etc/issue : undocumented, etc/dialups : undocumented etc..

[Ralph-Diether Marzusch]

> 
> Skimming tru my sysV manuals I came across the file /etc/issue, in the
> man pages for getty. However it is only mentioned, no description.
> I remember seeing somewhere it differentiated between several projects,
> and then echoed a specific line when getty started. No reasonable file
> format did the trick however, so I'd like to ask if anyone knows what
> format to use or else what the file is for.

I'm using System V/AT - there it just outputs the contents of /etc/issue
before the 'System name: xxxx' message and the 'login: ' prompt.

> In my bin/login (I'm on a 3B2, V3.1) after an od I found the path:
> /etc/dialups. Now this isn't even in the manuals. Again where is it used
> for, and what is the format. Maybe it's a relic, but there no means for
> me to check that out.

For any terminal listed in /etc/dialups a secondary password will be requested
after the user's password (from /etc/passwd) has been verified.
The password is taken from /etc/d_passwd - see the following example:

/etc/dialups:
  /dev/tty0
  /dev/tty1

/etc/d_passwd:
  /usr/lib/uucp/uucico::	# /usr/lib/uucp/uucico: no dialup password
  /bin/rsh:PASSWORD1HERE:	# /bin/rsh: dialup password
  /bin/sh:PASSWORD2HERE:	# /bin/sh: dialup password
  :PASSWORD3HERE:		# shell not specified (defaults to: /bin/sh)
  /usr/lbin/mailbox::		# your mailbox program: no dialup pwd required
  /bin/sh:*:			# anything else: can't login

/etc/passwd:
  ...
  a:PASSWORD HERE:73:100:User A:/usr/users/a:/bin/rsh
  b:PASSWORD HERE:74:100:User B:/usr/users/b:/bin/sh
  c:PASSWORD HERE:75:100:User C:/usr/users/c:
  d:PASSWORD HERE:76:100:User D:/usr/users/d:/usr/lbin/mailbox
  e:PASSWORD HERE:77:100:User E:/usr/users/e:/usr/lbin/mailbox_manager

User A must enter dialup password #1, user B must enter dialup password
#2 and user C must enter dialup password #3. User D will not be requested to
enter a dialup password. User E will be asked for a dialup password, but there
is no password that matches '*' when encrypted, so E can't login on tty0 and
tty1.

Please note: the *last* entry for /bin/sh is the default entry for *any* shell
not mentioned in this list. The *first* entry for /bin/sh will be applied to
/bin/sh itself. If there is only one entry for /bin/sh it is used for /bin/sh
and for every shell not mentioned in this list.
The entries for /bin/sh and for '' (empty shell field in /bin/passwd) are
considered different.
The password must be encrypted the same way the passwords in /etc/passwd are
encrypted (see crypt(3) ).

Pretty complicated, isn't it? Have a look at the source of /bin/login, it's
worse. But it's a nice (undocumented :-( ) feature.

Ralph-Diether Marzusch
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