251 lines
4.0 KiB
HTML
251 lines
4.0 KiB
HTML
<HTML
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><HEAD
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><TITLE
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>Pitfalls</TITLE
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><META
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NAME="GENERATOR"
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CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+
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"><LINK
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REL="HOME"
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TITLE="VPN HOWTO"
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HREF="index.html"><LINK
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REL="UP"
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TITLE="Addenda"
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HREF="c671.html"><LINK
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TITLE="Addenda"
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HREF="c671.html"><LINK
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REL="NEXT"
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TITLE="Hardware and Software Requirements"
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HREF="x700.html"></HEAD
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><BODY
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CLASS="sect1"
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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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>VPN 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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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 6. Addenda</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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><HR
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ALIGN="LEFT"
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WIDTH="100%"></DIV
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><DIV
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CLASS="sect1"
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><H1
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CLASS="sect1"
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><A
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NAME="pitfalls">6.1. Pitfalls</H1
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><P
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> Here are just a few of the snags that I've run into while using this
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system. I put them here so that you can hopefully avoid them. If you
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run into any new ones, please <A
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HREF="mailto:matthew@shinythings.com"
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TARGET="_top"
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> email them to me</A
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> so that I can keep track, and help others avoid
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them.</P
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><DIV
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CLASS="sect2"
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><H2
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CLASS="sect2"
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><A
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NAME="AEN677">6.1.1. read: I/O error</H2
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><P
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> This error is associated with mis-matched
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versions off pppd. If you get it, try upgrading both ends of the
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connection to the latest version of pppd. I've found that pppd version
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2.2 has this problem, so use version 2.3.7 or 2.3.8 instead.
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</P
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></DIV
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><DIV
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CLASS="sect2"
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><H2
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CLASS="sect2"
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><A
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NAME="AEN680">6.1.2. SIOCADDRT: Network is unreachable</H2
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><P
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> This error is generated by <B
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CLASS="command"
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>route</B
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>. I've seen it happen when the
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sleep time between <B
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CLASS="command"
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>ssh</B
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> and <B
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CLASS="command"
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>ppd</B
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> is not long enough. If
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you get this error, run <B
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CLASS="command"
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>ifconfig</B
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>, and you may see that there is no
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pppX interface. This means that <B
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CLASS="command"
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>ssh</B
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> was not done
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authenticating before <B
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CLASS="command"
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>pppd</B
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> was launched, and therefore
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<B
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CLASS="command"
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>pppd</B
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> did not make the connection. just increase the delay, and
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your problems will be solved.
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</P
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><P
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> I wonder however if there might be some pppd option that will fix this
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problem.
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</P
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></DIV
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><DIV
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CLASS="sect2"
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><H2
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CLASS="sect2"
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><A
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NAME="ipv4forwarding">6.1.3. IPv4 Forwarding and 2.2 kernels</H2
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><P
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> In the new 2.2 kernel, you must specifically enable IP forwarding in the
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kernel at boot up. This with the following command:
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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="screen"
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> # echo 1 > /proc/sys/net/ipv4/ip_forward
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</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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><P
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> Without this, the kernel will not forward any packets, and hence the
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server will not work, nor will any of the gatewaying clients.
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</P
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></DIV
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><DIV
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CLASS="sect2"
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><H2
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CLASS="sect2"
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><A
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NAME="AEN696">6.1.4. Routing</H2
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><P
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> It should go without saying, but be careful when you are routing real numbers
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that you don't route traffic destined for the VPN server's external address
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through the tunnel. It won't make it. (yes, this <EM
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>is</EM
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> from personal
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experience.)
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</P
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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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><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="c671.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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HREF="index.html"
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>Home</A
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></TD
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VALIGN="top"
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HREF="x700.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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>Addenda</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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HREF="c671.html"
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>Up</A
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WIDTH="33%"
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ALIGN="right"
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VALIGN="top"
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>Hardware and Software Requirements</TD
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></TR
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> |