Re: XDM Insecurity revisited

From: Martin K. Petersen (mkpat_private)
Date: Thu Aug 19 1999 - 02:33:18 PDT

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    >>>>> "Jochen" == Jochen Bauer <jtbat_private-STUTTGART.DE> writes:
    
    Jochen> However, this warning seemed to have little effect as (at
    Jochen> least) Digital Unix 4.0E, SuSE Linux 6.1 and Red Hat Linux 6.0
    Jochen> are still (1.5 years later) shipped with this default Xaccess
    Jochen> file.
    
    Same story for Solaris, HP/UX and (iirc) Irix...
    
    
    Jochen> It is somehow ironic that e.g. SuSE now uses tcpwrappers by
    Jochen> default on most TCP services in it's distribution and
    Jochen> describes the use of tcpwrappers in the manual in a special
    Jochen> chapter about security, but fails to close (or even mention)
    Jochen> that way to circumvent login restrictions.
    
    Incidentally, the Gnome Display Manager which is also included in Red
    Hat 6.0 uses tcpwrappers for access control (Unfortunately it is
    slightly broken wrt. XDMCP in the shipped version -- mea culpa).  GDM
    also has an option to disallow root logins and makes extensive use of
    PAM for authentication.
    
    In general, I'd advise anyone running XDM or derivatives (like dtlogin
    from CDE) to block UDP port 177 on their firewall. It's an extremely
    good idea. Believe me...
    
    --
    Martin Kasper Petersen		BOFH, IC1&2, Aalborg University, DK
    



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