General¶

General, random and useful Linux-related config and things.

A good site to browse random commands and things: https://www.commandlinefu.com/

Apt & Yum Cheat Sheets¶

https://blog.packagecloud.io:

Apt Cheat Sheet

Yum Cheat Sheet

Yum¶

Clear Yum Cache¶

https://unix.stackexchange.com/questions/481993/tar-directory-and-exclude-multiple-subdirectories/481994

yum clean all

Nmap¶

https://phoenixnap.com/kb/nmap-scan-open-ports

# Scan a host
nmap www.hostname.com

# Scan a range
nmap 192.168.0.1-10

# Scan a subnet
nmap 192.168.0.1/24

# Scan a list of hosts
nmap -iL textlist.txt

# Scan a port
nmap -p 80 192.168.0.1

# Scan a range of ports
nmap -p 1-200 192.168.0.1

# Fast scan most common ports
nmap -F 192.168.0.1

# Scan all ports
nmap -p- 192.168.0.1

# Scan using TCP connect (takes longer but more likely to connect)
nmap -sT 192.168.0.1

# Scan default SYN scan (tests by performing only half the TCP handshake)
nmap -sS 192.168.0.1

# Scan UDP ports
nmap -sU -p 80,130,255 192.168.0.1

# Bypass host discovery (host discovery uses ping, but many firewalls don't respond to ping. This runs the test without waiting for ping response)
nmap -Pn -F 192.168.0.1

# Detect OS
nmap -A 192.168.0.1

# Scan for services that might be using different ports
nmap -sV 192.168.0.1

Rsync¶

https://ss64.com/bash/rsync.html

https://www.computerhope.com/unix/rsync.htm

# rsync without owner and group attributes
rsync -avP --no-o --no-g /mnt/data/share/ /mnt/server3/Backups/

# cronning rsync (https://unix.stackexchange.com/questions/392780/how-to-schedule-an-rsync-command)
crontab -e
  0 19 * * * root rsync -a src dest

# rsync showing progress (https://www.cyberciti.biz/faq/show-progress-during-file-transfer/)
rsync -P src dest

# rsync exclude stuff
rsync -avP --exclude 'file_or_dir' src/ dst/

# rsync exclude from source file list
cat excl-list.txt
  thisdir
  thatdir
  myfile.txt
rsync -av --exclude-from={excl-list.txt}

# stop rsync from bandwidth vreet (https://www.cyberciti.biz/faq/how-to-set-keep-rsync-from-using-all-your-bandwidth-on-linux-unix/)
rsync -avP --bwlimit=KBps
rsync -avP --bwlimit=1024 src/ dst/

# rsync specify multiple source dirs (https://unix.stackexchange.com/questions/368210/how-to-rsync-multiple-source-folders)
rsync -avP /src/one /src/two /src/etcetra /dst

Rsync Compare Directories¶

https://unix.stackexchange.com/questions/57305/rsync-compare-directories

rsync -nai --delete source destination | grep "^deleting "

Smartcl¶

https://unix.stackexchange.com/questions/39064/smartctl-on-external-hdd-inside-ide-to-usb-enclosure

smartctl -H -d sat /dev/sda

While Loop¶

https://stackoverflow.com/questions/1289026/syntax-for-a-single-line-while-loop-in-bash

while true; do foo; sleep 2; done

For Loop¶

https://unix.stackexchange.com/questions/103920/parallelize-a-bash-for-loop/103922

# Parellelize a for loop
for thing in a b c d e f g; do 
  task "$thing" &
done

Moving Files with Spaces¶

https://unix.stackexchange.com/questions/392393/bash-moving-files-with-spaces

while IFS= read -r file; do echo "$file"; done < files

IPv6¶

Disabling IPv6¶

https://itsfoss.com/disable-ipv6-ubuntu-linux/

nano /etc/sysctl.conf
  net.ipv6.conf.all.disable_ipv6=1
  net.ipv6.conf.default.disable_ipv6=1
  net.ipv6.conf.lo.disable_ipv6=1
sudo sysctl -p

