Add user to group which can access network interfaces

This worked for me:

sudo gpasswd -a yourusername netdev

Source

try adding the user to "netdev" group using usermod command instead of useradd command. Note that user must be an existing user. I have done this myself on Ubuntu 16.04 LTS and it works:

sudo usermod -a -G netdev <user>

after this command, check whether user got added by doing:

id <user>

if not added, try restarting/logging out and do above command (id) again

WARNING: do NOT omit '-a' in first command. Be careful

You can permit a user to run specific tool with root privilege by editing /etc/sudoers file. For example you can permit a non-root non-sudoer user to run only ifconfig command, so he/she can't access root privileged things like viewing /etc/shadow.

So, create a normal user (MYUSER in my example). Don't add it to root or sudo groups. Edit /etc/sudoers with your favorite editor like vim. Add this line under # User privilege specification:

MYUSER    ALL=(root) NOPASSWD :/sbin/ifconfig *

Then access ifconfig using sudo when logged in as MYUSER. For example:

sudo ifconfig eth0 down 

Replace ifconfig in this answer with any tool you want like tcpdump, tshark, etc.

Reference is here.