My Technical Knowledge Base

Backup/transfer MySQL database with structure and datas

2006-08-01T19:12:00.000+02:00

Wondering about how to backup or transfer a mysql database from one box to another.
By transfer/backup I mean structure + datas.

There's a mysql tool called mysqldump
It's free and included by default (I suppose) in most mysql installations.

The syntax is :

mysqldump -u user -p mydatabase > file.sql

Example :

mysqldump -u cadey -p customers > customers.sql

This will generate a file called customers.sql which I can then FTP to another box.
There I'll use :

mysql customers < customers.sql

This will integrate the customers.sql datas into the customers database.

Creloaded is full of bugs

2006-07-24T13:33:00.000+02:00

As you maybe read in previous posts, I've bought the e-Commerce shopping cart called Creloaded.

I'm really disapointed with that one. It's totally full of bugs, lots of unexpected problems appear during configuration.
Their technical support give almost no answer... I get robbed, that's too bad.

I advice no one to go for their paid version.

First step in securing a linux server

2006-07-21T10:40:00.000+02:00

What to do if you want to secure a minimum your Linux box? You have to restrict SSH access to it.

Go in the /etc/ssh/sshd_config file.
There you'll see a PermitRootLogin instruction. Set it to "no". Like this, root user won't be allowed to connect using SSH.

Why the hell would you do that and then after how will you manage your server? You'll access to root commands by allowing normal users to connect to ssh, then they will issue a "su" command to become root.
This is more secure because you get bigger control. Indeed "su" commands are logged. So you will know who switched to root and when. If for instance you have 3 admins in your company and you provide "root" profile to all of them, you'll never know who did what. But if they connect with their normal user then issue a "su" command, you'll know they did it and when, they cannot negate.
Also blocking root access to SSH will block common hacking trials on your server.

Second thing I did on my box is blocking all users (but me) to access by SSH. I mean normal users (FTP accounts, email accounts...) don't need to have SSH.

To do that, go in the /etc/ssh/sshd_config file.
You can see an instruction (if not create it) AllowUsers. If you put "AllowUsers david" then only user david will be allowed to connect by ssh.
You could also use DenyUsers if you prefer, but I prefer AllowUsers

Same works for AllowHosts/DenyHosts if you only want certain hosts to be allowed to connect.

AllowOverride parameter for Apache when installating Creload

2006-07-21T10:34:00.000+02:00

Yesterday I wanted to install an e-Commerce script called Creloaded.
After installation, displaying the pages, they where showing "500 Internal Server Error".
This is an Apache error message.

How did I fix that?

First I went to look into the /var/log/apache/error.log file
It was saying "php_value not allowed".

The mistake was that in the creload directories, there are .htaccess files. Those files contains some extra configuration that have to override the default one from Apache. So it's like if you configure your Apache to tell him to speak french, and in the .htaccess file, there is an instruction that say "for that directory your going to speak english"

Doing that was not a mistake. It's just that my Apache was configured in a way to say "don't allow .htaccess files to override configuration".
The only thing I had to do was to goin in the Apache conf file (/etc/apache/httpd.conf) and add a line like this :

"AllowOverride All"

Then it worked ;-)

How to create an FTP account on a Linux server ?

2006-07-20T13:45:00.000+02:00

This morning I had to create an FTP account on a Linux Server.

I wanted to restrict access to a specific directory like /home/web1
I also wanted that the user will be called user1

It's simple, no hassle, here are the commands :

cd /home
mkdir web1
adduser user1 (then asked for password I enter it)
usermod -d /home/web1 user1

Why did I use the usermod command?

When you create an account with adduser, a default home directory will be created for the user, this directory will be mapped by default when I ftp on the linux box.
By using usermod command with -d parameter, you change the default home directory for that user.

Result : when user1 connects by ftp to the linux box, he'll be directly connected to the /home/web1 directory

To allow him to create files, I'll probably also have to do some chmod on the /home/web1 directory.