364 lines
5.1 KiB
HTML
364 lines
5.1 KiB
HTML
<HTML
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><HEAD
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><TITLE
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>Adjust behaviour of CtrlAltDelete</TITLE
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><META
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NAME="GENERATOR"
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CONTENT="Modular DocBook HTML Stylesheet Version 1.7"><LINK
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REL="HOME"
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TITLE="Remote Serial Console HOWTO"
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HREF="index.html"><LINK
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REL="UP"
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TITLE="Security"
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HREF="security.html"><LINK
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REL="PREVIOUS"
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TITLE="Magic SysRq key"
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HREF="security-sysrq.html"><LINK
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REL="NEXT"
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TITLE="Log attempted access"
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HREF="security-log.html"></HEAD
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><BODY
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CLASS="SECTION"
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BGCOLOR="#FFFFFF"
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TEXT="#000000"
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LINK="#0000FF"
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VLINK="#840084"
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ALINK="#0000FF"
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><DIV
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CLASS="NAVHEADER"
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><TABLE
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SUMMARY="Header navigation table"
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WIDTH="100%"
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BORDER="0"
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CELLPADDING="0"
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CELLSPACING="0"
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><TR
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><TH
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COLSPAN="3"
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ALIGN="center"
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>Remote Serial Console HOWTO</TH
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></TR
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><TR
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><TD
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WIDTH="10%"
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ALIGN="left"
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VALIGN="bottom"
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><A
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HREF="security-sysrq.html"
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ACCESSKEY="P"
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>Prev</A
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></TD
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><TD
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WIDTH="80%"
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ALIGN="center"
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VALIGN="bottom"
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>Chapter 9. Security</TD
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><TD
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WIDTH="10%"
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ALIGN="right"
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VALIGN="bottom"
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><A
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HREF="security-log.html"
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ACCESSKEY="N"
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>Next</A
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></TD
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></TR
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></TABLE
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><HR
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ALIGN="LEFT"
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WIDTH="100%"></DIV
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><DIV
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CLASS="SECTION"
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><H1
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CLASS="SECTION"
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><A
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NAME="SECURITY-CTRLALTDEL"
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></A
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>9.10. Adjust behaviour of <B
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CLASS="KEYCAP"
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>Ctrl</B
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>-<B
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CLASS="KEYCAP"
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>Alt</B
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>-<B
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CLASS="KEYCAP"
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>Delete</B
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></H1
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><P
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>The <SPAN
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CLASS="PRODUCTNAME"
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>IBM PC</SPAN
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> used <B
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CLASS="KEYCAP"
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>Ctrl</B
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>-<B
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CLASS="KEYCAP"
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>Alt</B
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>-<B
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CLASS="KEYCAP"
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>Delete</B
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> to launch a reboot of the computer. Linux traps this
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key chord and makes it available to the
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<SPAN
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CLASS="APPLICATION"
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>init</SPAN
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> system. This is done by sending
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the <SPAN
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CLASS="APPLICATION"
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>init</SPAN
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> process a
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<TT
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CLASS="LITERAL"
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>SIGINT</TT
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> signal (although <B
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CLASS="COMMAND"
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>ctrlaltdel
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hard</B
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> can undo this trap and make the key chord reboot the
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comptuer immediately). The <SPAN
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CLASS="APPLICATION"
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>init</SPAN
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> system
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uses <TT
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CLASS="FILENAME"
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>/etc/inittab</TT
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> to determine how to handle
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the signal generated by the <B
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CLASS="KEYCAP"
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>Ctrl</B
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>-<B
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CLASS="KEYCAP"
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>Alt</B
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>-<B
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CLASS="KEYCAP"
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>Delete</B
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> key
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chord.</P
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><P
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>Most distributions cleanly reboot the system, mimicing the
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behaviour that most users expect. <A
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HREF="security-ctrlaltdel.html#SECURITY-CTRLALTDEL-TELINIT-DEFAULT"
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>Figure 9-14</A
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> shows how this is
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done.</P
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><DIV
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CLASS="FIGURE"
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><A
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NAME="SECURITY-CTRLALTDEL-TELINIT-DEFAULT"
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></A
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><P
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><B
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>Figure 9-14. Default handling of <B
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CLASS="KEYCAP"
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>Ctrl</B
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>-<B
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CLASS="KEYCAP"
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>Alt</B
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>-<B
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CLASS="KEYCAP"
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>Delete</B
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> in
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<TT
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CLASS="FILENAME"
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>/etc/inittab</TT
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></B
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></P
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><TABLE
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BORDER="0"
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BGCOLOR="#E0E0E0"
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WIDTH="100%"
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><TR
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><TD
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><FONT
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COLOR="#000000"
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><PRE
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CLASS="PROGRAMLISTING"
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># Trap CTRL-ALT-DELETE
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ca::ctrlaltdel:/sbin/shutdown -t3 -r now</PRE
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></FONT
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></TD
