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284 lines
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<TITLE>LINUX PLIP MINI-HOWTO: FAQ.</TITLE>
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<A HREF="PLIP.html#toc7">Contents</A>
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<HR>
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<H2><A NAME="s7">7. FAQ.</A></H2>
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<P>This section will (hopefully) solve your problems. If you have any other
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question, feel free to mail me anytime.
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<P>
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<UL>
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<LI>I get these messages at boot time (or when I load the plip module):
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<BLOCKQUOTE><CODE>
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<PRE>
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SIOCSIFADDR: No such device
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SIOCADDRT: Network is unreachable
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</PRE>
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</CODE></BLOCKQUOTE>
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and when I try to set up the link as written above, I get again error
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messages like:
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<BLOCKQUOTE><CODE>
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<PRE>
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SIOCSIFADDR: No such device
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SIOCSIFDSTADDR: No such device
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SIOCADDRT: Network is unreachable
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mount clntudp_create: RPC: Port Mapper failure - RPC: Unable to send
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</PRE>
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</CODE></BLOCKQUOTE>
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<UL>
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<LI>The kernel, for some reason, hasn't PLIP support enabled. This could be
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due to:
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<UL>
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<LI>You didn't answer yes to "PLIP support? " during kernel configuration.</LI>
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<LI>You answered yes to "Printer support? " during kernel configuration.</LI>
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<LI>You compiled PLIP as a module, so you must load it. </LI>
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<LI>You are addressing the wrong port, i.e. you wrote for instance plip1
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instead of plip0.</LI>
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</UL>
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</LI>
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</UL>
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</LI>
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<LI>Is there a way to support both PLIP and LP, beside modules, perhaps with
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two parallel ports?
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<UL>
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<LI>Yes, so far there are two ways, described in the "Patches to make PLIP
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and LP live together":
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<UL>
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<LI>You can apply a patch to make the kernel support both.</LI>
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<LI>You can apply another patch to make the kernel use a parallel port
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for PLIP and another for LP. </LI>
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</UL>
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</LI>
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</UL>
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</LI>
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<LI>I have created the script that connects my 2 computers. I set up the
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link automatically in my rc.inet2, where I call a script that creates
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the link and enables NFS.
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My "two" hosts mounts some "one"'s directories; I have added the
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correct entries in "two"'s /etc/fstab.
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If I boot "two" when "one" is down, "two" halts for some minutes
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on the "mounting remote file systems...".
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<UL>
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<LI>This happens because "two" waits to mount the "one" filesystems, but
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if "one" is down you must wait until "two" is bored of waiting.
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To avoid this, you may:
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<UL>
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<LI>Comment out in rc.inet2 the command that mounts the remote filesystems</LI>
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<LI>Remove the entry in "two"'s /etc/fstab and mount the remote filesystems
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manually when and if you need.</LI>
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<LI>A better solution would be for "two" to detect upon booting whether
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"one" is up, and mount the filesystem if it is. This can be
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accomplished by replacing the mount command in rc.d or whereever
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with something like the following:
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<HR>
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<PRE>
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if ping -c 5 one ; then
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mount one:/.....
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fi
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</PRE>
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<HR>
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</LI>
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</UL>
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</LI>
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</UL>
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</LI>
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<LI>My link is up, but ping fails. I receive the following message from the
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kernel:
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<BLOCKQUOTE><CODE>
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<PRE>
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plip1: timed out (1, 89)
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</PRE>
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</CODE></BLOCKQUOTE>
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or similar messages.
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<UL>
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<LI>This means that the "your side of the link" is working, your machine
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sends the signal, but the "other side" isn't answering or your side is
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not waiting at the proper IRQ/IO Address.
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This is the most common problem and, alas, has a lot of possible reasons,
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usually bad cable or wrong IRQ and/or IO Address. The wrong IRQ is the
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source of over 60% of the problems, so it's very likely that changing it
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will remove the problem.
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Here is a detailed list of possible reasons:
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<UL>
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<LI>The cable isn't plugged properly or is broken or is wrong. Check it, if
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possible, between two Linux hosts which already work with PLIP. If it
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is not possible, then at least test the cable with a tester. The fact
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that the cable worked/not worked with DOS/win95 is a good/bad omen
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but is not a proof.</LI>
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<LI>The "other side" machine has not PLIP up.</LI>
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<LI>You are linked with a notebook with a not proper parallel port, see
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below.</LI>
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<LI>You have a really cheap parallel port that is a simple "printer" port,
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so can send and not receive.</LI>
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<LI>Your parallel port is not set as (at least) bi-directional. Do it in
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the BIOS configuration. Advanced parallel port settings like EPP or
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ECP are ok. </LI>
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<LI>The parallel ports have different irq, so you have to load the plip
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module (or the lp module) with a different irq. Go back to the chapter
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"Activate the PLIP link" and choose a different irq.</LI>
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<LI>Some other device may have shared your irq (which usually is irq 7),
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it may be a sound card. Do not trust DOS programs like MSD, instead
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try to load the plip module with a different irq.</LI>
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</UL>
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</LI>
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</UL>
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</LI>
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<LI>I put the right IRQ and IO Address, but it still doesn't work. I got the
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addresses from the MSD command.
