A Beginner's Guide to Setting Up A Web Hosting System (Or, the design and implementation of a system for the worldwide distribution of pictures of

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Maud Campbell
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1 A Beginner's Guide to Setting Up A Web Hosting System (Or, the design and implementation of a system for the worldwide distribution of pictures of cats.)

2 Yes, you can download the slides

3 In The Beginning

4 A brief history of a web request User types in a URL Browser breaks the request into pieces: 1. Protocol (http, ftp, gopher, etc.) 2. Domain name or IP address 3. Path If it's a name, asks the resolver (handwaving here, because what the resolver is and how it behaves varies and almost never matters) for the IP. Resolver queries root name servers for the authoritative name server. Uses new-found name server details to find out the IP address. Sends an HTTP request to server. Server returns data, and browser displays it.

Path If it's a name, asks the resolver (handwaving here, because what the resolver is and how it behaves varies and almost never

5 Well, Obviously

6 The LAMP Stack (LAMPBPDAHOOPTCTTMTWAMAP) 1. Linux 2. Apache 3. MySQL 4. PHP/Perl/Python/Ruby (that's Ruby with a P) 5. BIND 6. Postfix/Sendmail 7. Dovecot 8. And hundreds of other pieces that come together to make the world a more awesome place

7 DNS You're doing it wrong

8 How DNS Really Works (The handwaving version) 1. You "buy" a domain name 2. Registrar creates a record in the root name servers 3. Clients query root servers, and then your servers (assuming root servers have accurate information) 4. DNS servers along the way cache the information, making DNS awesomecrazyfast when you do it right

Clients query root servers, and then your servers (assuming root servers have

10 Installing a name server There are many name servers, but BIND serves more than 75% of the world's DNS traffic, so it's probably good enough for us. You don't have to run your own name server, but you need to understand how DNS works, no matter what. Red Hat, CentOS, Fedora, Scientific Linux, etc. $ sudo yum install bind dnsutils Debian, Ubuntu $ sudo apt-get update $ sudo apt-get install bind9 dnsutils

You don't have to run your own name server, but you need to understand how DNS works, no matter what.

11 Configuring BIND Add a zone (probably in /var/named/chroot/var/named or similar) $ttl IN SOA xenhost.virtualmin.com. ( ; serial ; refresh 3600 ; retry ; expire ) ; negative TTL virtualmin.com. IN NS ns1.virtualmin.com. virtualmin.com. IN NS ns2.virtualmin.com.

( 1244378204 ; serial 10800 ; refresh 3600 ; retry 604800 ; expire 38400 )

12 Configuring BIND Continued Add some records virtualmin.com. IN A IN A mail.virtualmin.com. IN A IN MX 5 mail

13 Configuring BIND Continued Check the configuration # named-checkconf -t <path to chroot> Restart BIND RHEL, CentOS, Fedora, etc. # service bind restart Debian, Ubuntu # /etc/init.d/bind9 restart

14 It isn't working! Use whois to make sure you got it right at the root servers. # whois virtualmin.com

15 HTTP (A lot simpler than DNS, and I can prove it) $ telnet virtualmin.com 80 Trying Connected to virtualmin.com ( ). Escape character is '^]'. GET / HTTP/1.1 host:

.. Connected to virtualmin.com (67.228.198.99).

16 Installing Apache Red Hat, CentOS, Fedora, etc. $ sudo yum install httpd Debian, Ubuntu $ sudo apt-get update $ sudo apt-get install apache2 apache2-mpmprefork

18 Configuring Apache Pretend like the single-site mode of Apache does not exist. Always use VirtualHosts, even if you only want one domain, because some day you'll want a second, I guarantee it.

19 Configuring Apache VirtualHosts NameVirtualHost :80... <VirtualHost :80> ServerName virtualmin.com ServerAlias DocumentRoot /home/virtualmin/public_html ScriptAlias /cgi-bin/ /home/virtualmin/cgi-bin/ DirectoryIndex index.html index.htm index.php <Directory /home/virtualmin/cgi-bin> allow from all </Directory> </VirtualHost>

com DocumentRoot /home/virtualmin/public_html ScriptAlias /cgi-bin/

20 CGI Scripts <VirtualHost :80> ServerName virtualmin.com ServerAlias DocumentRoot /home/virtualmin/public_html ScriptAlias /cgi-bin/ /home/virtualmin/cgi-bin/ DirectoryIndex index.html index.htm index.php <Directory /home/virtualmin/cgi-bin> allow from all </Directory> </VirtualHost>