Fstab¶

Automounting¶

# List all UUIDs of drives
blkid

# List all disks
fdisk -l

nano /etc/fstab
  UUID=05cdfcb3-90fc-40ec-8ff1-3324e3767b1d   /media/data ext4    defaults,nofail 0 0

Emergency Mode Bad Fstab¶

# Put SD card / HDD into another PC
nano /boot/cmdline.txt
  init=/bin/sh

# Put SD card / HDD back into original machine

# Mount FS (but not fstab)
mount -o remount,rw / –target /

# Modify fstab
nano /etc/fstab
  # modify what must be

# Put SD card / HDD into another PC
nano /boot/cmdline.txt
  # delete init=/bin/sh

# Put SD card / HDD back into original machine

Swap¶

https://www.digitalocean.com/community/tutorials/how-to-add-swap-space-on-ubuntu-20-04

sudo swapon --show
free -h
df -h
sudo fallocate -l 1G /swapfile
sudo chmod 600 /swapfile
sudo mkswap /swapfile
sudo swapon /swapfile
echo '/swapfile none swap sw 0 0' | sudo tee -a /etc/fstab

SSH Config¶

https://www.ssh.com/ssh/config/

https://www.openssh.com/legacy.html

Example:

cat ~/.ssh/config
  Host server
   LocalForward 2222 192.168.99.99:22
   User ubuntu
   Hostname 192.168.100.1
   IdentityFile ~/.ssh/server
  Host router
   User cisco
   Hostname 192.168.1.1
   IdentityFile ~/.ssh/router
   Ciphers aes256-cbc
  Host switch
   User cisco
   Hostname 192.168.33.2
   Ciphers aes256-cbc
   KexAlgorithms +diffie-hellman-group1-sha1

OpenSSL¶

# https://stackoverflow.com/questions/5244129/use-rsa-private-key-to-generate-public-key
# Generate public key from private
openssl rsa -in mykey.pem -pubout > mykey.pub

Disk Usage¶

# Human readable output
du -h mydir/

# Kilobytes
du -k mydir/

# Megabytes
du -m mydir/

# Which sub-dirs consume how much disk space:
du -h --max-depth=1 mydir/ | sort -hr

# List all items including files and dirs
du -ah mydir/

# Multiple dirs
du -h dir1/ dir2/

# Summary
du -sh

# Grand total of dirs
du -sch dir/

# Exclude:
du -sh --exclude='*.docx'

Order by Size¶

https://www.studytonight.com/forum/how-can-i-sort-du-h-output-by-size

du | sort -nr | cut -f2- | xargs du -hs

Formatting Disk¶

# List disks
df -h
fdisk -l

# Unmount disk to format
sudo umount /dev/sdc1

# vFAT, NTFS, EXT4, etc.:
sudo mkfs.vfat /dev/sdc1
sudo mkfs.ntfs /dev/sdc1
sudo mkfs.ext4 /dev/sdc1

ISO to Disk¶

sudo dd if=~/Downloads/ubuntu_something.iso of=/dev/diskN

Check SSL Certificate Expiry Date¶

https://www.cyberciti.biz/faq/find-check-tls-ssl-certificate-expiry-date-from-linux-unix/

echo | openssl s_client -servername www.calebsargeant.com -connect www.calebsargeant.com:443 | openssl x509 -noout -dates

Inodes¶

https://stackoverflow.com/questions/24671621/no-space-left-on-device

df -i

https://unix.stackexchange.com/questions/117093/find-where-inodes-are-being-used

{ find / -xdev -printf '%h\n' | sort | uniq -c | sort -k 1 -n; } 2>/dev/null

Mail¶

https://askubuntu.com/questions/12917/how-to-send-mail-from-the-command-line

Grep¶

# exclude nologin
grep -wv nologin /etc/passwd

# recursive lookups - https://stackoverflow.com/questions/1987926/how-do-i-grep-recursively
grep -r "texthere" .

Tail¶

## https://stackoverflow.com/questions/39615142/bash-get-last-line-from-a-variable
# Get last line
tail -n1

SFTP¶

Pass Variable into SFTP¶

https://unix.stackexchange.com/questions/228859/how-do-i-pass-a-variable-into-sftp

sftp -i key.pem -b - un@server <<< "get /some/path/with/$yr"

