NTP Server CentOS 7

NTPD - Configure NTP Server

Install NTPd and Configure NTP server for time adjustment. NTP uses 123/UDP

[root@dlp ~]#

yum -y install ntp

[root@dlp ~]#

vi /etc/ntp.conf

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Initial Setting CentOS 7 - Configure VIM

Install and Configure vim that is more convenience than vi.

Install vim
[root@dlp ~]# yum -y install vim-enhanced 

Set command alias. ( Apply to all users below. If you apply to a user, Write the same settings in '~/.bashrc' )

[root@dlp ~]#

vi /etc/profile

# add at the last line

alias vi='vim'

[root@dlp ~]# source /etc/profile

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Initial Setting CentOS 7 - Add Repository

Add some useful external repositories to install useful softwares
Install a plugin to add priorities to each installed repositories.

[root@dlp ~]#

yum -y install yum-plugin-priorities

# set [priority=1] to official repository

[root@dlp ~]# sed -i -e "s/\]$/\]\npriority=1/g" /etc/yum.repos.d/CentOS-Base.repo

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Initial Setting CentOS 7 - Update System

After installing CentOS, Update the system first if possible.

[root@dlp ~]# yum -y update 

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Initial Setting CentOS 7 - Services

It's possible to make sure services' status like follows

# display the list of services which are running

[root@dlp ~]# 

systemctl -t service 

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Initial Seting CentOS 7 - Network Setting

Set static IP address to the server
Replace the interface name "eno16777736" for your own environment's one

# set hostname

[root@localhost ~]#

hostnamectl set-hostname dlp.server.world

# display devices

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Initial Setting CentOS 7 - Firewall and Selinux

FIREWALL

If the Firewall on the server is unnecessarry (for example, because some firewalls are allready running in your LAN ),
then stop it like follows.

If needs, refer to here to configure Firewalld.

[root@dlp ~]# 

systemctl stop firewalld 

[root@dlp ~]# 

systemctl disable firewalld 

rm '/etc/systemd/system/dbus-org.fedoraproject.FirewallD1.service'
rm '/etc/systemd/system/basic.target.wants/firewalld.service'

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Basic Operation of Firewalld Centos 7

This is the Basic Operation of Firewalld.

The definition of services is set to zones on Firewalld. To enable Firewall, assosiate a zone to a NIC with related commands.

1. To use Firewalld, start it

[root@dlp ~]# 

systemctl start firewalld 

[root@dlp ~]# 

systemctl enable firewalld 

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Initial Setting CentOS 7 - Add an User

Add an User "cent" as an example below.

[root@dlp ~]# 

useradd cent 

[root@dlp ~]# 

passwd cent 

Changing password for user cent.
New UNIX password:

# set password

Retype new UNIX password:

# confirm

passwd: all authentication tokens updated successfully.
[root@dlp ~]# 

exit 

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Install Centos 7

Insert CentOS install disk and start the Computer. Then, Following screen is displayed, Push Enter key to proceed.

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Debian/Ubuntu Linux: Restrict an SSH user session to a specific directory by setting chrooted jail

I setup a web-server. I need to grant a user ssh access but I do not trust users. How can I limit user session to a specific directory such as /home/httpd/$USERNAME? How do I set up a ssh chroort jail on a Linux operating systems?

You can interactive shell with special root directory on a Linux or Unix-like systems. You can set the pathname (such as /home/httpd/foo) of a directory to chroot to after authentication. All components of the pathname must be root owned directories that are not writable by any other user or group. After the chroot, sshd changes the working directory to the user's home directory.

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