linux – Page 21

Log in with an SSH private key on Linux

October 31, 2018

chmod 600 deployment_key.txt

ssh -i deployment_key.txt [email protected]

References
https://support.rackspace.com/how-to/logging-in-with-an-ssh-private-key-on-linuxmac/

Start and Stop Softether from command line on linux

October 26, 2018

extute ip route show and compare route table before and after connecting to the vpn server to get all required addresses

start.sh

#!/bin/sh

[ "$UID" -eq 0 ] || exec sudo "$0" "$@"

vpnclient start
sleep 2s
vpncmd localhost /client /CMD AccountConnect [ConnectionName]
dhclient [VPN_Adapter]
ip route add [VPN_Server_IP]/32 via [Gateway_Address] dev [Network_Device_Name]
ip route del default via [Gateway_Address] dev [Network_Device_Name]

#!/bin/sh

[ "$UID" -eq 0 ] || exec sudo "$0" "$@"

vpnclient start
sleep 2s
vpncmd localhost /client /CMD AccountConnect GE
dhclient vpn_vpn
ip route add 145.245.93.56/32 via 192.168.1.1 dev wlp3s0
ip route del default via 192.168.1.1 dev wlp3s0

stop.sh

#!/bin/sh

[ "$UID" -eq 0 ] || exec sudo "$0" "$@"

vpncmd localhost /client /CMD AccountDisconnect GE
vpnclient stop
ip route del default via 192.168.30.1 dev vpn_vpn
ip route del 145.245.93.56 via 192.168.1.1 dev wlp3s0 
ip route del 192.168.30.0/24 dev vpn_vpn proto kernel scope link src
ip route add default via 192.168.1.1 dev wlp3s0 proto dhcp metric 600
echo 'nameserver 8.8.8.8' > /etc/resolv.conf
echo 'nameserver 8.8.4.4' >> /etc/resolv.conf

References
https://pupli.net/2016/09/19/how-to-setup-softether-in-ubuntu/

Request root privilege from within a script in Bash

October 26, 2018

[ "$UID" -eq 0 ] || exec sudo "$0" "$@"

References
https://askubuntu.com/questions/746350/request-root-privilege-from-within-a-script/748362
https://unix.stackexchange.com/questions/28791/prompt-for-sudo-password-and-programmatically-elevate-privilege-in-bash-script
https://stackoverflow.com/questions/3976362/bash-scripts-requiring-sudo-password

Write data to text file using bash/shell scripting

October 26, 2018

You can redirect the output of a command to a file:

cat file > copy_file

or append to it

cat file >> copy_file

If you want to write directly the command is echo ‘text’

echo 'Hello World' > file

# possibility 1:
echo "line 1" >> greetings.txt
echo "line 2" >> greetings.txt

# possibility 2:
echo "line 1
line 2" >> greetings.txt

# possibility 3:
cat <<EOT >> greetings.txt
line 1
line 2
EOT

References
https://stackoverflow.com/questions/11162406/open-and-write-data-to-text-file-using-bash-shell-scripting
https://unix.stackexchange.com/questions/77277/how-to-append-multiple-lines-to-a-file

Set Up Time Synchronization on Ubuntu with ntpd

October 17, 2018

Though timesyncd is fine for most purposes, some applications that are very sensitive to even the slightest perturbations in time may be better served by ntpd, as it uses more sophisticated techniques to constantly and gradually keep the system time on track.

sudo timedatectl set-ntp no

timedatectl

sudo apt-get install ntp

sudo ntpq -p

References

https://www.digitalocean.com/community/tutorials/how-to-set-up-time-synchronization-on-ubuntu-16-04

Kill a nohup process on Linux

October 17, 2018

nohup my_command > my.log 2>&1 &
echo $! > save_pid.txt

kill -9 `cat save_pid.txt`
rm save_pid.txt

References

https://stackoverflow.com/questions/17385794/how-to-get-the-process-id-to-kill-a-nohup-process