Curl¶

Uploading Files¶

https://ec.haxx.se/usingcurl/usingcurl-uploads

curl https://EXAMPLE \
  -F 'one=sometext' \
  -F 'two=someothertext' \
  -F 'three=somemoretext' \
  -F 'doc=@/Users/caleb/Documents/Test.docx; type=application/vnd.openxmlformats-officedocument.wordprocessingml.document'

Curl to SFTP¶

https://stackoverflow.com/questions/31730476/curl-fails-on-sftp-password-authentication

curl -v --insecure --user username:urlencodedPassword sftp://somedomain.com

TCPDump¶

https://danielmiessler.com/study/tcpdump/

https://serverfault.com/questions/1025292/how-to-specify-both-ip-address-and-port-in-tcpdump

Get all https traffic:

tcpdump -nnSX port 443

Get just port 443

tcpdump port 443

Get from specific source:

tcpdump src 10.3.0.4

Dump from an interface:

tcpdump -i eth0

Putting it all together:

tcpdump -i enp1s9 dst 192.168.6.1 and src 192.168.6.2 and src port 80

Find¶

https://askubuntu.com/questions/123305/how-to-find-a-folder-on-my-server-with-a-certain-name

find ~ -name foldername -type d

https://stackoverflow.com/questions/5905054/how-can-i-recursively-find-all-files-in-current-and-subfolders-based-on-wildcard

find . -name "foo*"

https://www.howtogeek.com/howto/ubuntu/delete-files-older-than-x-days-on-linux/

find /path/to/files* -mtime +5 -exec rm {} \;

Screen¶

Using Screen¶

https://linuxize.com/post/how-to-use-linux-screen/

# Create screen called caleb
screen -S caleb

# Go into screen called caleb
screen -r -d caleb

List Running Sessions¶

https://stackoverflow.com/questions/537942/how-to-list-running-screen-sessions

screen -ls
ls -laR /var/run/screen

Kill a Detached Session¶

https://stackoverflow.com/questions/1509677/kill-detached-screen-session

screen -X -S [session # you want to kill] quit

Detatch Session¶

https://www.tecmint.com/screen-command-examples-to-manage-linux-terminals/#:~:text=Leaving%20Screen%20Terminal%20Session,K%E2%80%9D%20to%20kill%20the%20screen.

Ctrl-A d

Generating SSH Keys¶

https://askubuntu.com/questions/311558/ssh-permission-denied-publickey

### ON THE CLIENT

# Generate a public key on the client
ssh-keygen -t rsa -b 4096

### Output
#Generating public/private rsa key pair.
#Enter file in which to save the key (/home/ubuntu/.ssh/id_rsa):
#Enter passphrase (empty for no passphrase):
#Enter same passphrase again:
#Your identification has been saved in /home/ubuntu/.ssh/id_rsa.
#Your public key has been saved in /home/ubuntu/.ssh/id_rsa.pub.
#The key fingerprint is:
#SHA256:random

# Copy public key to server (you will be required to authenticate)
ssh-copy-id ubuntu@10.0.2.12

### Output
# /usr/bin/ssh-copy-id: INFO: Source of key(s) to be installed: "/home/ubuntu/.ssh/id_rsa.pub"
# /usr/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed
# /usr/bin/ssh-copy-id: INFO: 1 key(s) remain to be installed if you are prompted now it is to install the new keys
# ubuntu@10.0.2.12's password:

# Number of key(s) added: 1

# Now try logging into the machine, with:   "ssh 'ubuntu@10.0.2.12'"
# and check to make sure that only the key(s) you wanted were added.

