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Reduce Ubuntu Server

· 3 min read

0. Sizes for /boot and /boot/efi​

  • /boot Partition: You could reduce the /boot partition size to around 200 MB. This should still be sufficient to hold the kernel and initramfs image. Be cautious, as going too small could lead to issues during unexpected updates or changes that might require space, such as security patches for the kernel.
  • /boot/efi Partition: The EFI System Partition (/boot/efi) typically doesn't require much space if you're only using a few boot loaders. A size of 100 MB is often recommended as a minimum by many Linux distributions and should be more than adequate for most single-boot configurations.

1. Install pre-installed ubuntu server​

2. Remove Unnecessary Packages (compile envionrment)​

After installation, you can remove packages that are not necessary for your server's purpose:

  • List installed packages:
dpkg-query -W --showformat='${Installed-Size}\t${Package}\n' | awk '{print $1/1024 " MB\t" $2}' | sort -n -r

How To Download Packages With Dependencies Locally In Ubuntu, Debian, Linux Mint, Pop OS

· One min read

How To Download Packages With Dependencies Locally In Ubuntu, Debian, Linux Mint, Pop OSLink Text​

Method 1​

sudo apt-get install --download-only <package_name>

All downloaded files will be saved in /var/cache/apt/archives directory.

sudo dpkg -i *

Method 2​

if we have installed packages already, use the apt-rdepends

$ sudo apt install apt-rdepends

apt download $(apt-rdepends vim | grep -v "^ ")

if we get errors like this

E: Can't select candidate version from package debconf-2.0 as it has no candidate

delete version specified in name like this

apt-get download $(apt-rdepends vim | grep -v "^ " | sed 's/debconf-2.0/debconf/g')

Then

sudo dpkg -i *

SSSD and Active Directory

· One min read

SSSD and Active Directory​

  1. install packages:
sudo apt install sssd-ad sssd-tools realmd adcli sssd-tools sssd libnss-sss libpam-sss adcli packagekit
  1. join domain
sudo realm discover -v $DOMAIN
sudo realm join $DOMAIN
  1. edit /etc/sssd/sssd.conf
$ vim /etc/sssd/sssd.conf

[sssd]
domains = ad1.example.com
config_file_version = 2
services = nss, pam

[domain/ad1.example.com]
default_shell = /bin/bash
krb5_store_password_if_offline = True
cache_credentials = True
krb5_realm = AD1.EXAMPLE.COM
realmd_tags = manages-system joined-with-adcli
id_provider = ad
fallback_homedir = /home/%u@%d
ad_domain = ad1.example.com
use_fully_qualified_names = True
ldap_id_mapping = True
access_provider = ad

# the following is not shown in ubuntu documentation,
# but is necessary for version after 22
ad_gpo_ignore_unreadable = True
ad_gpo_access_control = permissive
  1. automatically create home directory

sudo pam-auth-update --enable mkhomedir
  1. check
getent passwd $USERNAME@$DOMAIN
  1. login
$ sudo login

ad-client login: $USERNAME@$DOMAIN
Password:
Welcome to Ubuntu 20.04 LTS (GNU/Linux 5.4.0-24-generic x86_64)
...
Creating directory '/home/john@ad1.example.com'.
john@ad1.example.com@ad-client:~

Member Server in an Active Directory Domain

· One min read

Member Server in an Active Directory Domain​

  1. Install packages:
sudo apt install realmd samba libnss-winbind samba-common-bin libpam-winbind winbind
  1. Edit /etc/resolv.conf
nameserver # BD server ip address
  1. find realm
sudo realm discover
  1. Realm join
sudo realm join -v --membership-software=samba --client-software=winbind $DOMAIN REALM
  1. edit /etc/nsswitch.conf
passwd:         files systemd winbind
group:          files systemd winbind
  1. automatically create home directory
sudo pam-auth-update --enable mkhomedir
  1. see references for more detail