ssh without shell (non interactive)

/sbin/nologin is what you have to put instead of /bin/bash at the end of a user’s line in /etc/passwd file if you only want the user to be able to use your machine to do thing like SOCKS proxy but never be able to login to a shell.
for example:
somewhere out there you have a linux machine (LLL) with big bandwidth (Mbps) and you want to be able to browse the internet through it sometimes. you can do that by setting up a SOCKS proxy on your local machine and ssh tunneling it to LLL.
on LLL you must create a user (theuser) with password and /sbin/nologin as the shell.
supposed that LLL is located in USA and domain name is www.LLL.com and you are from a windows xp machine located in UK want to browse the internet as if you do it from LLL. first you have to get putty and then save it on c: then click start, run and write this c:putty.exe -N -D 8883 -C theuser@www.LLL.com then click ok, enter user and password when prompted.
next step is to setup your browser to use localhost port 8883 as the SOCKS proxy. with mozilla it should be at tools-options-advanced-network-settings.

now point your browser to www.whatismyip.com and you should be shown the ip of www.LLL.com