Month: April 2020

Sudo user in Debian

Install the “sudo” Command
You need to run this command as root user:

user@debian:~$ su -
Password:
root@debian:~ # apt-get install sudo

Create a new user account.

#/usr/sbin/adduser admin

Add the user to the sudo group; By default on Debian systems, members of the group sudo are granted with sudo access. To add a user to the sudo group use the usermod command:

#usermod -aG sudo admin

Check the sudo access

#id admin
uid=1001(admin) gid=1001(admin) groups=1001(admin),27(sudo)

The user admin a member of sudo group now and to work as a root, every command must start with sudo (sudo reboot, sudo vim, sudo del, sudo mkdir, sudo……)

Error and solutions

admin@debian9:~$ sudo ifconfig
sudo: unable to resolve host (none)

Solutions

Insert hostname to /etc/hostname and /etc/hosts something like:

127.0.0.1    localhost.localdomain localhost
127.0.1.1    debian9

Disable IPv6 Debian 8

Disable IPv6 Debian 8 / Ubuntu

If can’t remove IPv6 on Debain 8 from hosting admin menu, It can disable through terminal

Debian-based/Ubuntu

sudo bash -c 'cat <<EOF >> /etc/sysctl.conf
net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
net.ipv6.conf.lo.disable_ipv6 = 1
EOF'

Configure SSH daemon to only listen over IPv4 by running the following:

echo 'AddressFamily inet' | sudo tee -a /etc/ssh/sshd_config

Then Reboot #reboot