21 A Simple CGI Application #! /usr/bin/perl use warnings; use strict; print "Content-type:text/html\n\n"; print "<html><head><title>hello World!</title></head>\n\n"; print "<body>\n"; print "<p>hello world!</p>\n"; print "</body></html>";

22 What about PHP? PHP can run as a CGI, so it should already work in ~/cgibin, but you pay a performance penalty. So, we can add mod_php or mod_fcgid to the picture to PHP is always running. I recommend mod_fcgid (and suexec), but I'm going to cover mod_php because it's simpler, and this is a beginner's guide. At the end, I'll tell you how to automatically get a working suexec+fcgid environment for PHP, and any other language that works with fcgid.

24 Installing mod_php Red Hat, Fedora, CentOS, etc. $ sudo yum install php Debian, Ubuntu $ sudo apt-get update $ sudo apt-get install php5 libapache2-modphp5

25 Configuring PHP It's probably already done for you. The PHP packages on both Red Hat and Debian based systems include a default configuration that'll probably Just Work(tm). But, just in case: Red Hat, CentOS, Fedora: Edit /etc/httpd/conf.d/php.conf, remove the # in front of the DirectoryIndex, AddHandler, and AddType directives. Debian, Ubuntu: $ sudo a2enmod php5

26 A Simple PHP Application This goes in ~/public_html, rather than ~/cgi-bin <?php phpinfo();?>

27 Let us now speak of databases

28 MySQL A database stores data. A relational database stores data and provides mechanisms to find specific pieces of data based on relationships to other data. MySQL also happens to be required for the vast majority of large web applications (Drupal, Joomla, Wordpress, Ruby On Rails, MediaWiki, etc.).

29 Installing MySQL Red Hat, CentOS, Fedora, etc. $ sudo yum install mysql mysql-server php-mysql Debian, Ubuntu $ sudo apt-get update $ sudo apt-get install mysql-server mysqlcommon mysql-client php5-mysql

30 Configuring MySQL Copy an appropriate /etc/my.cnf (if one does not already exist) from the install directory, and set a root password. Don't touch anything else, until you know what you're doing. # mysqladmin -u root password 'newpassword'# sudo /etc/init.d/mysqld restart

31 Now we're gonna riff on for a couple bars

32 Mail is not a single thing "My isn't working" is not a sensible thing to say, unless all mail services are not working. is made up of: 1. Message Transfer Agent/SMTP Server (Sendmail, Postfix, Exim, QMail) 2. IMAP/POP Server (Dovecot, Cyrus, Courier, etc.) 3. Delivery Agent (procmail, binmail, maildrop, postdrop, etc.) 4. Optional Spam and Anti-virus servers (SpamAssassin, ClamAV, etc.) 5. Mail Retrieval Agent (i.e. "mail client", Outlook (lookout!), Thunderbird, RoundCube, Usermin, Mail.app)

34 Installing a Mail Server (all the pieces) Make sure your system has a fully qualified domain name! (I'm serious.) Red Hat, Fedora, CentOS, etc. $ sudo yum install postfix procmail dovecot spamassassin There are no ClamAV packages in RHEL/CentOS. Debian, Ubuntu $ sudo apt-get update $ sudo apt-get install postfix postfix-pcre procmail dovecot spamassassin spamc clamavbase clamav-daemon clamav clamav-freshclam clamav-docs

35 Configuring a Mail Server You don't (much). The mail stack packages on the distributions we're talking about almost work right out of the box for simple deployments. If you find yourself following a big complicated tutorial, the tutorial is doing it wrong (or, at least, wrong for you at this time). Handwaving, because there's no way I can cover all of the details of this.

36 The Promised Land (Or, the point in our story in which I show you how to do all of this, and a whole lot more, with a single command.)

38 It was all for your own good

39 The command Go here: Read the page. Download the Virtualmin GPL install script. Run it like this: # /bin/sh install.sh

Setup a Virtual Host/Website

Setup a Virtual Host/Website Contents Goals... 2 Setup a Website in CentOS... 2 Create the Document Root... 2 Sample Index File... 2 Configuration... 3 How to Check If Your Website is Working... 5 Setup