CentOS 5.1 Server Setup Notes

CentOS 5.1 Server Setup: LAMP, Email, DNS, FTP, ISPConfig (a.k.a. The Perfect Server)

This tutorial shows how to set up a CentOS 5.1 based server that offers all services needed by ISPs and web hosters: Apache web server (SSL-capable), Postfix mail server with SMTP-AUTH and TLS, BIND DNS server, Proftpd FTP server, MySQL server, Dovecot POP3/IMAP, Quota, Firewall, etc. This tutorial is written for the 32-bit version of CentOS 5.1, but should apply to the 64-bit version with very little modifications as well.
 
I will use the following software:
  • Web Server: Apache 2.2 with PHP 5.1.6
  • Database Server: MySQL 5.0
  • Mail Server: Postfix
  • DNS Server: BIND9 (chrooted)
  • FTP Server: Proftpd
  • POP3/IMAP server: Dovecot
  • Webalizer for web site statistics
In the end you should have a system that works reliably, and if you like you can install the free webhosting control panel ISPConfig (i.e., ISPConfig runs on it out of the box).
I want to say first that this is not the only way of setting up such a system. There are many ways of achieving this goal but this is the way I take. I do not issue any guarantee that this will work for you!

1 Requirements

To install such a system you will need the following:
  • Download the CentOS 5.1 DVD or the six CentOS 5.1 CDs from a mirror next to you (the list of mirrors can be found here: http://isoredirect.centos.org/centos/5/isos/i386/).
  • a fast internet connection.

2 Preliminary Note

In this tutorial I use the hostname server1.example.com with the IP address 192.168.0.100 and the gateway 192.168.0.1. These settings might differ for you, so you have to replace them where appropriate.

3 Install The Base System

Boot from your first CentOS 5.1 CD (CD 1) or the CentOS 5.1 DVD. Press <ENTER> at the boot prompt:
 
It can take a long time to test the installation media so we skip this test here:
 
The welcome screen of the CentOS installer appears. Click on Next:
 
Choose your language next:
 
Select your keyboard layout:
 
I’m installing CentOS 5.1 on a fresh system, so I answer Yes to the question Would you like to initialize this drive, erasing ALL DATA?
 
Now we must select a partitioning scheme for our installation. For simplicity’s sake I select Remove linux partitions on selected drives and create default layout. This will result in a small /boot and a large / partition as well as a swap partition. Of course, you’re free to partition your hard drive however you like it. Then I hit Next:
 
Answer the following question (Are you sure you want to do this?) with Yes:
 
On to the network settings. The default setting here is to configure the network interfaces with DHCP, but we are installing a server, so static IP addresses are not a bad idea… Click on the Edit button at the top right.
 
In the window that pops up uncheck Use dynamic IP configuration (DHCP) and Enable IPv6 support and give your network card a static IP address (in this tutorial I’m using the IP address 192.168.0.100 for demonstration purposes) and a suitable netmask (e.g. 255.255.255.0; if you are not sure about the right values, my other posts would help you):
 
Set the hostname manually, e.g. server1.example.com, and enter a gateway (e.g. 192.168.0.1) and up to two DNS servers (e.g. 145.253.2.75 and 193.174.32.18):
 
Choose your time zone:
 
Give root a password:
 
Now we select the software we want to install. Select nothing but Server (uncheck everything else). Also don’t check Packages from CentOS Extras. Then check Customize now, and click on Next:
 
Now we must select the package groups we want to install. Select Editors, Text-based Internet, Development Libraries, Development Tools, DNS Name Server, FTP Server, Mail Server, MySQL Database, Server Configuration Tools, Web Server, Administration Tools, Base, and System Tools (unselect all other package groups) and click on Next:
 
The installer checks the dependencies of the selected packages:
 
Click on Next to start the installation:
 
The hard drive will then get formatted:
 
The installation begins. This will take a few minutes:
 
Finally, the installation is complete, and you can remove your CD or DVD from the computer and reboot it:
 
After the reboot, you will see this screen. Select Firewall configuration and hit Run Tool:
 
I want to install ISPConfig at the end of this tutorial which comes with its own firewall. That’s why I disable the default CentOS firewall now. Of course, you are free to leave it on and configure it to your needs (but then you shouldn’t use any other firewall later on as it will most probably interfere with the CentOS firewall).
 