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></TR
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></TABLE
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></DIV
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><P
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>Depending upon each individual site you may wish to disable
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<B
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CLASS="KEYCAP"
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>Ctrl</B
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>-<B
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CLASS="KEYCAP"
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>Alt</B
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>-<B
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CLASS="KEYCAP"
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>Delete</B
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>. This is shown in <A
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HREF="security-ctrlaltdel.html#SECURITY-CTRLALTDEL-TELINIT-IGNORE"
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>Figure 9-15</A
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>.</P
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><DIV
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CLASS="FIGURE"
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><A
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NAME="SECURITY-CTRLALTDEL-TELINIT-IGNORE"
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></A
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><P
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><B
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>Figure 9-15. Ignoring <B
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CLASS="KEYCAP"
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>Ctrl</B
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>-<B
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CLASS="KEYCAP"
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>Alt</B
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>-<B
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CLASS="KEYCAP"
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>Delete</B
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> in
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<TT
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CLASS="FILENAME"
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>/etc/inittab</TT
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></B
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></P
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><TABLE
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BORDER="0"
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BGCOLOR="#E0E0E0"
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WIDTH="100%"
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><TR
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><TD
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><FONT
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COLOR="#000000"
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><PRE
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CLASS="PROGRAMLISTING"
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># Trap CTRL-ALT-DELETE and do nothing
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ca::ctrlaltdel:</PRE
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></FONT
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></TD
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></TR
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></TABLE
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></DIV
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><P
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>Alternatively, you may wish to cleanly shut down the
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computer. This is very easy to explain to operators and
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instructions can be displayed on the monitor using
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<TT
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CLASS="FILENAME"
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>/etc/issue</TT
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> or a <SPAN
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CLASS="PRODUCTNAME"
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>Post-it
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Note</SPAN
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>. If the computer uses <SPAN
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CLASS="PRODUCTNAME"
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>Advanced
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Power Management</SPAN
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> (or <SPAN
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CLASS="ACRONYM"
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>APM</SPAN
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>) then
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shutting down the computer will also remove the power.</P
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><DIV
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CLASS="FIGURE"
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><A
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NAME="SECURITY-CTRLALTDEL-TELINIT-HALT"
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></A
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><P
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><B
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>Figure 9-16. Shut down cleanly upon <B
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CLASS="KEYCAP"
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>Ctrl</B
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>-<B
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CLASS="KEYCAP"
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>Alt</B
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>-<B
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CLASS="KEYCAP"
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>Delete</B
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> in
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<TT
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CLASS="FILENAME"
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>/etc/inittab</TT
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></B
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></P
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><TABLE
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BORDER="0"
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BGCOLOR="#E0E0E0"
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WIDTH="100%"
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><TR
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><TD
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><FONT
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COLOR="#000000"
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><PRE
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CLASS="PROGRAMLISTING"
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># Trap CTRL-ALT-DELETE and shut down
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ca::ctrlaltdel:/sbin/shutdown -t3 -h now</PRE
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></FONT
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></TD
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></TR
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></TABLE
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></DIV
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></DIV
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><DIV
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CLASS="NAVFOOTER"
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><HR
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ALIGN="LEFT"
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WIDTH="100%"><TABLE
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SUMMARY="Footer navigation table"
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WIDTH="100%"
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BORDER="0"
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CELLPADDING="0"
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CELLSPACING="0"
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><TR
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><TD
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WIDTH="33%"
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ALIGN="left"
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VALIGN="top"
|
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><A
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HREF="security-sysrq.html"
|
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ACCESSKEY="P"
|
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>Prev</A
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></TD
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><TD
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WIDTH="34%"
|
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ALIGN="center"
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VALIGN="top"
|
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><A
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|
HREF="index.html"
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ACCESSKEY="H"
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>Home</A
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></TD
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><TD
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WIDTH="33%"
|
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ALIGN="right"
|
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VALIGN="top"
|
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><A
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|
HREF="security-log.html"
|
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ACCESSKEY="N"
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>Next</A
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></TD
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></TR
|
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><TR
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><TD
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WIDTH="33%"
|
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ALIGN="left"
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VALIGN="top"
|
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>Magic <B
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CLASS="KEYCAP"
|
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>SysRq</B
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> key</TD
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><TD
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WIDTH="34%"
|
|
ALIGN="center"
|
|
VALIGN="top"
|
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><A
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HREF="security.html"
|
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ACCESSKEY="U"
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>Up</A
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></TD
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><TD
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WIDTH="33%"
|
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ALIGN="right"
|
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VALIGN="top"
|
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>Log attempted access</TD
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></TR
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></TABLE
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></DIV
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></BODY
|
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></HTML
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> |