annoucement: auto-login patch for xdm

[Oswald Buddenhagen <ob6@inf.tu-dresden.de>]

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hi all,

due to a relatively popular demand on such a (mis-)feature at debian-user,
i became interested in automatic login, too. so i just implemented it
for xdm, kdm and wdm (wdm not tested). i thought about gdm, too, but it
seems not to be directly based on xdm, so it would be much work.

the home page of the patches (precompiled executables are also
available) is at http://www.inf.tu-dresden.de/~ob6/unix/xautolog.html
(copy attached for off-line reading).

any constructive feedback is welcome.

sorry, if this is not the right place to announce this, :-(
but as the idea was brought to me at debian-user ... :-)

have fun!


ps: are there already other implementations of x-based auto-login? ;-/

pps: please cc me, as i unsubscribed from the lists due to a lack of
time. well, at least on debian-user cc-ing is the normal procedure anyway
... :)

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Title: Auto-login patch for XDM

Short description

You hate it to have to log into your own PC all the time? Then this patch is for you! It lets you configure a user for whom a X session should be started automatically when the system boots. When the server crashes (or is terminated by alt-ctrl-backspace), the user is logged in again. If you "cleanly" log off the user, then the normal login screen will show up.

Security concerns

I already can hear all the complaints from the paranoid security-gurus ... *g*
So here is my statement:
Don't use it if your machine can be physically accessed by untrusted persons. This is even more a concern, if you specify auto-login for remote X-displays (which log in via XDMCP).
As this auto-login affects only logins on X-displays, it is perfectly save to have all the usual server daemons (e.g., telnet, ftp, etc.) installed - all of them will need normal password authentication.
NEVER let root to be automatically logged in - by doing this you would reach the security level of WinDOS (i.e. no local security at all) - but you already know that. ;-)

Download & Install

Get the XDM patch for XFree 3.3.6 or the KDM patch for KDE 1.1.2. The XDM patch is applied by changing into the "programs" subdirectory of the XFree source tree and running "patch -p0 < xdm.patch"; it will take forever to build the whole xfree (but you probably do not have to do so). The KDM patch is applied by running "patch -p0 < kdm.patch" in the kdebase source directory; compiling the whole kdebase will take a while, too.
You can also download precompiled executables for i386 Debian Potato (they _may_ run on other glibc2.1 Linux-distributions as well): XDM or KDM. Put it in /usr/local/bin and chenge the DAEMON path in the init script (/etc/init.d/xdm on Potato).
There is also a XDM 3.3.2 patch, which is supposed to be used with WDM (v1.19), but it is untested!.

Configuration

The auto-login extension is configured by adding resource specifications to the normal xdm-config (/etc/X11/xdm/xdm-config resp. /etc/X11/kdm/kdm-config on Debian; /usr/X11R6/lib/X11/xdm/xdm-config on many other *nix/Linux systems).

• autoUser is the user to be logged in automatically (mandatory).
• autoString are the parameters for the Xsession (optional).
• autoPass is the password of the user to be logged in. This is needed only if you use Kerberos5 authentication or NIS. As the password must be stored in clear text, you have to "chmod 600" your xdm-config to prevent everybody with an account from reading it. This is mostly untested!

Examples:

1. Automatically log in a user on the local console:
   

   DisplayManager._0.autoUser:     ossi
   DisplayManager._0.autoString:   kde
   

2. Automatically log in a user on the remote display remmach.domain.com:0:
   

   DisplayManager.remmach_domain_com_0.autoUser:     remoti
   DisplayManager.remmach_domain_com_0.autoString:   wmaker
   

3. Automatically log in a user on the second display of the local machine; supply a password:
   

   DisplayManager._1.autoUser:     loki2
   DisplayManager._1.autoPass:     secret