For safety purpose, you can create a user without login for SSH tunneling.

Such user won’t have access to login the system and don’t have a home folder either. The only thing this user can do is changing the login password.

Commands to create a restricted user for SSH tunneling:

#Create user
useradd -M -s /sbin/nologin -n username

#Modify password
passwd username

#Remove the user
userdel -r username