# You can add IdentitiesOnly yes to ensure ssh uses the IdentityFile and no other keyfiles during authentication, which can cause issues and is not a good practice.
vim ~/.ssh/config
  Host SERVERNAME
  Hostname ip-or-domain-of-server
  User USERNAME
  PubKeyAuthentication yes
  IdentityFile ./path/to/key

Sudo without Password¶

# DO NOT MAKE A MISTAKE
visudo
    %sudo   ALL=(ALL:ALL) NOPASSWD:ALL

Compression¶

Gzip¶

https://linuxize.com/post/how-to-unzip-gz-file/

gzip -d file.gz

Zip¶

yum -y install zip unzip
zip -9 -r <zip file> <folder name>
unzip file.zip

Bunzip¶

bunzip2 myfile.bz2
tar xjvf myfile.tar.bz2

Tar¶

A good source for tar commands https://www.freecodecamp.org/news/tar-in-linux-example-tar-gz-tar-file-and-tar-directory-and-tar-compress-commands/.

.tar

tar -cvf myarchive.tar mydirectory/
tar -xvf mystuff.tar

.tar.gz

tar -czvf myarchive.tgz mydirectory/
tar -xzvf mystuff.tgz

Tar to CIFS:

# Backup the MySQL database
mysqldump zabbix > backup.sql

# Install cifs-utils
apt-get install cifs-utils

# Create mountpoint dir
mkdir /mnt/data

# Mount the share
mount -t cifs //10.10.10.10/share /mnt/data -o user=administrator

# Archive Zabbix config & DB
tar cfzv backup.tar.gz /etc/zabbix/ backup.sql

# Copy to share
cp backup.tar.gz /mnt/data/

Tar exclude:

https://unix.stackexchange.com/questions/32845/tar-exclude-doesnt-exclude-why

https://unix.stackexchange.com/questions/481993/tar-directory-and-exclude-multiple-subdirectories/481994

tar --exclude='./folder' --exclude='./upload/folder2' \
  -zcvf /backup/filename.tgz .

https://unix.stackexchange.com/questions/481993/tar-directory-and-exclude-multiple-subdirectories

tar -czvf /location/my.tar.gz --exclude='/dir1' --exclude='/dir2' /dir/to/tar

PDF to CSV¶

https://github.com/tabulapdf/tabula-java/releases

TABULARNAME=tabula-1.0.3-jar-with-dependencies.jar
YEAR=2019
MONTH=08
java -jar ./$TABULARNAME -b ./$YEAR/$MONTH -t -p all

Installing GUI on CentOS¶

yum groupinstall "Desktop" "Desktop Platform" "X Window System" "Fonts"

List Samba Users¶

pbdedit -L

Open Webpage on Mac¶

open -a "Google Chrome" index.html

Running FSCK Manually¶

You get a message: (or something similar) /dev/mapper/vg_fedora1530-lv-home: UNEXPECTED INCONSISTENCY: RUN fsck MANUALLY (i.e., without -a or -p options) Try the following: 1. Type the following commands: umount /dev/sda* fsck /dev/sda1 -f -y -a (see http://www.computerhope.com/unix/fsck.htm for syntax of fsck)

Nginx¶

https://stackoverflow.com/questions/18587638/how-do-i-restart-nginx-only-after-the-configuration-test-was-successful-on-ubunt

sudo nginx -t && sudo nginx -s reload

Xen¶

Manually Starting¶

xm list
cd /etc/xen/
ls
xm create <vm-name>
ping <vm-name>
xm list

Install Xen¶

yum install xen virt-manager kernel-xen
chkconfig xend on
reboot

Mount CD for Image of OS¶

mkdir /media/cdrom
mount -t <name_of_iso> -o ro /dev/cdrom /media/cdrom

Install VM¶

virt-install --prompt (yes centos 512 /home/vm/centos /media/cdrom)

Launch VM to Create Virtual OS¶

# NOTE to exit startx press ctrl,alt,bkspce
startx
virt-manager

Skel Terminal Colours¶

mv .bashrc .bashrc.bak
cp /etc/skel/.bashrc .bashrc
nano .bashrc
# uncomment this:
force_color_prompt=yes
# add this to the bottom of the file
[[ -s "$HOME/.rvm/scripts/rvm" ]] && source "$HOME/.rvm/scripts/rvm"
. .bashrc

