Wht is banner grabing?

Ap server ke info nikaltae ho.Os version wagaira..
Ap jb server ke info nikal loge tou further exploit kar saktae ho.
U need netcat.
Phelay port find karo.Netcat se kar saktae ho.But i recomend nmap.
Then port aur ip se karo exploit.
Type some thng -v -n ip port