So for a long time I have alway wonder what Linux Server distribution i should chose to us. I started with Centos 6 back in 2011 as this was the linux server i was looking after at work. I then found about Ubuntu, as this my Ubuntu Desktop distribution for my daily linux driver, Ubuntu seems a good choice. I currently have one Centos 6 box running my mail server and a Ubuntu server running on a VPS for my various website.
So i want to see what the main different where between Centos and Ubuntu are and which server i should focus on. I want this guide as refence so that if i had to configure a server i had something to refer to.
I setup a KVM box and install the following VM with the following Server distribution:Centos 6,7 and Ubuntu 16.04 LTS and 18.04 LTS. Each 1 vCPU 1GB Ram,10GB HD.
What is involved of setting a the distribution up:
- Media check.
- Language Selection.
- Keyboard setup.
- Finds the disk and will format/partition for you.
- Set hostname and Configure network*.
- Select time zone.
- Set root password.
- Chose Install Type - Default is replace existing file system
- The Installs finish off by installing Packages.
Time to Install:17 mins
*Remember carefully not to miss the "configure network" box in the bottom right hand corner and remember to select "connect to network automatically". If not when you boot you will not get any network access. Although you can get around this by editing /etc/sysconfig/network-scripts/ifcfg-eth{0,1} and set ONBOOT=true
- Menu to check if you want to install centos 7
- Language Selection.
- Installation Summary, Chose which Hard disk to use and configure network settings.
- The install then begins and you then get presented to set the root password and create a user account is required, while the install is happening
- Set hostname and Configure network*.
- Select time zone.
- Set root password.
- Chose Install Type - Default is replace existing file system
- The Installs finish off by installing Packages.
Time to Install:62 mins.
This is install on about 20 Mins, but then takes ages to Post-Install task (42 Mins). This is a known bug installing centos 7 on KVM VM.
https://bugs.centos.org/view.php?id=14980#bugnotes
- Language Selection.
- Menu to chose to install Ubuntu 16.04
- Select Keyboard layout.
- Configure hostname.
- Create User and Password.
- Decide if you would like to encrypt the home partition.
- Set Time Zone
- Enter Prxoy server address if requird.
- Select if you like to install updates automatically.
- Select what packages to install. I chose SSH Server.
Time to Install:28 mins.
- Language Selection.
- Menu to chose to install Ubuntu 16.04
- Select Keyboard layout.
- Configure IP settings.
- Enter Proxy server address if required.
- Select mirror for extra software.
- Partition the disk (Default option: Guided use entire disk and don't use LVM)
- Create User and Password.
- Decide if you would like to encrypt the home partition.
- Create User and Password.
- Select what packages to install. I chose SSH Server.
Time to Install:24 mins.
In the installs above I configure the server to get their IP address using DHCP, I now want to know how easier it is to configure a static IP address on the server.
To see current NIC and IP address settings:
ifconfig
IP Config file is found in:
/etc/sysconfig/network-scripts/ifcfg-eth0
Add the following details to configure static IP address:
IPADDR=192.168.127.80
SUBNET=24
GATEWAY=192.168.127.1
To restart network:
service network restart
To set the hostname edit the following files and reboot the host:
/etc/sysconfig/network
and
/etc/hosts
To edit DNS settings edit the following file:
/etc/resolv.conf
To see current NIC and IP address settings
ip address
or you can use:
nmcli
Type nmtui command in your terminal to open network manager to configure the ip settings . This can configure IP settings and Hostname.
Use the following to apply settings.
systemctl restart network
Network settings located in the same directory, but depending on your ethernet card and systemd the name of the card can change:
/etc/sysconfig/network-scripts/ifcfg-<adaptor_name>
Edit the following file:
/etc/network/interfaces
Delete the following:
iface ens32 inet dhcp
add the following:
auto ens32
iface ens32 inet static
address 192.168.127.19
netmask 255.255.255.0
gateway 192.168.127.1
dns-search domain.local
dns-nameservers 192.168.127.10
restart network
sudo ifdown ens32 && sudo ifup ens32
or
systemctl restart networking.service
Ubuntu 18.04 uses netplan to config network interfaces.