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<UL>
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<LI>I got a report from MSD giving wrong port addresses. Try to use this
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program: http://www.cs.caltech.edu/ huny/para13.zip.</LI>
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</UL>
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</LI>
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<LI>My link is up, and ping works. I sometimes receive the following message
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from the kernel:
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<BLOCKQUOTE><CODE>
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<PRE>
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plip1: timed out (1, 89)
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</PRE>
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</CODE></BLOCKQUOTE>
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or similar messages.
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<UL>
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<LI> This means that the other side has not answered before the timeout.
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If all is working, you can ignore these messages: usually means that the
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other side is much slower than yours, either due to older hardware or more
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load. You can try to tune PLIP with the plipconfig command.</LI>
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</UL>
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</LI>
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<LI>I have installed the PLIP connection but if I ping I get 100% data loss.
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I connected my desktop with a notebook.
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<UL>
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<LI>Some notebook's parallel ports aren't good for PLIP, because they are
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only "printer ports", i.e. they can only transmit but not receive the
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data. So far I don't know if there is a way to make them work.
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The only hope is:
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<UL>
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<LI>Look at your notebook setup, perhaps there is a way to configure
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the parallel port as a parallel port instead of a printer port. Usually
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is called "parallel enhanced mode".</LI>
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<LI>Try plip mode 0. Alas I don't know how to do it and/or if it works
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or is still available in the last kernels.</LI>
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</UL>
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</LI>
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</UL>
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</LI>
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<LI>What speeds can I achieve with PLIP?
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<UL>
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<LI>This is an hard question to answer to, because there are MANY factors
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that can change deeply your performance:
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<UL>
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<LI>The CPU speed on both the sides of the link.</LI>
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<LI>The parallel port type and settings.</LI>
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<LI>The system load.</LI>
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<LI>What do you use PLIP for.</LI>
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</UL>
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Just to give a rough idea, you should achieve about 40Kbytes/sec, much
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faster than any serial rate and near to a low-level ethernet card.</LI>
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</UL>
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</LI>
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<LI>What happens if I need to ifconfig up and ifconfig down many times plip1?
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<UL>
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<LI>Seems that you need to add a -arp to the ifconfig command, except for
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the first time after each boot. I don't need, but perhaps someone does.</LI>
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</UL>
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</LI>
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<LI>I have read the IP numbers reserved for private networks and your
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200.0.0.1 and 200.0.0.2 are not in these ranges. Shouldn't they be changed?
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<UL>
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<LI>Yes, they should. But as I underline since the beginning I choose these
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IP addresses only because of their simplicity, you are free to change
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them as you wish. Here is a cut from the net-2-howto:
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<BLOCKQUOTE><CODE>
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<PRE>
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RFC1597 has specifically reserved some IP addresses for private
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networks. You should use these as they prevent anything nasty
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happening if you accidentally get connected to the Internet. The
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addresses reserved are:
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10.0.0.0 - 10.255.255.255
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172.16.0.0 - 172.31.255.255
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192.168.0.0 - 192.168.255.255
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</PRE>
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</CODE></BLOCKQUOTE>
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</LI>
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</UL>
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</LI>
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<LI>Is there a way to fine tune PLIP parameters without editing the source
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code?
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<UL>
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<LI>Yes, there is. Try the /sbin/plipconfig command. See the man page for
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more info.</LI>
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</UL>
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</LI>
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<LI>I'm running Debian GNU/Linux, and under Debian, the files
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/etc/rc.d/rc.inet1 and 2 do not exist. Where must I write the plip
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configuration commands?
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<UL>
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<LI>In Debian GNU/Linux you must edit /etc/init.d/network, where you have to
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put all the commands that should stay in rc.inet1 and 2.</LI>
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</UL>
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</LI>
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<LI>I have some problems linking two hosts with PLIP. The first has the
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latest kernel, the second still uses the 1.0.x PLIP version: is this a problem?
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<UL>
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<LI>Yes, it's much better, where is possible, to have the same PLIP
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version on both ends. In the plip.c is written that the actual PLIP cannot
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work with the 1.0.xx PLIP.</LI>
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</UL>
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</LI>
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<LI>Right now PLIP works with 4 bits, what about the 8 bit PLIP I've read
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in the kernel docs? I think is called Mode 1.
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<UL>
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<LI>This Mini-HowTo is for configuration, for technical informations please
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read the /usr/src/linux/drivers/net/README*.PLIP files or contact the
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author. What I know is only this: the standard PLIP uses "null printer"
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cables and is the Mode 0 (don't confuse it with plip0, which is the
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interface name), which uses 4 bits; Mode 1 uses 8 bits and should be
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available already, but will need an handmade cable and will work only
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between 2 Linux hosts. I don't know, once you got the cable, how to set up
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the Mode 1 PLIP link; if somebody does, please let me know.</LI>
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</UL>
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</LI>
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</UL>
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<P>
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<HR>
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