Let's start with the opening act!
Users
Standard User
Super User / Administrator
Root
Why?
- Better control
- Restricted Permissions
- Multiple users can work in synchrony
Restricted Permission?
How?
Groups
Group ID: A
Users: a, b, c
Group ID: B
Users: b, c
Group ID: C
Users: c
Permissions
Read
Write
Execute
4
2
1
Demo Time!
- `ls -l`
- whoami
- groups
- id
- su
- sudo
- sudo id
- chmod
User management
create/remove users
User details stored
| Action | Command |
|---|---|
| Create user | `useradd <user>` |
| Change Password | `passwd <user>` |
| Modify user | `usermod -L <user>` `usermod -U <user>` |
| Delete user | |
| Adding new group | `groupadd -g 4001 <group> ` |
| Add user to new group | `usermod -aG <group> <user>` |
Cheat Sheet !
Softwares and packages
Why do we need software?
How to install software?
Package managers
The software to install software
But why?
Dependencies
Package manager
Demo Time!
- sudo dnf install vim
- man dnf
- dnf search <package-name>
- dnf list updates
- dnf updateinfo list --security
- dnf update
Bash
The bourne Shell
How to access shell?
Terminal Emulators
Shell Scripts
Shell scripts?
A script/file with shell (bash) instructions
But why?
Demo time!
SSH
Secure Shell Protocol
Port: 22
What is SSH?
-
Network Protocol used for remote administration
-
Created in 1995 by Tatu Ylönen, SSH protocol
-
Uses Public-key based authentication for controlled access
Why SSH?
And
Alternatives?
rlogin
telnet
ftp
How it works?
How to connect?
- SSH client
- Access permission (User and password)
- Server address (IP/URL)
ssh <user>@<ip-address>
-v: verbose
-i: identify file (.pem file)
Processes & Services
- Each program in execution is a process
- All processes are tracked by Operating system
- Linux keep process details in /etc/proc
Lifecycle of process
Process management?
View all active processes
ps
-a: all process
-u: for users in userlist
Services
Set of processes
How to manage services?
systemd
Systemd: service manager
- Check status
- Start service
- Stop service
- Control service
systemd
status
<service>
start
stop
enable
Logging
Questions?
Thank you!
Kernel (Drivers)