SELinux is a security extension of CentOS that should provide extended security. In my opinion you don’t need it to configure a secure system, and it usually causes more problems than advantages (think of it after you have done a week of trouble-shooting because some service wasn’t working as expected, and then you find out that everything was ok, only SELinux was causing the problem). Therefore I disable it, too (this is a must if you want to install ISPConfig later on). Hit OK afterwards:
 
Then leave the Setup Agent by selecting Exit:
 
Then log in as root and reboot the system so that your changes can be applied:
shutdown -r now
Now, on to the configuration…
——————————————————————————————————————————————–
 

4 Adjust /etc/hosts

Next we edit /etc/hosts. Make it look like this:
vi /etc/hosts
# Do not remove the following line, or various programs
# that require network functionality will fail.
127.0.0.1 localhost.localdomain localhost
192.168.0.100 server1.example.com server1
::1 localhost6.localdomain6 localhost6
 

5 Configure Additional IP Addresses

(This section is totally optional. It just shows how to add additional IP addresses to your network interface eth0 if you need more than one IP address. If you’re fine with one IP address, you can skip this section.)
Let’s assume our network interface is eth0. Then there is a file /etc/sysconfig/network-scripts/ifcfg-eth0 which contains the settings for eth0. We can use this as a sample for our new virtual network interface eth0:0:
cp /etc/sysconfig/network-scripts/ifcfg-eth0 /etc/sysconfig/network-scripts/ifcfg-eth0:0
Now we want to use the IP address 192.168.0.101 on the virtual interface eth0:0. Therefore we open the file /etc/sysconfig/network-scripts/ifcfg-eth0:0 and modify it as follows (we can leave out the HWADDR line as it is the same physical network card):
vi /etc/sysconfig/network-scripts/ifcfg-eth0:0
# Advanced Micro Devices [AMD] 79c970 [PCnet32 LANCE]
DEVICE=eth0:0
BOOTPROTO=static
BROADCAST=192.168.0.255
IPADDR=192.168.0.101
NETMASK=255.255.255.0
NETWORK=192.168.0.0
ONBOOT=yes
Afterwards we have to restart the network:
/etc/init.d/network restart
You might also want to adjust /etc/hosts after you have added new IP addresses, although this is not necessary.
Now run
ifconfig
You should now see your new IP address in the output:
[root@server1 ~]# ifconfig
eth0      Link encap:Ethernet  HWaddr 00:0C:29:55:33:B3
          inet addr:192.168.0.100  Bcast:192.168.0.255  Mask:255.255.255.0
          inet6 addr: fe80::20c:29ff:fe55:33b3/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:355 errors:0 dropped:0 overruns:0 frame:0
          TX packets:300 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:31326 (30.5 KiB)  TX bytes:47669 (46.5 KiB)
          Interrupt:177 Base address:0x1400
 
eth0:0    Link encap:Ethernet  HWaddr 00:0C:29:55:33:B3
          inet addr:192.168.0.101  Bcast:192.168.0.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          Interrupt:177 Base address:0x1400
 
lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:8 errors:0 dropped:0 overruns:0 frame:0
          TX packets:8 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:560 (560.0 b)  TX bytes:560 (560.0 b)
 
[root@server1 ~]#

6 Disable The Firewall And SELinux

SELinux is a security extension of CentOS that should provide extended security. You can skip this chapter if you have already disabled the firewall and SELinux at the end of the basic system installation in the Setup Agent
 
I want to install ISPConfig at the end of this tutorial which comes with its own firewall. That’s why I disable the default CentOS firewall now. Of course, you are free to leave it on and configure it to your needs (but then you shouldn’t use any other firewall later on as it will most probably interfere with the CentOS firewall).
 