Move a File Starting with Dash¶

# https://www.cyberciti.biz/faq/linuxunix-move-file-starting-with-a-dash/
mv -- '--bar.txt' /path/to/dest

LFTP¶

https://linuxconfig.org/lftp-tutorial-on-linux-with-examples

Rename a File to a Filename with Date¶

cp <name_of_file> <new_name_of_file>.`date -I`

Checking CPU Architecture¶

uname -i

Checking Uptime¶

uptime

Crontab different editor¶

https://www.linux.org/threads/set-your-default-editor-for-things-like-crontab-visudo-etc.5046/

export EDITOR="nano"
export VISUAL="nano"

TigerVNC¶

yum install vnc vnc-server tigervnc-server xterm
yum groupinstall Desktop

useradd <UserNameHere>
passwd <UserNameHere>

vi /etc/sysconfig/vncservers
  VNCSERVERS="1:<user1> 2:<user2> 3:<user3>"
  VNCSERVERARGS[1]="-geometry 640x480"
  VNCSERVERARGS[2]="-geometry 640x480"
  VNCSERVERARGS[3]="-geometry 800x600"

# Remember to delete the nonsense after: <resolution>"

su - <username>
vncpasswd
service vncserver start

# To connect to a Windows machine, install tiger-vnc on the Windows machine and enable Remote Desktop. Allow RDP 3389 through firewall.

Old School LAMP¶

Features¶

Apache (hosts the website)
MySQL (Database server)
PHP (hypertext processor)
Joomla (creates the website. Dependant on PHP and MYSQL)

Installation¶

My SQL Server 5.0 (server & client)

yum install mysql mysql-server
chkconfig --levels 235 mysqld on
/etc/init.d/mysqld start
mysql_secure_installation

Apache 2

(http://xxx.xxx.xxx) (Apache's default document root is /var/www/html on CentOS, and the configuration file is /etc/httpd/conf/httpd.conf. Additional configurations are stored in the /etc/httpd/conf.d/ directory)

yum install httpd
chkconfig --levels 235 httpd on
/etc/init.d/httpd start

PHP5

yum install php
/etc/init.d/httpd restart
vi /var/www/html/info.php

MySQL Support for PHP5

(http://xxx.xxx.xxx.xxx/info.php)

yum search php
yum install php-mysql php-gd php-imap php-ldap php-mbstring php-odbc php-pear php-xml phpxmlrpc
yum install php-pecl-apc
/etc/init.d/httpd restart

phpMyAdmin

(http://xxx.xxx.xxx.xxx/phpmyadmin/)

rpm --import http://dag.wieers.com/rpm/packages/RPM-GPG-KEY.dag.txt

# 64-bit:
yum install http://pkgs.repoforge.org/rpmforge-release/rpmforge-release-0.5.2-2.el6.rf.x86_64.rpm

# 32-bit
yum install http://pkgs.repoforge.org/rpmforge-release/rpmforge-release-0.5.2-2.el6.rf.i686.rpm

yum install phpmyadmin
vi /etc/httpd/conf.d/phpmyadmin.conf
  #
  # Web application to manage MySQL
  #
  #<Directory "/usr/share/phpmyadmin">
  # Order Deny,Allow
  # Deny from all
  # Allow from 127.0.0.1
  #</Directory>
  Alias /phpmyadmin /usr/share/phpmyadmin
  Alias /phpMyAdmin /usr/share/phpmyadmin

vi /usr/share/phpmyadmin/config.inc.php
  [...]
  /* Authentication type */
  $cfg['Servers'][$i]['auth_type'] = 'http';
  [...]

/etc/init.d/httpd restart

Joomla!

If you are installing LAMP without Joomla then skip all the commands that have anything to do with Joomla.

cd /tmp
yum install wget
wget joomlacode.org/gf/download/frsrelease/17715/77262/Joomla_2.5.8-Stable-Full_Package.zip
mkdir /tmp/joomla
unzip Joomla_2.5.8-Stable-Full_Package.zip /tmp/joomla/
mv /tmp/joomla/* /var/www/html/
service mysqld start; chkconfig mysqld on
/usr/bin/mysql_secure_installation
yum --enablerepo=epel install phpmyadmin

vi /etc/httpd/conf.d/phpMyAdmin.conf
  Allow from 127.0.0.1 xxx.xxx.xxx.xxx/24

iptables -I INPUT -p tcp --dport http -j ACCEPT ; service iptables save ; service iptables restart

vi /etc/php.ini
  output_buffering=Off

touch /var/www/html/configuration.php
chmod 666 /var/www/html/configuration.php
service httpd start; chkconfig httpd on

mysql -u root -p
  create database <db_name_here>
  create user 'root'@'localhost' identified by '<password_here>';
  grant all privileges on <db_name_here>.* to root@localhost;
  show grants for 'root'@'localhost';

