对于user用户，登录SSH后不可使用端口转发，而且只能访问/bin/reshell这个Shell程序，不可以运行其他程序。
对于netadmin用户，登录SSH后不可以使用某些命令（Bash Shell）。

我记得/etc/passwd里面可以指定用户shell来着？不过貌似是不管什么方式登录，都是那个shell

參閱

1. http://askubuntu.com/questions/48129/ho ... forwarding
How to create a restricted SSH user for port forwarding?
The new user must not be able to:
execute shell commands
access files or upload files to the server
use the server as proxy (e.g. webproxy)
access local services which were otherwise not publicly accessible due to a firewall
kill the server

2. http://cybermashup.com/2013/05/14/restr ... e-command/
Restrict SSH logins to a single command