Run
system-config-securitylevel
Set both Security Level and SELinux to Disabled and hit OK:
 
Afterwards we must reboot the system:
shutdown -r now
 

7 Install Some Software

First we import the GPG keys for software packages:
rpm –import /etc/pki/rpm-gpg/RPM-GPG-KEY*
Then we update our existing packages on the system:
yum update
Now we install some software packages that are needed later on:
yum install fetchmail wget bzip2 unzip zip nmap openssl lynx fileutils ncftp gcc gcc-c++
 
——————————————————————————————————-

8 Quota

(If you have chosen a different partitioning scheme than I did, you must adjust this chapter so that quota applies to the partitions where you need it.)
To install quota, we run this command:
yum install quota
Edit /etc/fstab and add ,usrquota,grpquota to the / partition (/dev/VolGroup00/LogVol00):
vi /etc/fstab
/dev/VolGroup00/LogVol00 / ext3 defaults,usrquota,grpquota 1 1
LABEL=/boot /boot ext3 defaults 1 2
tmpfs /dev/shm tmpfs defaults 0 0
devpts /dev/pts devpts gid=5,mode=620 0 0
sysfs /sys sysfs defaults 0 0
proc /proc proc defaults 0 0
/dev/VolGroup00/LogVol01 swap swap defaults 0 0
Then run
touch /aquota.user /aquota.group
chmod 600 /aquota.*
mount -o remount /
quotacheck -avugm
quotaon -avug
to enable quota.
 

9 Install A Chrooted DNS Server (BIND9)

To install a chrooted BIND9, we do this:
yum install bind-chroot
Then do this:
chmod 755 /var/named/
chmod 775 /var/named/chroot/
chmod 775 /var/named/chroot/var/
chmod 775 /var/named/chroot/var/named/
chmod 775 /var/named/chroot/var/run/
chmod 777 /var/named/chroot/var/run/named/
cd /var/named/chroot/var/named/
ln -s ../../ chroot
cp /usr/share/doc/bind-9.3.3/sample/var/named/named.local /var/named/chroot/var/named/named.local
cp /usr/share/doc/bind-9.3.3/sample/var/named/named.root /var/named/chroot/var/named/named.root
touch /var/named/chroot/etc/named.conf
chkconfig –levels 235 named on
/etc/init.d/named start
BIND will run in a chroot jail under /var/named/chroot/var/named/. I will use ISPConfig to configure BIND (zones, etc.).
 

10 MySQL (5.0)

To install MySQL, we do this:
yum install mysql mysql-devel mysql-server
Then we create the system startup links for MySQL (so that MySQL starts automatically whenever the system boots) and start the MySQL server:
chkconfig –levels 235 mysqld on
/etc/init.d/mysqld start
Now check that networking is enabled. Run
netstat -tap | grep mysql
It should show a line like this:
[root@server1 named]# netstat -tap | grep mysql
tcp        0      0 *:mysql                     *:*                         LISTEN      2470/mysqld
[root@server1 named]#
If it does not, edit /etc/my.cnf and comment out the option skip-networking:
vi /etc/my.cnf
#skip-networking
and restart your MySQL server:
/etc/init.d/mysqld restart
Run
mysqladmin -u root password yourrootsqlpassword
mysqladmin -h server1.example.com -u root password yourrootsqlpassword
to set a password for the user root (otherwise anybody can access your MySQL database!).
—————————————————————————————————————————–

