How to protect /etc/resolv.conf after reboot? (use the chattr command)

 How to protect /etc/resolv.conf after reboot? 

problems with table create user in icingaweb

problems with table create user in icingaweb: 

db troubleshooting of icinga webpage

 db troubleshooting of icinga webpage: 

How to add "live Suse" to virtualbox

 like this: 

Missing value auth-url required for auth plugin password (openstack)

 

openstack issues

how to check open ports via nc?

 how to check open ports via nc?

$ nc -zv 10.0.32.15 22

-z - only checking, no sending data

-v - verbose

How to check "lastb" in logs? (redhat)

When someone has bad password or not ssh keys. 

User root not allowed because shell bash does not exist

 

or permission denied via ssh keys? 

How to allow 22 port via ufw?

 How to allow 22 port via ufw?

How to get serial number?

How to get serial number?

Cgroups - kernel control group: ssh task

 How to use set-property or cgroups. 

output from ping -I

ping -c 3 -I (name network card) google.com

 

 

ping -I

 
ping -I

wicked configuration on Suse 15

wicked configuration:

How configure network in suse linux?

dstat on suse

 If we need next monitoring, try dstat. 

net-tools-deprecated on Suse 15

 how to install route, ifconfig on suse 15? 

 

zypper --non-interactive

 zypper --non-interactive ---> what is it?

Polkit issue with httpd:

 Polkit issue with httpd: 

How to sum files and directories in linux?

How to sum files and directories in linux? (try find and wc)

ssh -issue: no hostkeys available --exiting

 I installed Ubuntu 22.04 server for testing in my "ansible learning". First problem was with ssh. Ssh is very necessary in ansible communication. How it fixed? 

"problem with proxy to repository server" (problem with bad installation auditd)

 proxy problem

_netdev

(I tried this case study on Almalinux 9 and Almalinux8)

CASE STUDY: ROUTING ISSUE

 

CASE STUDY:  ROUTING ISSUE 

How to install wordpress via docker?

 How to install wordpress via docker?

my first docker file

My first docker file

virtulabox on Debian 12

virtulabox on Debian 12

 

kernel parameters

 Why use /etc/sysctl.conf?

we use for some kernel parameters:  (for example net.ipv4.ip.forward)


- in /proc/sys/net/ivp4/ip_forward is "live kernel data"

It's not necessary explain each command  (sysctl -p = p = load parameters from file)

[root@Mr ~]# cat /proc/sys/net/ipv4/ip_forward
0
[root@Mr ~]# vi /etc/sysctl.conf

[root@Mr ~]# cat /etc/sysctl.conf | grep -i ipv4
net.ipv4.ip_forward=1
[root@Mr ~]#



[root@Mr ~]# sysctl -p
net.ipv4.ip_forward = 1
[root@Mr ~]# cat /proc/sys/net/ipv4/ip_forward
1
[root@Mr ~]#

more: https://www.kernel.org/doc/html/v4.14/admin-guide/kernel-parameters.html

chmod ug+s

 How to use write set uid or set gid? 

Selinux and fcontext

 fcontext command: 

when you use selinux policy, you work with tool fcontext

how to check:

(for example: you have to change the apache directory:)

Problem with virt-manager (install)

I tried install virt-manager on Redhat. But I had a problem. 

pvcreate not found

 when you have a problem with command pvcreate: 

 

How to install VNC on Debian 12?

 It's easy! only click, click and dpkg ;-) 

Zoom on Debian 12

 How to install zoom on Debian 12? 

Mac address problem with ssh connetion (Ubuntu 20.04)

 Problem ssh hello@server -- not running

How to install KVM on Debian 12

How to install KVM on Debian 12? 

How to install ansible semaphore on Debian?

How to install ansible semaphore on Debian?

ansible-vault

 How to create ansible-vault to playbook? 

Ansible semaphore installation

Ansible semaphore installation 

Enable history with timestamp for new users

How to enable history with timestamp for new users?

how to install icinga2 on centos7

how to install icinga2 on centos7

How to install ntop on CentOS7

Installation ntop on CentOS7

How to change default editor?

 How to change default editor? 

ssh client and ciphers

 problem with ciphers on ssh client

puppet lock

 puppet lock

Problem with mount (syntax in /etc/fstab)

Problem with mount (syntax in /etc/fstab)

anisble playbook - update only redhat

How can we solve conditions in ansible? 

sudo -k

 How to kill sudo timeout? 

Gitlab for students: part 1: user-expire-password.sh

I'm just a normal lad from Kosice. I like Linux, devops and python and lot of thinks from open source world. 

nmcli and dns

Redhat use nmcli or nmtui tools for configuration of network. Let me explain how connect dns via nmcli too. 

gpt or mbr

How to check gpt or mbr?

grep -im1

 Grep is very important command. Let's try with m!