Subject: Disallowing Certain Groups

From: "Karyl F. Stein" <[email-masked]>
Date: Mon, 8 Dec 1997 15:24:08 -0500 (EST)

Sorry if this is covered in a FAQ, or in server documentation, but I
didn't see it; pointers are welcome.

Here's my situation.  I am trying to setup a system where only certain
groups have access to the Internet.  Right now, I have a BSDI 3.1 system,
(running wu-ftpd), that contains a kernel modification which blocks 
socket() and bind() calls to all but those in the "Internet" group.  This
works fine.  For example, a user not in the group can log in to the FTP
server, but are unable to do anything, (get, put, ls, etc.) while users in
the group can.  I am trying to port this to Linux, and am having problems.
Users logged on the system are blocked as expected, but if they use the
FTP server, (logged in under their account), they have full functionality.

In other words, I only want users in a certain group to be able to log in
to their account via FTP, (actually, I don't mind if they can log in, but
I want to block any FTP transfers).  Is there an easy way to implement
this in wu-ftpd, (i.e. so I don't have to modify configuration files
whenever a new user is added, or moved in or out of the "Internet" group)?

Thanks,
Karyl F. Stein
[email-masked]