Re: Ctrl-Alt-Del doesn't work under X?
Hi, > |The way we have handled this at a customer installation is that > |we created a user "shutdown" who was privileded to run shutdown. > > You are not the only one to suggest this... the problem with this is > that it is highly insecure (well, you might say so is C-A-Del from the > keyboard, but this implies access to a card-controlled, monitored > room in our case), people can reboot from all over the net. And our > machines are teaching PCs, i.e. connected to the net. There is no problem with checking for /dev/ttyXX as the controlling tty of he shutdown user's login. Greetings Bernd y -- TO UNSUBSCRIBE FROM THIS MAILING LIST: e-mail the word "unsubscribe" to [EMAIL PROTECTED] . Trouble? e-mail to [EMAIL PROTECTED]
Re: Ctrl-Alt-Del doesn't work under X?
Hello Thomas, Thomas Baetzler scripsit: |The way we have handled this at a customer installation is that |we created a user "shutdown" who was privileded to run shutdown. You are not the only one to suggest this... the problem with this is that it is highly insecure (well, you might say so is C-A-Del from the keyboard, but this implies access to a card-controlled, monitored room in our case), people can reboot from all over the net. And our machines are teaching PCs, i.e. connected to the net. At the moment two solutions look very promising, both the Tcl/Tk script and, IMHO better, Miquel's modified xdm startup. This would mean that, if I can modify the Xlogin keymaps, the kids will find themselves using the familiar combination (very familiar since they use Windoze...). Ciao, Arrigo -- TO UNSUBSCRIBE FROM THIS MAILING LIST: e-mail the word "unsubscribe" to [EMAIL PROTECTED] . Trouble? e-mail to [EMAIL PROTECTED]
Re: SECURE?? [Re: Ctrl-Alt-Del doesn't work under X? ]
On Tue, 08 Oct 1996 16:02:09 CDT Lukas Nellen ([EMAIL PROTECTED] u.unam.mx) wrote: > [EMAIL PROTECTED] said: > > Here comes a small tcl/tk script which will appear under the xdm screen and > > give the opportunity to halt, reboot or go to a console session (ie kill > > xdm). > > As far as I understand TCL/Tk, those script give everybody with access to the > screen immediate root access. As far as I can tell, tkmgr doesn't terminate > when the user logs on. No because tkmgr is killed by the Xstartup_0 script. I'm not sure it's 100% safe, but it should be safe enough... Actually, I don't see breaches in this :-) Phil. -- TO UNSUBSCRIBE FROM THIS MAILING LIST: e-mail the word "unsubscribe" to [EMAIL PROTECTED] . Trouble? e-mail to [EMAIL PROTECTED]
Re: Ctrl-Alt-Del doesn't work under X?
Syrus Nemat-Nasser wrote: > > > From: Arrigo Triulzi <[EMAIL PROTECTED]> > > > Hello, > > > > > > sorry for writing to you direct but this is urgent: it seems > > > that under the Debian X11 installation it is impossible to reboot > > > the machine at the Xlogin prompt under xdm. > Hi. It may not be possible to do this, but here is a way to work > around the problem: > > From the xlogin prompt, you can switch to a virtual console by > C-A-F2 (or C-A-F3, etc.). From a console login prompt, C-A-DEL > works. All you have to do is make sure you have not disallowed > this in your X configuration. The way we have handled this at a customer installation is that we created a user "shutdown" who was privileded to run shutdown. HTH, -- Thomas Baetzler, [EMAIL PROTECTED], [EMAIL PROTECTED] http://home.pages.de/~thb/";>thb's Homepage -- TO UNSUBSCRIBE FROM THIS MAILING LIST: e-mail the word "unsubscribe" to [EMAIL PROTECTED] . Trouble? e-mail to [EMAIL PROTECTED]
SECURE?? [Re: Ctrl-Alt-Del doesn't work under X? ]
[EMAIL PROTECTED] said:
> Here comes a small tcl/tk script which will appear under the xdm screen and
> give the opportunity to halt, reboot or go to a console session (ie kill xdm).
As far as I understand TCL/Tk, those script give everybody with access to the
screen immediate root access. As far as I can tell, tkmgr doesn't terminate
when the user logs on.
If that is indeed the case, the problem is the `send' command of Tk, which
allows any Tk application to send TCL commands to any other on the same screen.
I don't know if recent version of TCL/Tk check for more than the absence of a
xhost list (and therefore enforce xauth authentication). That means a little
script along the lines of
#!/usr/bin/whish
send tkmgr exec {rm -rf /}
can cause quite a bit of inconvenience.
The minimum thing you could do is to disable the send command in Tk using
rename send {}
Then it is your decision if you trust this to be secure or not...
Cheers,
Lukas
---
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Depto. de Fisica Teorica, IFUNAM |
Apdo. Postal 20-364 | Tel.: +52 5 622 5014 ext. 218
01000 Mexico D.F., MEXICO| Fax: +52 5 622 5015
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Re: Ctrl-Alt-Del doesn't work under X?
