move) and Blackberry Enterprise

Exchange 2010 (mailbox move) and Blackberry Enterprise

We have a group of users which use Blackberry phones at work, to manage these devices we have a Blackberry Enterprise Server or simple BES.

The other day we were moving some users to a new database, and for my surprise some of the Blackberries just stopped communicating with the BES server.

I started to look into this problem it was around 5:30pm, looked at all the logs, eventviewer, firewalls etc.
I looked at space on the BES server, I applied all patches, applied SP2 for Exchange 2010 and no results.

I started to look into the BES service account "BESAdmin" and its permissions. I looked at the registry keys and this is what I found.

If you moved some users to a different Exchange 2010 Database, you need to give the "BESAdmin" permissions to the new Database, see below:

Get-MailboxDatabase | Add-ADPermission -User "BESAdmin" -AccessRights ExtendedRight -ExtendedRights Receive-As, ms-Exch-Store-Admin, ms-Exch-Store-Visible

As a work around you can also do the following:

Create the following  DWORD Reg key:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\ParametersSystem\

- Maximum Allowed Sessions Per User

Note: Just set it to as many connections you need

 

Once you have added the reg key "Maximum Allowed Sessions Per User", you need to restart the service "MSExchange Information Store"

Note: Sometimes this service does not restart properly and you may need to reboot the Exchange 2010 Server.
I would strongly suggest doing this out of hours and make sure you have a back up of your registry.

by Renato de Oliveira

How to upgrade Exchange 2010 Standard to Enterprise

How to upgrade Exchange 2010 Standard to Enterprise

Recently I was looking at our Exchange 2010 and it was just growing wildly.

I had to introduce some measures to prevent things from escalating to a red alert.
I checked all mailboxes and which users were the culprit, but it is just the way most businesses use their mail system now a day. It is used for pretty much everything.

I thought about defragging the databases (we had 5 databases) and this is the limit for Standard Edition. I though, these databases must be fragmented.

I had a look at each database size and they were each larger than 100GB. To defrag a database that size it would take around 8 hours. I can’t have the server down for 8 hours.

I could create a new database, but I have used all 5 database limit for the Standard version.

I could move all users to a single database, but again this takes a long time, as each mailbox is over 8GB.

I had a look at the price to upgrade to Enterprise edition (it supports over 5 Databases), the cost was not prohibitive, and so I bought it.

Now I can create one database per department, I can move each user to their respective departmental database, empty the old databases and just delete them.

Once you create a new database and move few mailboxes, the new database will be smaller and faster, so no need to defrag and you can simply delete the old database.

Note: Be careful when moving mailboxes, Exchange 2010 generates a lot of logs, for each mailbox moved.  I would suggest keep an eye on your disk, the one which hosts the logs.

It is very easy to change from Exchange Standard to Enterprise. Just run the command below:

Command

Set-ExchangeServer -Identity “your server name” -ProductKey “your Enterprise key”

You will need to restart the information store service.

Note: I would recommend doing this out of hours, so the business does not suffer from a negative impact and downtime.

by Renato de Oliveira