vtysh is integrated shell of Zebra software.
To use vtysh please specify --enable-vtysh to configure script. To use PAM for authentication use --with-libpam option to configure script.
vtysh only searches /usr/local/etc path for vtysh.conf which is the vtysh configuration file. Vtysh does not search current directory for configuration file because the file includes user authentication settings.
Currently, vtysh.conf has only one command.
!
username foo nopassword
!
With this set, user foo does not need password authentication for user vtysh. With PAM vtysh uses PAM authentication mechanism.
If vtysh is compiled without PAM authentication, every user can use vtysh without authentication.