In article <[EMAIL PROTECTED]>, Syrus Nemat-Nasser <[EMAIL PROTECTED]> wrote: >> From: Arrigo Triulzi <[EMAIL PROTECTED]> >> > Hello, >> > >> >sorry for writing to you direct but this is urgent: it seems >> > that under the Debian X11 installation it is impossible to reboot the >> > machine at the Xlogin prompt under xdm. I know this is a Good Idea >> > (tm) but we are running dual-boot systems and this is a requirement so >> > that students can switch back to DOS when then need. > >Hi. It may not be possible to do this, but here is a way to work >around the problem: > >>From the xlogin prompt, you can switch to a virtual console by C-A-F2 (or >C-A-F3, etc.). From a console login prompt, C-A-DEL works. All you have >to do is make sure you have not disallowed this in your X configuration. If you check /etc/X11/xdm/Xresources, you'll see a couple of keys defined: xlogin*login.translations: #override\ CtrlR: abort-display()\n\ F1: set-session-argument(failsafe) finish-field()\n\ CtrlReturn: set-session-argument(failsafe) finish-field()\n\ Return: set-session-argument() finish-field() As you can see Ctrl-R is abort-display, which kills the xdm server. If you then set up things so that after that xdm terminates a shutdown -r now is executed, you're set. It would also be possible to define Ctrl-Alt-Del for this, ofcourse. Only I don't know what the definition of that would look like, probably something like CtrlMetaDelete: abort-display or so. The easiest way is then to create a script in /usr/local/bin called say lxdm, that looks like this: #! /bin/sh /usr/bin/X11/xdm --nodaemon /sbin/shutdown -r now sleep 10 And then you call this from /etc/inittab in runlevel 5: x5:5:respawn:/usr/local/bin/lxdm Instead of the standard xdm, so turn off the standard xdm first. All this results in Ctrl-R at the xdm prompt rebooting the machine! Mike. -- | Miquel van Smoorenburg \ The answer to Life, the Universe and Everything \ | [EMAIL PROTECTED] \ Just reinstall windows and try again, sir. \ -- TO UNSUBSCRIBE FROM THIS MAILING LIST: e-mail the word "unsubscribe" to [EMAIL PROTECTED] . Trouble? e-mail to [EMAIL PROTECTED]
Re: Ctrl-Alt-Del doesn't work under X?
> >I don't know terribly much about X. Someone else please help this user. > > Thanks > > Bruce > >From: Arrigo Triulzi <[EMAIL PROTECTED]> >> Hello, >> >> sorry for writing to you direct but this is urgent: it seems >> that under the Debian X11 installation it is impossible to reboot the >> machine at the Xlogin prompt under xdm. I know this is a Good Idea >> (tm) but we are running dual-boot systems and this is a requirement so >> that students can switch back to DOS when then need. >> >> Basically, if we can't find a way of doing this we have to >> remove Linux and we lose the chance of introducing it into the Dept. >> >> Please let me know if you have any idea on how to get C-A-Del >> to work at the Xlogin prompt under xdm. I have checked the HOWTO's but >> to no avail. >> >> Thanks, >> >> Arrigo This is what I do at home: At the xdm prompt, press Ctrl-R (^R), this will stop the xdm program and return you to the last virtual terminal you used. Then press Ctrl-Alt-Del. So it's Ctrl-R Ctrl-Alt-Del Hope this helps, Jeroen van der Most -- TO UNSUBSCRIBE FROM THIS MAILING LIST: e-mail the word "unsubscribe" to [EMAIL PROTECTED] . Trouble? e-mail to [EMAIL PROTECTED]
Re: Ctrl-Alt-Del doesn't work under X?
: From: Arrigo Triulzi <[EMAIL PROTECTED]> : > Hello, : > : > sorry for writing to you direct but this is urgent: it seems : > that under the Debian X11 installation it is impossible to reboot the : > machine at the Xlogin prompt under xdm. I know this is a Good Idea : > (tm) but we are running dual-boot systems and this is a requirement so : > that students can switch back to DOS when then need. : > : > Basically, if we can't find a way of doing this we have to : > remove Linux and we lose the chance of introducing it into the Dept. : > : > Please let me know if you have any idea on how to get C-A-Del : > to work at the Xlogin prompt under xdm. I have checked the HOWTO's but : > to no avail. We use the following solution here: 1. Creat a user "shutdown" or "reboot". 2. Give him a password. 3. Change /etc/passwd so that a) his user id is equal to root, b) his home directory is some safe place c) his default shell is /sbin/sysdown 4. sysdown has to be a script that calls shutdown, e.g. #!/bin/sh /sbin/shutdown -h now 5. create a file .xsession.linux in his home directory which calls sysdown. Attention! In this solution, everybody who knows the shutdown-passwd can shutdown the machine even from a remote system. Hope this meets your needs. Best regards -- Volker Volker Ossenkopf, E-mail: [EMAIL PROTECTED] Astrophysikalisches Institut und\\/// Universitaets-Sternwarte Jena ( . . ) Tel.: 03641/630324 --oOo--(_)--oOo- -- TO UNSUBSCRIBE FROM THIS MAILING LIST: e-mail the word "unsubscribe" to [EMAIL PROTECTED] . Trouble? e-mail to [EMAIL PROTECTED]
Re: Ctrl-Alt-Del doesn't work under X?
