Remove entry for games through PPP NAT. This has not been true for some time.
Sponsored by: iXsystems
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svn2git
2020-12-08 03:00:23 +00:00
svn path=/head/; revision=44835
1 changed files with 0 additions and 86 deletions
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@ -6424,92 +6424,6 @@ ATDT1234567</programlisting>
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</answer>
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</qandaentry>
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<qandaentry>
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<question xml:id="ppp-nat-games">
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<para>Why do most games not work with the
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<option>-nat</option> switch?</para>
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</question>
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<answer>
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<para>The reason games and the like do not work when
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&man.libalias.3; is in use is that the machine on the
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outside will try to open a connection or send
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(unsolicited) UDP packets to the machine on the inside.
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The NAT software does not know that it should send these
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packets to the interior machine.</para>
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<para>To make things work, make sure that the only thing
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running is the software that you are having problems with,
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then either run &man.tcpdump.1; on the &man.tun.4;
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interface of the gateway or enable &man.ppp.8; TCP/IP
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logging (<literal>set log +tcp/ip</literal>) on the
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gateway.</para>
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<para>When you start the offending software, you should see
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packets passing through the gateway machine. When
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something comes back from the outside, it will be dropped
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(that is the problem). Note the port number of these
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packets then shut down the offending software. Do this a
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few times to see if the port numbers are consistent. If
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they are, then the following line in the relevant section
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of <filename>/etc/ppp/ppp.conf</filename> will make the
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software functional:</para>
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<programlisting>nat port <replaceable>proto</replaceable> <replaceable>internalmachine</replaceable>:<replaceable>port</replaceable> <replaceable>port</replaceable></programlisting>
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<para>where <replaceable>proto</replaceable> is either
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<literal>tcp</literal> or <literal>udp</literal>,
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<replaceable>internalmachine</replaceable> is the machine
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that you want the packets to be sent to and
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<replaceable>port</replaceable> is the destination port
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number of the packets.</para>
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<para>You will not be able to use the software on other
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machines without changing the above command, and running
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the software on two internal machines at the same time is
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out of the question — after all, the outside world
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is seeing your entire internal network as being just a
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single machine.</para>
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<para>If the port numbers are not consistent, there are
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three more options:</para>
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<orderedlist>
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<listitem>
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<para>Submit support in &man.libalias.3;. Examples of
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<quote>special cases</quote> can be found in
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<filename>/usr/src/sys/netinet/libalias/alias_*.c</filename>
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(<filename>alias_ftp.c</filename> is a good
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prototype). This usually involves reading certain
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recognized outgoing packets, identifying the
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instruction that tells the outside machine to initiate
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a connection back to the internal machine on a
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specific (random) port and setting up a
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<quote>route</quote> in the alias table so that the
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subsequent packets know where to go.</para>
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<para>This is the most difficult solution, but it is the
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best and will make the software work with multiple
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machines.</para>
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</listitem>
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<listitem>
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<para>Use a proxy. The application may support
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<literal>socks5</literal> for example, or may have a
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<quote>passive</quote> option that avoids ever
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requesting that the peer open connections back to the
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local machine.</para>
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</listitem>
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<listitem>
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<para>Redirect everything to the internal machine using
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<literal>nat addr</literal>. This is the
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sledge-hammer approach.</para>
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</listitem>
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</orderedlist>
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</answer>
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</qandaentry>
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<qandaentry>
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<question xml:id="fcs-errors">
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<para>What are FCS errors?</para>
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