Upgrade from Ubuntu 16 or 17 to 18
https://www.linuxbabe.com/ubuntu/upgrade-ubuntu-16-10-17-04-to-ubuntu-18-04
First, we need to run the following command to change all instances of yakkety to bionic in the source list file (/etc/apt/sources.list). The former is the code name for Ubuntu 16.10, whereas bionic is the code name for Ubuntu 18.04.
sudo sed -i ‘s/yakkety/bionic/g’ /etc/apt/sources.list
If you are using Ubuntu 17.04, then run this command instead:
sudo sed -i ‘s/zesty/bionic/g’ /etc/apt/sources.list
Then we need to disable third-party repositories (PPAs) with the command below:
sudo sed -i ‘s/^/#/’ /etc/apt/sources.list.d/*.list
After that, update software sources and upgrade software to the latest version available in the Ubuntu 18.04 repository. This step is called minimal upgrade:
sudo apt update
sudo apt upgrade
Once minimal upgrade is finished, run the following command to begin full upgrade:
sudo apt dist-upgrade
Install Ubuntu Server Desktop UI
https://itstillworks.com/install-desktop-ubuntu-server-6780086.html
Install xrdp
https://linuxize.com/post/how-to-install-xrdp-on-ubuntu-18-04/
Install the xfce4 desktop session:
$echo xfce4-session > ~/.xsession
Error:
Authentication is required to create a color profile
Solution:
Add Filename: /etc/polkit-1/localauthority.conf.d/02-allow-colord.conf
Contents:
polkit.addRule(function(action, subject) {
if ((action.id == “org.freedesktop.color-manager.create-device” ||
action.id == “org.freedesktop.color-manager.create-profile” ||
action.id == “org.freedesktop.color-manager.delete-device” ||
action.id == “org.freedesktop.color-manager.delete-profile” ||
action.id == “org.freedesktop.color-manager.modify-device” ||
action.id == “org.freedesktop.color-manager.modify-profile”
) && (
subject.isInGroup(“{nogroup}”)
)
)
{
return polkit.Result.YES;
}
});
umount home/rma/thinclient before delete his home directory
$sudo umount $HOME/thinclient_drives
Uninstall Ubuntu Desktop
#apt-get remove ubuntu-desktop (or purge)
#autoremove
#apt-get remove gnome-shell (or purge)
#autoremove
0. enter the super user shell
sudo -i
Check open ports
nmap external IP address
1. Firewall ufw (refer to the pdf for more details)
2. ufw enable
3. ufw allow 25/tcp
root@ubuntu:~# ufw status numbered
Status: active
To Action From
— —— —-
[ 1] 80 ALLOW IN Anywhere
[ 2] 80/tcp DENY IN 162.159.209.77
[ 3] 80/tcp DENY IN 162.159.208.77
[ 4] 80/tcp DENY IN 191.96.249.53
[ 5] 80/tcp DENY IN 191.96.249.54
3. deluser, delgroup (userdel, groupdel, low-level utilities)
4. Find users and groups
cat /etc/passwd
cat /etc/group
5. usermod (Modify user account)
usermod -g (change primary group)
usermod -G (change secondary group)
usermod ©\d /srv/files/ftp ftp (change home directory)
6 Check status of services
service –status-all
7. nano search: contro+w, find next: alt+w
8. check which group a user belongs to
groups mji
9. ‘top’ show information like tasks, memory, cpu and swap. Press ‘q‘ to quit window.
10. check performance – others
iotop (showing I/O on the system)
netstat -t (showing connections)
Take a look at the apache logfiles and find out what the server did last
set some RLimits for the apache process. When these limits are reached the process will be killed, giving you some more information
11. List installed packages
apt list –installed
12. dig google.com – find out the A record of a domain
13. Search for a string in all the files in a directory
example: grep -r “mydomain.com” /etc/apache2/
14. Check open ports
netstat -anltp | grep “LISTEN”
15. Search for exact word
grep minda -r, grep -w “minda” -r
16. Using tar to compress a directory or file
$tar -czvf archive.tar.gz stuff (stuff is a folder in the current directory)
-c: Create an archive.
-z: Compress the archive with gzip.
-v: Display progress in the terminal while creating the archive, also known as “verbose” mode. The v is always optional in these commands, but it’s helpful.
-f: Allows you to specify the filename of the archive.
-p: preserve the permissions
extract
$tar -xzvf archive.tar.gz (same, but use ‘x’ instead of ‘c’)
16. curl vs Wget
curl is a tool to transfer data from or to a server, using one of the supported protocols (DICT, FILE, FTP, FTPS, GOPHER, HTTP, HTTPS, IMAP, IMAPS, LDAP, LDAPS, POP3, POP3S, RTMP, RTSP, SCP, SFTP, SMB, SMBS, SMTP, SMTPS, TELNET and TFTP). The command is designed to work without user interaction.
wget command is used to download files from networks such as the internet.
Ubuntu Repositories
https://itsfoss.com/ubuntu-repositories/
Install Proxy Server (squid)
https://phoenixnap.com/kb/setup-install-squid-proxy-server-ubuntu