Open up a web browser and type in http://xxx.xxx.xxx. Follow the wizard. REMEMBER TO COPY CONFIGURATION TEXT TO /var/www/html/configuration.php. rm -rf /var/www/html/installation/ You can access the server by going to a browser and typing http://xxx.xxx.xxx/administrator.

Git Server¶

On the Server¶

Installing Git

yum install git-core

Configuring the git group

groupadd git

For a new user:

useradd -G git <username>
passwd <username>
id <username>

For an existing user:

usermod -a -G git <username>
id <username>

Configuring the Git Server Repository

mkdir /path/to/gits
cd /path/to/gits
mkdir project.git
cd project.git
git init --bare --shared=group
sudo chmod -R g+ws *
sudo chgrp -R git *

Configuring the Git Hook for Web code

mkdir /var/www/html/project
cd /path/to/gits/project.git
vi /hooks/post-recieve
#!/bin/sh
GIT_WORK_TREEE=/var/www/html/project git checkout -f
chmod +x hooks/post-receive
chown -R git:git *

On the Client's Machine¶

Download and install: https://git-scm.com/download/win

mkdir /path/to/gits
cd /path/to/gits
mkdir project.git
cd project.git
git init
git remote add web ssh://<HostnameOrIP>/full/path/to/project.git
git add README
git commit -m "Initial Import"
git push web +master:refs/heads/master

Then open Firefox, go to \<HostnameOrIP>/project Then in future: git push web

Please note that you wont see any files on the server, because it is a bare repository and therefore the files are protected. You can create a Git Hook to expose the bare repository's files in a different directory (useful for web code). Use git clone \<hostname>/path/to/gits to clone an existing server repository.

Age of System¶

https://serverfault.com/questions/221377/how-to-determine-the-age-of-a-linux-system-since-installation

ubuntu@server:~$ sudo tune2fs -l /dev/sda2 | grep created
Filesystem created:       Mon Sep  7 06:49:22 2020

List all Services¶

https://www.tecmint.com/list-all-running-services-under-systemd-in-linux/

systemctl list-units --type=service
systemctl --type=service

Temporary Failure in Name Resolution¶

https://stackoverflow.com/questions/53687051/ping-google-com-temporary-failure-in-name-resolution

sudo systemctl disable systemd-resolved.service
sudo systemctl stop systemd-resolved.service
sudo rm /etc/resolv.conf
echo "nameserver 1.1.1.1" > /etc/resolv.conf
echo "nameserver 1.0.0.3" >> /etc/resolv.conf

Change Hosname¶

https://www.cyberciti.biz/faq/ubuntu-20-04-lts-change-hostname-permanently/

sudo hostnamectl set-hostname SERVERNAME
nano /etc/hosts

Google Authenticator¶

CentOS 7¶

# Update and Upgrade
yum -y update && yum -y upgrade

# Install FreeRADIUS
yum install freeradius freeradius-utils

# Install nano
yum install nano

# Make root the user
nano /etc/raddb/radiusd.conf

user = root
group = root

# Enable PAM
nano /etc/raddb/sites-enabled/default

# Pluggable Authentication Modules.
pam

ln -s /etc/raddb/mods-available/pam /etc/raddb/mods-enabled/pam

# Add the RADIUS clients
nano /etc/raddb/clients.conf

client asa {
ipaddr = 10.145.16.3
secret = supersecuresecret
nas_type = cisco
}

# Change auth type
nano /etc/raddb/users

DEFAULT Group == "disabled", Auth-Type := Reject

Reply-Message = "Your account has been disabled."