Extra Repositories for Ubuntu Server 18.04

October 16, 2018

/etc/apt/sources.list

deb http://archive.ubuntu.com/ubuntu bionic universe multiverse
deb-src http://archive.ubuntu.com/ubuntu bionic universe multiverse

deb http://us.archive.ubuntu.com/ubuntu/ bionic universe
deb-src http://us.archive.ubuntu.com/ubuntu/ bionic universe
deb http://us.archive.ubuntu.com/ubuntu/ bionic-updates universe
deb-src http://us.archive.ubuntu.com/ubuntu/ bionic-updates universe

deb http://us.archive.ubuntu.com/ubuntu/ bionic multiverse
deb-src http://us.archive.ubuntu.com/ubuntu/ bionic multiverse
deb http://us.archive.ubuntu.com/ubuntu/ bionic-updates multiverse
deb-src http://us.archive.ubuntu.com/ubuntu/ bionic-updates multiverse

deb http://security.ubuntu.com/ubuntu bionic-security universe
deb-src http://security.ubuntu.com/ubuntu bionic-security universe
deb http://security.ubuntu.com/ubuntu bionic-security multiverse
deb-src http://security.ubuntu.com/ubuntu bionic-security multiverse

References

https://help.ubuntu.com/lts/serverguide/configuration.html.en

How to change timezone on Ubuntu 18.04 Bionic Beaver Linux

October 16, 2018

timedatectl list-timezones

sudo timedatectl set-timezone Asia/Tehran

Check if time is correct :

date

Set to UTC

sudo dpkg-reconfigure tzdata

References

https://linuxconfig.org/how-to-change-timezone-on-ubuntu-18-04-bionic-beaver-linux
https://www.cyberciti.biz/faq/howto-set-date-time-from-linux-command-prompt/
https://askubuntu.com/questions/138423/how-do-i-change-my-timezone-to-utc-gmt

Set Up SSH Keys on Ubuntu

October 13, 2018

Create the RSA Key Pair

ssh-keygen -t rsa -b 4096 -C "[email protected]"

Copy the Public Key to Ubuntu Server

cat ~/.ssh/id_rsa.pub | ssh username@remote_host "mkdir -p ~/.ssh && touch ~/.ssh/authorized_keys && chmod -R go= ~/.ssh && cat >> ~/.ssh/authorized_keys"

or Copying Public Key Manually

To display the content of your id_rsa.pub key, type this into your local computer:

cat ~/.ssh/id_rsa.pub

You will see the key’s content, which should look something like this:

ssh-rsa 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 demo@test

make sure the ~/.ssh directory exists.This command will create the directory if necessary, or do nothing if it already exists:

mkdir -p ~/.ssh

Now, you can create or modify the authorized_keys file within this directory. You can add the contents of your id_rsa.pub file to the end of the authorized_keys file, creating it if necessary, using this command:

echo public_key_string >> ~/.ssh/authorized_keys

Finally, we’ll ensure that the ~/.ssh directory and authorized_keys file have the appropriate permissions set:

chmod -R go= ~/.ssh

or Copy using ssh-copy-id

ssh-copy-id [email protected]
ssh-copy-id [email protected] -p 22000
ssh-copy-id -i id_rsa.pub -p 22000 "[email protected]"

use -i identity_file for other identities

Authenticate to Ubuntu Server Using SSH Keys

ssh username@remote_host

Disable Password Authentication on your Server

sudo nano /etc/ssh/sshd_config

PasswordAuthentication no

sudo systemctl restart ssh

Convert private key to putty

puttygen keyname -o keyname.ppk

ssh “permissions are too open” error

Keys need to be only readable by you:

chmod 400 ~/.ssh/id_rsa

If Keys need to be read-writable by you:

chmod 600 ~/.ssh/id_rsa

References
https://www.digitalocean.com/community/tutorials/how-to-set-up-ssh-keys-on-ubuntu-1604
https://haydenjames.io/how-to-convert-openssh-keys-to-putty-ppk-on-linux-with-puttygen/
https://help.github.com/en/articles/generating-a-new-ssh-key-and-adding-it-to-the-ssh-agent
https://stackoverflow.com/questions/9270734/ssh-permissions-are-too-open-error

How to disable baloo from indexing files on KDE

September 18, 2018

balooctl disable

balooctl status

nano ~/.config/baloofilerc

[Basic Settings]
   Indexing-Enabled=false

References
https://community.kde.org/Baloo/Configuration
https://bbs.archlinux.org/viewtopic.php?id=193169