415 lines
6.0 KiB
HTML
415 lines
6.0 KiB
HTML
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<HTML
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><HEAD
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><TITLE
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>Configure OpenSSH to use TCP-Wrappers/inetd super server</TITLE
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><META
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NAME="GENERATOR"
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CONTENT="Modular DocBook HTML Stylesheet Version 1.60"><LINK
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REL="HOME"
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TITLE="Securing and Optimizing Linux"
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HREF="index.html"><LINK
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REL="UP"
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TITLE="Software -Securities"
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HREF="soft-netsecured.html"><LINK
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REL="PREVIOUS"
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TITLE="Configure the /etc/ssh/sshd_config file"
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HREF="chap15sec122.html"><LINK
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REL="NEXT"
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TITLE="OpenSSH Per-User Configuration"
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HREF="chap15sec124.html"></HEAD
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CLASS="section"
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BGCOLOR="#FFFFFF"
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><DIV
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><TABLE
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><TR
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><TH
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COLSPAN="3"
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>Securing and Optimizing Linux: RedHat Edition -A Hands on Guide</TH
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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="chap15sec122.html"
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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 15. Software -Securities</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="chap15sec124.html"
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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="AEN8326"
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>15.5. Configure OpenSSH to use TCP-Wrappers/inetd super server</A
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></H1
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><P
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> Tcp-Wrappers should be enabled to start and stop our OpenSSH server. Upon execution, inetd reads its configuration information from a configuration file which, by default, is <TT
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CLASS="filename"
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>/etc/inetd.conf</TT
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>. There must
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be an entry for each field of the configuration file, with entries for each field separated by a tab or a space.
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</P
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><DIV
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CLASS="procedure"
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><OL
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TYPE="1"
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><LI
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><P
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>
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Edit the <TT
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CLASS="filename"
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>inetd.conf</TT
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> file <B
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CLASS="command"
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>vi</B
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> <TT
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CLASS="filename"
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>/etc/inetd.conf</TT
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> and add the line:
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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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><PRE
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CLASS="programlisting"
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> ssh stream tcp nowait root /usr/sbin/tcpd sshd -i
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</PRE
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></TD
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></TR
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></TABLE
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>
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<DIV
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CLASS="important"
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><BLOCKQUOTE
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CLASS="important"
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><P
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><B
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><SPAN
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CLASS="inlinemediaobject"
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><IMG
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SRC="./images/Important.gif"
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ALT="Important"
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></IMG
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></SPAN
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>: </B
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>
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The -i parameter is important since it's specifies that sshd is being run from inetd. Also, update your <TT
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CLASS="filename"
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>inetd.conf</TT
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> file by sending a <B
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CLASS="command"
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>SIGHUP</B
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> signal <B
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CLASS="command"
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>killall</B
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><TT
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CLASS="userinput"
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><B
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>-HUP inetd</B
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></TT
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> after
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adding the above line to the file.
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</P
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></BLOCKQUOTE
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></DIV
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>
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To update your <TT
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CLASS="filename"
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>inetd.conf file</TT
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>, use the following command:
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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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><PRE
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CLASS="screen"
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> [root@deep] /#<B
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CLASS="command"
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>killall</B
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> -HUP inetd
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</PRE
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></TD
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></TR
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></TABLE
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>
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</P
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></LI
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><LI
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><P
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>
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Edit the <TT
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CLASS="filename"
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>hosts.allow</TT
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> file, <B
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CLASS="command"
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>vi</B
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> <TT
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CLASS="filename"
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>/etc/hosts.allow</TT
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> and add the line:
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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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><PRE
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CLASS="programlisting"
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> sshd: 192.168.1.4 win.openna.com
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</PRE
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></TD
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></TR
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></TABLE
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>
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Which mean client <SPAN
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CLASS="acronym"
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>IP</SPAN
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> <TT
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CLASS="literal"
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>192.168.1.4</TT
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> with host name <TT
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CLASS="literal"
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>win.openna.com</TT
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> is allowed to ssh in to the server.
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</P
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></LI
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></OL
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></DIV
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><P
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> These daemon strings for tcp-wrappers are in use by sshd:
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<P
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></P
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><DIV
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CLASS="variablelist"
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><DL
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><DT
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>sshdfwd-X11</DT
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><DD
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><P
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> if you want to allow/deny X11-forwarding
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</P
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></DD
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><DT
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>sshdfwd-<port-number></DT
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><DD
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><P
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>for tcp-forwarding</P
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></DD
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><DT
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>sshdfwd-<port-name></DT
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><DD
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><P
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>port-name defined in <TT
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CLASS="filename"
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>/etc/services</TT
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>. Used in tcp-forwarding</P
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></DD
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></DL
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></DIV
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>
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</P
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><DIV
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CLASS="tip"
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><BLOCKQUOTE
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CLASS="tip"
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><P
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><B
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><SPAN
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CLASS="inlinemediaobject"
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><IMG
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SRC="./images/Tip.gif"
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ALT="Tip"
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></IMG
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></SPAN
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>: </B
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>
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If you do decide to switch to using ssh, make sure you install and use it on all your servers. Having ten secure servers and one insecure is a waste of time.
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</P
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></BLOCKQUOTE
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></DIV
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><P
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> For more details, there are several man pages you can read:
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<P
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></P
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><DIV
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CLASS="variablelist"
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><DL
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><DT
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><SPAN
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CLASS="citerefentry"
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><SPAN
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CLASS="refentrytitle"
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>ssh</SPAN
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>(1)</SPAN
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></DT
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><DD
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><P
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>OpenSSH secure shell client <EM
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>remote login program</EM
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></P
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></DD
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><DT
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><SPAN
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CLASS="citerefentry"
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><SPAN
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CLASS="refentrytitle"
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>ssh [slogin]</SPAN
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>(1)</SPAN
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></DT
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><DD
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><P
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>OpenSSH secure shell client <EM
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>remote login program</EM
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></P
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></DD
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><DT
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><SPAN
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CLASS="citerefentry"
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><SPAN
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CLASS="refentrytitle"
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>ssh-add</SPAN
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>(1)</SPAN
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></DT
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><DD
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><P
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>adds identities for the authentication agent</P
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></DD
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><DT
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><SPAN
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CLASS="citerefentry"
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><SPAN
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CLASS="refentrytitle"
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>ssh-agent</SPAN
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>(1)</SPAN
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></DT
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><DD
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><P
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>authentication agent</P
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></DD
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><DT
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><SPAN
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CLASS="citerefentry"
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><SPAN
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CLASS="refentrytitle"
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>ssh-keygen</SPAN
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>(1)</SPAN
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></DT
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><DD
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><P
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>authentication key generation</P
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></DD
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><DT
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><SPAN
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CLASS="citerefentry"
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><SPAN
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CLASS="refentrytitle"
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>sshd</SPAN
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>(8)</SPAN
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></DT
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><DD
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><P
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>secure shell daemon</P
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></DD
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></DL
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></DIV
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>
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</P
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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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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="chap15sec122.html"
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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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>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="chap15sec124.html"
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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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>Configure the <TT
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CLASS="filename"
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>/etc/ssh/sshd_config file</TT
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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="soft-netsecured.html"
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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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>OpenSSH Per-User Configuration</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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>
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