DEFAULT Auth-Type := PAM

# Reload radiusd
service radiusd restart

# Test RADIUS, look for any errors
radiusd -X

# Test RADIUS without LDAP or Google Auth
useradd raduser
passwd raduser

radtest raduser Password1 localhost 0 testing123

# Installing tools to add box to domain
yum install sssd realmd adcli oddjob oddjob-mkhomedir sssd samba-common-tools

# Make computer join the domain
realm join corp.domain.com -U caleb.sargeant

# Configure SSSD
nano /etc/sssd/sssd.conf

ad_domain = corp.domain.com
krb5_realm = CORP.DOMAIN.COM
realmd_tags = manages-system joined-with-samba
cache_credentials = True
id_provider = ad
krb5_store_password_if_offline = True
default_shell = /bin/bash
ldap_id_mapping = True
use_fully_qualified_names = False
fallback_homedir = /home/%u
access_provider = simple
simple_allow_groups = test-group

# Allow only users part of test-group to auth with radius server
realm permit -g test-group

### SSH into the box with caleb.sargeant@ct-googleauth - not needed anymore, become the user via su only

# Reload radiusd & SSSD
service radiusd restart
service sssd restart

# Test RADIUS with LDAP, without Google Auth
radiusd -X

radtest caleb.sargeant <Password> localhost 0 testing123

# Install stuff for Google Authenticator
yum install pam-devel make gcc-c++ git wget

# Installing Google Authenticator
cd /tmp
wget https://dl.fedoraproject.org/pub/epel/7/x86_64/Packages/g/google-authenticator-1.04-1.el7.x86_64.rpm
rpm -i google-authenticator-1.04-1.el7.x86_64.rpm

# Configuring Google Authenticator for a user
su - caleb.sargeant
google-authenticator
### say y for everything, backup the numbers!

# Add Google Authenticator to PAM
nano /etc/pam.d/radiusd
#%PAM-1.0
auth requisite pam_google_authenticator.so forward_pass
auth required pam_sss.so use_first_pass
account required pam_nologin.so
account include password-auth
session include password-auth

# Test RADIUS with LDAP and Google Auth
radtest caleb.sargeant <Password><GoogleAuthCode> localhost 0 testing123

# Disable SELinux
nano /etc/selinux/config
SELINUX=disabled

# Configuring firewall
firewall-cmd --get-default-zone
firewall-cmd --zone=public --list-all
firewall-cmd --get-services | grep rad
firewall-cmd --permanent --zone=public --add-service=radius
firewall-cmd --reload

Cisco AnyConnect Connection¶

The below guide shows one how to connect to the VPN using one's OTP. The connection is exactly the same as the previous VPN connection.

To connect to the VPN using MFA, first connect to your region.

google authenticator

Select the MFA Group.

google authenticator

Enter your credentials. Once you have finished typing in your password, enter your TOTP. In this example, I will be using Google Authenticator on Android. The format is YOURPASSWORD-OTP (without the "-").

google authenticator

You will be connected to the VPN as per normal.

google authenticator

LDAP Authentication¶

Public Key Authentication¶

First, on the host, reset the password of ubuntu & root

ubuntu@hostname:~$ sudo su -
root@hostname:~# passwd ubuntu
root@hostname:~# passwd root

Modify the sudoers file, so that we don't have type in the password to become root. DO NOT make a mistake here.

visudo
  %sudo   ALL=(ALL:ALL) NOPASSWD:ALL

On your laptop, copy the sshkey to the host

name.surname@MacBookPro:~$ sudo ssh-copy-id -i key.pub ubuntu@hostname

You can now log into the host using ubuntu & the key.

SSSD¶

Modify the sudoers

# Add Infrasturcture Team to Sudoers
nano /etc/sudoers.d/ad-ldap
  %Infrastructure\ Team ALL=(ALL:ALL) NOPASSWD:ALL

# Change permissions on sudoers file to Owner & Group readable only
chmod 440 /etc/sudoers.d/ad-ldap

Install SSSD & Related Tools

apt-get install samba-common sssd sssd-tools realmd adcli oddjob oddjob-mkhomedir libnss-sss libpam-sss adcli -y

Join the domain

sudo realm join corp.example.com -U caleb.sargeant --install=/

SSSD Configuration

# Add or modify the below
nano /etc/sssd/sssd.conf
  use_fully_qualified_names = False
  fallback_homedir = /home/%u
  skel_dir = /etc/skel
  homedir_umask = 000
  override_homedir = /home/%u
  simple_allow_groups = Infrastructure\ Team

Restart SSSD

service sssd restart

You can now log in to the host using your domain credentials

To add Duo Authentication push notifications, see here.

