Xref: utzoo comp.bugs.sys5:910 comp.unix.wizards:15826
Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!lll-winken!uunet!ingr!b11!linwood
From: linwood@b11.ingr.com (Linwood Varney)
Newsgroups: comp.bugs.sys5,comp.unix.wizards
Subject: Re: Use of /etc/dialups and /etc/d_passwd
Keywords: dialup security password tty sys5
Message-ID: <5041@b11.ingr.com>
Date: 30 Apr 89 02:09:02 GMT
References: <245@chip.UUCP>
Reply-To: linwood@b11.UUCP (Linwood Varney)
Organization: Intergraph Corp. Huntsville, AL
Lines: 50

In article <245@chip.UUCP> mparker@chip.UUCP (M. D. Parker) writes:
>In a system V environment, I'd be interested in knowing how these files
>are used, their formats, etc.

Actually these files are quite useful, especially if you are worried about
security.

The format of the /etc/dialups file is just a list of devices on
separate lines that are concidered dailup ports, for example
"/dev/tty00".  If the port that login is running on is found in dialups
file, then login looks in the /etc/d_passwd file to see if it should ask
for a Dialup Password.  A Dialup Password is asked if the Login Shell
from the password file is found in the d_passwd file, along with a
password.  (I do not remember, but I think if the login shell was not
found, login would use the first entry). 

The format of the d_passwd file is a list of lines with the following format:

Login_Shell:Encrypted_Password:

For example:

$ cat /etc/dialups
/dev/tty00
/dev/tty01
$ cat /etc/d_passwd
/bin/sh:QDilgjTRu/6kU:
/bin/ksh:Kzpmjf5lejk:
/usr/lib/uucp/uucico::
$ 

If you were to login of either port /dev/tty00 or /dev/tty01, and your login
shell was the /bin/sh, it would ask you for a "Dialup Password".  If you
were another computer trying to login as nuucp on one of those ports, a
"Dialup Password" would be skipped. 

Oh, the Encrypted Password is the same as that found in the /etc/passwd file.
There is no easy way to set it.  What I did was password an account, and then
using an editor, copy the password field from passwd to d_passwd.  I also
write a short program to do it.

>...  A string decomposition of my /bin/login
>showed these two files being used not the documentation makes a vailed
>reference to these files.

Documentation is disappointingly vague.  Source also helps..   :-)

	- Linwood Varney			...!uunet!ingr!linwood
	  Network Communications		linwood@ingr.com
	  Intergraph Corporation		Huntsville, Alabama