Articles for Linux
ZeroTier is a powerful and easy-to-use VPN solution that allows you to create secure networks and connect devices across the globe. In this guide, we will walk you through the installation process of the ZeroTier VPN client on CentOS 7.
First, you need to install the EPEL (Extra Packages for Enterprise Linux) repository, which contains additional packages for CentOS.
yum install epel-release
How to schedule a command on linux
You can edit the crontab file to execute the command on scheduled time.
Below are the examples of crontab .
Linux Crontab Format
MIN HOUR DOM MON DOW CMD
Table: Crontab Fields and Allowed Ranges (Linux Crontab Syntax)
Field Description Allowed Value
MIN Minute field 0 to 59
HOUR Hour field 0 to 23
DOM Day of Month 1-31
MON Month field 1-12
DOW Day Of Week 0-6
CMD Command Any command to be executed.
How to show line number in nano command
if you want to show line number in nano command
run nano as you run normaly when window is open just press Alt+Shift+3 it will show line number.
How to access Centos 7 with windows RDP
If you want to access your Centos 7 server with windows RDP same as you are accessing windows machine .
Then you need the following packege to install xRDP
1- Add epel reposetry
# yum install -y epel-release
2- Install xRDP
# yum install -y xrdp
Peer cert cannot be verified or peer cert invalid while using yum
If you are getting above error then perform the following to resolve the yum error.
1- check and correct the date and time of the server.
2- Check /etc/hosts file for any false DNS resolutions of servers.
3-Disable SSL verification by adding sslverify=false in /etc/yum.conf
4- Check repo file is using http or https and verify url.
How to access data after booting with Sysrcd rescue system
If you have servers in cloud or rented server on data center . some time its currepted or you need to get databack or edit and currect files.
you are booting with Sysrcd rescue system
After booting get ssh access and login
create a folder to mount your data or partition
mkdir /backup
Continue reading How to access data after booting with Sysrcd rescue system
How to public any service without public ip using OPENVPN.
Some time we want to publish our website or any service from our desktop to internet . Then we require public IP to publish our services on the internet.
So resolve this issue we can user third party services like PORTMAP.IO this gives you ability to publish your services over the internet using OPEN VPN Client.
For more information visit there website https://portmap.io/
How to configure SSL VPN on OPENVPN
If you want to configure openvpn on SSL port below are the example for server and client side.
Server side configuration
local 192.168.1.250 port 443 proto tcp dev tun ca ca.crt cert server.crt key server.key dh dh.pem auth SHA512 tls-crypt tc.key topology subnet server 10.8.0.0 255.255.255.0 #server-ipv6 fddd:1194:1194:1194::/64 #push "redirect-gateway def1 ipv6 bypass-dhcp" ## To avoid all internet traffic except VPN## push "route 192.168.29.0 255.255.255.0" ## To advertise Network ## ifconfig-pool-persist ipp.txt push "dhcp-option DNS 192.168.29.254" #push "dhcp-option DNS 8.8.4.4" keepalive 10 120 cipher AES-256-CBC user nobody duplicate-cn ##To use single certificate for multiple user# group nobody persist-key persist-tun verb 3 crl-verify crl.pem
How to setup your IT Infrastructure for Work From Home in low cost with open source secure industry standard technologies.
Here I am going to talk about talk about small and medium size offices and companies who are not able to invest big amount to upgrade or migrate there IT infrastructure for there workers to work from home in the COVID pandemic .
There are few things mostly you are using in the office as IT infrastructure as end user. if that IT infrastructure is available at your home then mostly people can work from home easily.
I am taking a small office example scenario with 30 employees which you require to work from home.
Simple small office network diagram .
Continue reading How to setup your IT Infrastructure for Work From Home
centos 5.11 yum repository
It is now EOD no updates available. but we require yum repo to install old applications .
go to and run
cd /etc/yum.repos.d for i in $(ls *.repo); do mv $i $i.orig; done
copy the below code and save as CentOS-Base.repo
# CentOS-Base.repo # # The mirror system uses the connecting IP address of the client and the # update status of each mirror to pick mirrors that are updated to and # geographically close to the client. You should use this for CentOS updates # unless you are manually picking other mirrors. # # If the mirrorlist= does not work for you, as a fall back you can try the # remarked out baseurl= line instead. # # [base] name=CentOS-$releasever - Base #mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os baseurl=http://vault.centos.org/5.11/os/$basearch gpgcheck=1 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-5 #released updates [updates] name=CentOS-$releasever - Updates #mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates baseurl=http://vault.centos.org/5.11/updates/$basearch gpgcheck=1 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-5 #packages used/produced in the build but not released [addons] name=CentOS-$releasever - Addons #mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=addons baseurl=http://vault.centos.org/5.11/addons/$basearch gpgcheck=1 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-5 #additional packages that may be useful [extras] name=CentOS-$releasever - Extras #mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras baseurl=http://vault.centos.org/5.11/extras/$basearch gpgcheck=1 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-5 #additional packages that extend functionality of existing packages [centosplus] name=CentOS-$releasever - Plus #mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=centosplus baseurl=http://vault.centos.org/5.11/centosplus/$basearch gpgcheck=1 enabled=0 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-5 #contrib - packages by Centos Users [contrib] name=CentOS-$releasever - Contrib #mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=contrib baseurl=http://vault.centos.org/5.11/contrib/$basearch gpgcheck=1 enabled=0 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-5