11 Postfix With SMTP-AUTH And TLS

Now we install Postfix and Dovecot (Dovecot will be our POP3/IMAP server):
yum install cyrus-sasl cyrus-sasl-devel cyrus-sasl-gssapi cyrus-sasl-md5 cyrus-sasl-plain postfix dovecot
Next we configure SMTP-AUTH and TLS:
postconf -e ‘smtpd_sasl_local_domain =’
postconf -e ‘smtpd_sasl_auth_enable = yes’
postconf -e ‘smtpd_sasl_security_options = noanonymous’
postconf -e ‘broken_sasl_auth_clients = yes’
postconf -e ‘smtpd_recipient_restrictions = permit_sasl_authenticated,permit_mynetworks,reject_unauth_destination’
postconf -e ‘inet_interfaces = all’
postconf -e ‘mynetworks = 127.0.0.0/8’
We must edit /usr/lib/sasl2/smtpd.conf so that Postfix allows PLAIN and LOGIN logins. On a 64Bit Centos 5.1 you must edit the file /usr/lib64/sasl2/smtpd.conf instead. It should look like this:
vi /usr/lib/sasl2/smtpd.conf
pwcheck_method: saslauthd
mech_list: plain login
Afterwards we create the certificates for TLS:
mkdir /etc/postfix/ssl
cd /etc/postfix/ssl/
openssl genrsa -des3 -rand /etc/hosts -out smtpd.key 1024
chmod 600 smtpd.key
openssl req -new -key smtpd.key -out smtpd.csr
openssl x509 -req -days 3650 -in smtpd.csr -signkey smtpd.key -out smtpd.crt
openssl rsa -in smtpd.key -out smtpd.key.unencrypted
mv -f smtpd.key.unencrypted smtpd.key
openssl req -new -x509 -extensions v3_ca -keyout cakey.pem -out cacert.pem -days 3650
Next we configure Postfix for TLS:
postconf -e ‘smtpd_tls_auth_only = no’
postconf -e ‘smtp_use_tls = yes’
postconf -e ‘smtpd_use_tls = yes’
postconf -e ‘smtp_tls_note_starttls_offer = yes’
postconf -e ‘smtpd_tls_key_file = /etc/postfix/ssl/smtpd.key’
postconf -e ‘smtpd_tls_cert_file = /etc/postfix/ssl/smtpd.crt’
postconf -e ‘smtpd_tls_CAfile = /etc/postfix/ssl/cacert.pem’
postconf -e ‘smtpd_tls_loglevel = 1’
postconf -e ‘smtpd_tls_received_header = yes’
postconf -e ‘smtpd_tls_session_cache_timeout = 3600s’
postconf -e ‘tls_random_source = dev:/dev/urandom’
Then we set the hostname in our Postfix installation (make sure you replace server1.example.com with your own hostname):
postconf -e ‘myhostname = server1.example.com’
After these configuration steps you should now have a /etc/postfix/main.cf that looks like this (I have removed all comments from it):
cat /etc/postfix/main.cf
queue_directory = /var/spool/postfix
command_directory = /usr/sbin
daemon_directory = /usr/libexec/postfix
mail_owner = postfix
inet_interfaces = all
mydestination = $myhostname, localhost.$mydomain, localhost
unknown_local_recipient_reject_code = 550
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
debug_peer_level = 2
debugger_command =
PATH=/bin:/usr/bin:/usr/local/bin:/usr/X11R6/bin
xxgdb $daemon_directory/$process_name $process_id & sleep 5
 
sendmail_path = /usr/sbin/sendmail.postfix
newaliases_path = /usr/bin/newaliases.postfix
mailq_path = /usr/bin/mailq.postfix
setgid_group = postdrop
html_directory = no
manpage_directory = /usr/share/man
sample_directory = /usr/share/doc/postfix-2.3.3/samples
readme_directory = /usr/share/doc/postfix-2.3.3/README_FILES
smtpd_sasl_local_domain =
smtpd_sasl_auth_enable = yes
smtpd_sasl_security_options = noanonymous
broken_sasl_auth_clients = yes
smtpd_recipient_restrictions = permit_sasl_authenticated,permit_mynetworks,reject_unauth_destination
mynetworks = 127.0.0.0/8
smtpd_tls_auth_only = no
smtp_use_tls = yes
smtpd_use_tls = yes
smtp_tls_note_starttls_offer = yes
smtpd_tls_key_file = /etc/postfix/ssl/smtpd.key
smtpd_tls_cert_file = /etc/postfix/ssl/smtpd.crt
smtpd_tls_CAfile = /etc/postfix/ssl/cacert.pem
smtpd_tls_loglevel = 1
smtpd_tls_received_header = yes
smtpd_tls_session_cache_timeout = 3600s
tls_random_source = dev:/dev/urandom
myhostname = server1.example.com
By default, CentOS’ Dovecot daemon provides only IMAP and IMAPs services. Because we also want POP3 and POP3s we must configure Dovecot to do so. We edit /etc/dovecot.conf and enable the line protocols = imap imaps pop3 pop3s:
vi /etc/dovecot.conf
[…]
# Base directory where to store runtime data.
#base_dir =

Don’t forget to re-enable SELinux. Please be advised that SELinux is a beast to tame. Keep reading to learn how to control such powerful pets. Ciaos.

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