Post

Linux - CentOS

Posted Updated
By Grace L
5 min read

CentOS

[toc]

check Version

$ cat /etc/os-release $ cat /etc/centos-release CentOS Linux release 8.1.1911 (Core)

Setup

kernel

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check the exact version of
    kernel uname -a.

check the kernel sources
    rpm -q kernel-devel
    yum install kernel-devel

If yum is unable to find one or more of these packages, try your luck with PBone. You should find the required packages there. When you download them, install them with either of those:
    rpm -i PACKAGE.rpm
    rpm -Uvh PACKAGE.rpm

yum install on gcc, bison, flex, qt4-devel and libstdc++.

check for the availability of some other packages:

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rpm -q bison
rpm -q bison-devel
rpm -q ncurses
rpm -q ncurses-devel
rpm -q zlib
rpm -q zlib-devel
rpm -q openssl
rpm -q openssl-devel
rpm -q gnutls-devel
rpm -q gcc
rpm -q gcc-c++

If any of those packages are not installed install them by using yum

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yum install bison
yum install bison-devel
yum install ncurses
yum install ncurses-devel
yum install zlib
yum install zlib-devel
yum install openssl
yum install openssl-devel
yum install gnutls-devel
yum install gcc
yum install gcc-c++

Enable CentOS 8 PowerTools Repo

error: no match for libpcap-devel

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the PowerTools repo may be required for some packages in the EPEL Repo.  Below are instructions on how to enable it.

# vim /etc/yum.repos.d/CentOS-PowerTools.repo
//
Change enabled=0 to enabled=1
// the PowerTools repo is now enabled

set hostname

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$ hostnamectl set-hostname server0

$ hostnamectl
   Static hostname: server0
         Icon name: computer-vm
           Chassis: vm
        Machine ID: 0531f0dd6691457fb41fa44d880f7900
           Boot ID: 970e3ca5b1294adb81683deed6b6b75d
    Virtualization: oracle
  Operating System: CentOS Linux 8 (Core)
       CPE OS Name: cpe:/o:centos:centos:8
            Kernel: Linux 4.18.0-147.8.1.el8_1.x86_64
      Architecture: x86-64

VPS

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update VPS.

    $ yum -y update

GNOME desktop environment

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!!!!!!!!!!!
To install the GNOME desktop environment
    $ sudo yum group install GNOME

To get information about the GNOME group:
    $ sudo yum group info GNOME

to check for the correct group name:
    $ sudo yum group list hidden


The list of available groups can be shown:
    $ yum grouplist


install a window manager in order to get a full-featured GUI desktop. You can use the command

$ sudo yum groupinstall "GNOME Desktop Environment"

$ sudo yum -y groupinstall "GNOME Desktop"

To install GNOME Desktop:
$ yum groupinstall "X Window System" Desktop

gcc compiler

The gcc compiler is not in your $PATH. either dont have gcc installed or its not in your $PATH variable.

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To install gcc use this: (run as root)

CentOS:
    yum install gcc
    yum groupinstall "Development Tools"
    yum groupinstall "Server with GUI"
    yum groupinstall "Graphical Administration Tools"


Debian base:

    apt-get install build-essential

firewall

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firewall-cmd --list-all

firewall-cmd --permanet --zone=public --add-service=ssh
firewall-cmd --reload

VNC

1. Installing the required packages

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The server package is called 'vnc-server'

    $ rpm -q vnc-server
    // package vnc-server is not installed
    // vnc-server-4.0-11.el4.

    If the server is not installed
    $ yum install vnc-server


The client program is 'vnc'.

    $ rpm -q vnc
    // not already installed.
    $ yum install vnc


If you are a minimalist, or simply testing, simple XTERM client:
    $ yum install xterm

2. Configuring un-encrypted VNC

We will be setting up VNC for 3 users. These will be ‘larry’, ‘moe’, and ‘curly’

Create the VNC users accounts. Edit the server configuration. Set your users’ VNC passwords. Confirm that the vncserver will start and stop cleanly. Create and customize xstartup scripts. Amend the iptables. Start the VNC service. Test each VNC user. Additional optional enhancements

2.1. Create the VNC user accounts

6. VNC-Server for an already logged in GUI console session - 2 options

https://wiki.centos.org/HowTos/VNC-Server#Start_the_VNC_server

vnc-server install will require no third party repos or source building.

x11vnc is a way to view remotely and interact with real X displays (i.e. a display corresponding to a physical monitor, keyboard, and mouse) with any VNC viewer. In this way it plays the role for Unix/X11 that WinVNC plays for Windows.

6.1. x11vnc adhoc option

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1. Download the latest rpm to the host you want the vnc-client to connect to:

wget https://dag.wieers.com/rpm/packages/x11vnc/x11vnc-0.9.3-1.el5.rf.i386.rpm


2. Install, as root, via the yum or rpm programs on the host you want the vnc-client to connect to:

yum install x11vnc-0.9.3-1.el5.rf.i386.rpm



3. Start the x11vnc process on the host you want the vnc-client to connect to.

take a long look at the possible options from the x11vnc website.
A very simple/insecure example for a trusted network setup (local network or VPN) is to have the user with the GUI console issue the command:

[user@helpme_host ~$] x11vnc -nopw -display :0.0


Then connect (without password) via a vnc-client to the IP/hostname and port noted by the x11vnc command. By default, x11vnc will allow connections from all interfaces. Host based firewall settings may need to be modified.

You can combine this with ssh tunneling:


ssh -C -t -L 5900:localhost:5900 [remote ip] 'x11vnc -usepw -localhost -display :0'
Note that the -C flag is for compression, so may not be required

Remote Installation (SSH/PuTTY)

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30System, Basic
Linux
This post is licensed under CC BY 4.0 by the author.

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