On Mon, 07 Oct 1996 12:43:00 PDT Bruce Perens ([EMAIL PROTECTED]) wrote: > I don't know terribly much about X. Someone else please help this user. Here it comes... > From: Arrigo Triulzi <[EMAIL PROTECTED]> > > Hello, > > > > sorry for writing to you direct but this is urgent: it seems > > that under the Debian X11 installation it is impossible to reboot the > > machine at the Xlogin prompt under xdm. I know this is a Good Idea > > (tm) but we are running dual-boot systems and this is a requirement so > > that students can switch back to DOS when then need. > > > > Basically, if we can't find a way of doing this we have to > > remove Linux and we lose the chance of introducing it into the Dept. > > > > Please let me know if you have any idea on how to get C-A-Del > > to work at the Xlogin prompt under xdm. I have checked the HOWTO's but > > to no avail. I won't suggest to you to enable CTRL-ALT-DEL. It doesn't work because under X, the server has full control over the keyboard, and the CRTL-ALT-DEL doesn't reach init (which normally does whatever you want, generally a reboot). As we're under X, let's be gooey (GUI). Here comes a small tcl/tk script which will appear under the xdm screen and give the opportunity to halt, reboot or go to a console session (ie kill xdm). I had it installed in /usr/X11R6/lib/X11/xdm/tkmgr, it it sits better in /usr/local/. Also included are the new Xsetup_0 and XStartup_0 scripts to be put in /etc/X11/xdm (they're pretty close to the original). BTW, that means that you want to install the tcl and tk package (any version will do, only the runtime packages are needed). Hope that helps. Phil. PS: I've cc'ed this to the list as I think quite a few people might be interested. scriptwdHCuwREYH.script Description: tkmgr scriptsDnF6vJ1CT.script Description: Xsetup_0 scriptip7XajfnyR.script Description: Xstartup_0
Re: Ctrl-Alt-Del doesn't work under X?
> From: Arrigo Triulzi <[EMAIL PROTECTED]> > > Hello, > > > > sorry for writing to you direct but this is urgent: it seems > > that under the Debian X11 installation it is impossible to reboot the > > machine at the Xlogin prompt under xdm. I know this is a Good Idea > > (tm) but we are running dual-boot systems and this is a requirement so > > that students can switch back to DOS when then need. > > > > Basically, if we can't find a way of doing this we have to > > remove Linux and we lose the chance of introducing it into the Dept. > > > > Please let me know if you have any idea on how to get C-A-Del > > to work at the Xlogin prompt under xdm. I have checked the HOWTO's but > > to no avail. Hi. It may not be possible to do this, but here is a way to work around the problem: >From the xlogin prompt, you can switch to a virtual console by C-A-F2 (or C-A-F3, etc.). From a console login prompt, C-A-DEL works. All you have to do is make sure you have not disallowed this in your X configuration. Syrus. -- Syrus Nemat-Nasser <[EMAIL PROTECTED]>UCSD Physics Dept. -- TO UNSUBSCRIBE FROM THIS MAILING LIST: e-mail the word "unsubscribe" to [EMAIL PROTECTED] . Trouble? e-mail to [EMAIL PROTECTED]
Ctrl-Alt-Del doesn't work under X?
I don't know terribly much about X. Someone else please help this user. Thanks Bruce From: Arrigo Triulzi <[EMAIL PROTECTED]> > Hello, > > sorry for writing to you direct but this is urgent: it seems > that under the Debian X11 installation it is impossible to reboot the > machine at the Xlogin prompt under xdm. I know this is a Good Idea > (tm) but we are running dual-boot systems and this is a requirement so > that students can switch back to DOS when then need. > > Basically, if we can't find a way of doing this we have to > remove Linux and we lose the chance of introducing it into the Dept. > > Please let me know if you have any idea on how to get C-A-Del > to work at the Xlogin prompt under xdm. I have checked the HOWTO's but > to no avail. > > Thanks, > > Arrigo -- Bruce Perens, Pixar Animation Studios *** "Toy Story" video tape in U.S. stores October 30 *** Worldwide box office total for "Toy Story": $353,275,005 -- TO UNSUBSCRIBE FROM THIS MAILING LIST: e-mail the word "unsubscribe" to [EMAIL PROTECTED] . Trouble? e-mail to [EMAIL PROTECTED]