Gcloud¶

Installation¶

https://stackoverflow.com/questions/31037279/gcloud-command-not-found-while-installing-google-cloud-sdk

curl https://sdk.cloud.google.com | bash
# The next line updates PATH for the Google Cloud SDK.
source '[path-to-my-home]/google-cloud-sdk/path.bash.inc'
# The next line enables bash completion for gcloud.
source '[path-to-my-home]/google-cloud-sdk/completion.bash.inc'

Find the PID Using Port¶

https://unix.stackexchange.com/questions/106561/finding-the-pid-of-the-process-using-a-specific-port

sudo ss -lptn 'sport = :80'
sudo netstat -nlp | grep :80
sudo lsof -n -i :80 | grep LISTEN

Unmounting a Busy Device¶

https://stackoverflow.com/questions/7878707/how-to-unmount-a-busy-device

umount -l /PATH/OF/BUSY-DEVICE
umount -f /PATH/OF/BUSY-NFS (NETWORK-FILE-SYSTEM)

Ubuntu Resize Logical Volume¶

https://askubuntu.com/questions/1269493/ubuntu-server-20-04-1-lts-not-all-disk-space-was-allocated-during-installation

vgdisplay
lvextend -l +100%FREE /dev/mapper/ubuntu--vg-ubuntu--lv
resize2fs /dev/mapper/ubuntu--vg-ubuntu--lv

Wget¶

Download a list of files¶

https://stackoverflow.com/questions/40986340/how-to-wget-a-list-of-urls-in-a-text-file

wget -i text_file.txt

Cat & Tac¶

https://stackoverflow.com/questions/742466/how-can-i-reverse-the-order-of-lines-in-a-file

# Flip a file into another
tac a.txt > b.txt

WC¶

https://www.baeldung.com/linux/bash-count-lines-in-file#:~:text=3.-,wc,the%20name%20of%20the%20file.

# Get the number of lines in a file
wc -l file.txt

Decrypt GPG¶

https://www.cyberciti.biz/tips/linux-how-to-encrypt-and-decrypt-files-with-a-password.html

gpg -d myfinancial.info.txt.gpg

Forget GPG Invalid Password¶

https://emacs.stackexchange.com/questions/52837/how-to-force-emacs-or-pinentry-to-forget-wrong-gpg-password

gpgconf --kill gpg-agent

List DNS Servers Ubuntu¶

https://askubuntu.com/questions/152593/command-line-to-list-dns-servers-used-by-my-system

nmcli device show <interfacename> | grep IP4.DNS
systemd-resolve --status

Install WireGuard VPN Client¶

https://serverspace.io/support/help/how-to-install-wireguard-vpn-client-on-ubuntu-linux/

sudo apt-get install wireguard
cd /etc/wireguard
wg genkey | tee private.key | wg pubkey > public.key
sudo nano /etc/wireguard/wg0.conf
  [Interface]
  PrivateKey = <contents-of-client-privatekey>
  Address = 10.0.0.1/24
  PostUp = iptables -A FORWARD -i wg0 -j ACCEPT; iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
  PostDown = iptables -D FORWARD -i wg0 -j ACCEPT; iptables -t nat -D POSTROUTING -o eth0 -j MASQUERADE
  ListenPort = 51820

  [Peer]
  PublicKey = <contents-of-server-publickey>
  AllowedIPs = 10.0.0.2/32

sudo wg-quick up wg0
sudo wg show

Install Docker on Amazon Linux 2¶

https://www.cyberciti.biz/faq/how-to-install-docker-on-amazon-linux-2/

yum install docker
usermod -a -G docker ec2-user
newgrp docker
yum install python3-pip
pip3 install docker-compose
systemctl enable docker.service