Edit the following file:
/etc/netplan/50-cloud-init.yaml
and change to the following:
network:
version: 2
ethernets:
enp0s25:
dhcp4: no
addresses: [192.168.127.200/24]
gateway4: 192.168.127.10
nameservers:
addresses: [192.168.127.10]
Run the following command to apply the config
sudo netplan --debug apply
After the base install we needed to update the system.
Update Cmd - the -y answers yes to any prompts given:
yum -y update
20 Packages to upgrade: 89MB
Time to install the upgrades: 7 mins
Update Cmd:
yum -y update
63 Packages to upgrade: 129MB
Time to install the upgrades: 12 mins
Update Cmd:
sudo apt update and sudo apt install
or alternatively you can put these together:
sudo apt update && sudo apt install
39 Packages to upgrade: 15MB
Time to install the upgrades: 7 mins
Update Cmd:
sudo apt update and sudo apt install
78 Packages to upgrade: 30MB
Time to install the upgrades: 13 mins
The next thing i do after install is configure SSH so i can remote in to the server.
The SSH server is already installed and started, but cant login in with root account and password. I know this is unsafe but is ok for this test. So i enable root login and password authentication via ssh:
Edit the following file
/etc/ssh/sshd_config
Commented out the following lines:
PermitRootLogin = yes
PasswordAuthentication yes
restart the sshd Service
service sshd restart
I enabled this as part of the setup. So do not need to configure it here.
All distribution except Ubuntu 18.04 seem to be using LVM as a logical volume management, If you decide to choose the defaults partition options in the installer.
The following commands all seem to work in all four Distributions
df -h
cat /etc/fstab
lvdisplay
pvdisplay
lvmdiskscan
fdisk -l
All the distributions are using systemd except Centos 6 which is using init.d as its control system.
All 4 distributions seems that you can use the following commands to stop and start services
service httpd start|stop|restart
On systems running systemd the service command is linked to the systemctl cmd which is used to control services in systemd.
To enable services on start up. In Centos 6 you can use:
chkconfig httpd on
For Centos 7, Ubuntu 16.04 and 18.04 Use the following systemctl cmd:
systemctl enable httpd
Below is htop output of the system loads of each system when the system is idle.
By Default this is IP tables and it is enabled by default. Use the following command to see the current firewall rules
iptables --line -vnL
The default rules allow outbound traffic to be allowed and all inbound traffic is block except port 22, which allows SSH connections in.
To stop the firewall:
service iptables stop
To disable the firewall:
chkconfig iptables off
To allow port 80:
iptables -I INPUT 5 -i eth0 -p tcp --dport 80 -m state --state NEW,ESTABLISHED -j ACCEPT
To commit changes:
service iptables save
service iptables restart
By default Centos 7 uses firewalld and it's enabled by default and allow traffic outbound and inbound port 22.
To stop the firewall:
systemctl stop firewalld
To disable the firewall:
systemctl disable firewalld
More info to follow...
Ubuntu use UFW (Uncomplicated Firewall) by default and it's disabled by default.
To view status of UFW:
sudo ufw status verbose
All systems seem to use the same following commands:
restart
shutdown now
Centos 6, you seem to have to use:
shutdown now -h
If not it puts the server into single user mode and will not power off.
The default log locations seem to be the same on all distributions, although systemd you now use journalctl, the default path is:
/var/log
dmesg works on all distribution as well, this is for displaying kernel messages.
The following commands all work on all 4 distributions.
adduser
groupadd
usermod
chown
mkdir
| Distribution | Kernel Version |
|---|---|
| Centos 6 | 2.6.32-754.12.1.el6.x86_64 |
| Centos 7 | 3.10.0-957.10.1.el7.x86_64 |
| Ubuntu 16.04 LTS | 4.4.0-145-generic |
| Ubuntu 18.04 LTS | 4.15.0-47-generic |
I installed the following services and want to see where the config files are located and the verison of the software installed.
The packages is called httpd on Centos and apache2 on Ubuntu.
Config file: /etc/httpd/conf/httpd.conf (CentOS / Redhat)
Config file: /etc/apache2/apache2.conf (Ubuntu)
Default Website Files: /var/www/html (All Distributions)
| Distribution | Apache Version |
|---|---|
| Centos 6 | 2.4.18 |
| Centos 7 | 2.4.29 |
| Ubuntu 16.04 LTS | 4.4.0-145-generic |
| Ubuntu 18.04 LTS | 4.15.0-47-generic |
To host multiple domains or sites off of a single IP address, Apache uses "virtual host" which are normally configured in the congfile file.
Config file: /etc/nginx/nginx.conf (All Distributions)
Config file: /etc/nginx/conf.d/default.conf (centos 6 also use this config files)
Default Website Files:/usr/share/nginx/html (All Distributions)
| Distribution | Nginx Version |
|---|---|
| Centos 6 | 1.10.2 |
| Centos 7 | 1.12.2 |
| Ubuntu 16.04 LTS | 1.10.3 |
| Ubuntu 18.04 LTS | 1.14.0 |
To host multiple domains or sites off of a single IP address, Nginx Apache use serverblocks with each site has its own config file like below:
/etc/nginx/sites-available/example.com
and then create a symbolic links from these files to the sites-enabled directory:
sudo ln -s /etc/nginx/sites-available/example.com /etc/nginx/sites-enabled/
Then restrart nginx.
All Distributions are using mysql except centos 7 which is using MariaDB
| Distribution | Version | Variant |
|---|---|---|
| Centos 6 | 5.1.73-8.el6_8 | mysql |
| Centos 7 | 1:5.5.60-1.el7_5 | MariaDB |
| Ubuntu 16.04 LTS | 5.7.25 | mysql |
| Ubuntu 18.04 LTS | 5.7.25 | mysql |
Config file: /etc/samba/smb.conf (All Distributions)
| Distribution | Samba Version |
|---|---|
| Centos 6 | 3.6.23-51.el6 |
| Centos 7 | 4.8.3-4.el7 |
| Ubuntu 16.04 LTS | 4.3.11 |
| Ubuntu 18.04 LTS | 4.7.6 |
So after all this discovery work the differences between centos and ubuntu are quite small. Each distribution has its own little way of doing things. Like how to set IP network settings and how to update the system. But all the other main linux commands you will use on the system like moving files about, list dirs, greping all use the same commands.
So I am a lot happier now that i have done this little project and have learnt that it does not really matter what linux distribution you choose to focus on, you should still be able to find your self around different linux distributions.
The main thing I also noticed and have read online is that Centos/Redhat is designed for a corporate environment where Ubuntu is designed for fast moving, up and coming cloud internet companies. With Centos you are given 10 years of security updates. Where Ubuntu release a LTS every two years and this is supported for 5 years. But you can pay for a extra 5 years of security updates.
I notice that Centos did not have things like wget installed out of the box and that it had the minimal version of vim installed so things like colour syntax doesn't work when editing config files.
The other thing with CentOS is it has SELinux enabled by default. Which gives you an extra layer of security. But most people disable it if they cant get their application working.
In ubuntu the root account is disabled and you have to setup user accounts and then use sudo to run commands as root. This is configured out of the box, where compared to Centos out of the box you have to use the root account and you have to add users and setup sudo.
So to me I like Ubuntu server more then Centos and think this is what I am going to focus on. I am really impressed with 18.04 edition and like the install. But i will be keeping an eye on Centos as I still need to look after a couple of these boxes.