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<A HREF="mpd.html"><EM>Mpd 5.9 User Manual</EM></A>
<b>:</b> <A HREF="mpd62.html"><EM>Troubleshooting</EM></A>
<b>:</b> <EM>Troubleshooting</EM><BR>
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<H2><A NAME="63"></A>7.1. Troubleshooting<A NAME="trouble"></A></H2>
<p>Some tips for troubleshooting.</p>
<p>For further help, ask to the <code>freebsd-net@freebsd.org</code>
mailing list or sourceforge.net mpd project forum.</p>
<p>
<dl>
<dt><b><b>It does not work and I do not understand why.</b></b><dd><p>Mpd has extensive logging system supporting syslog. To direct logs
into a file add lines
<pre>
!mpd
*.* /var/log/mpd.log
</pre>
into your /etc/syslog.conf file, create /var/log/mpd.log file and send
SIGHUP to syslogd to reread config.</p>
<p>To enable all possible logging you can use 'log +all' command.</p>
<dt><b><b>Packets won't flow.</b></b><dd><p>Make sure you have set <code><b>gateway_enable="YES"</b></code>
in <code>/etc/rc.conf</code>, otherwise your FreeBSD box will not
route packets.</p>
<p>Also, check your firewall settings. Mpd will create new interfaces
which may need to be incorporated into your firewall rules.
If you're doing PPTP, you need to allow TCP port 1723 and IP protocol
47 (GRE).</p>
<dt><b><b>It does not work and there are strange netgraph-related errors in the log.</b></b><dd><p>Make sure you have all the required netgraph KLD's loaded.
You can check them by doing <code> kldstat -v | grep ng_ </code>.</p>
<p>Usually these are loaded on demand. If not, you can load them
manually using <code>kldload(8)</code>.</p>
<p>The following node types are or may be needed:</p>
<p>
<ul>
<li><code>ng_async</code></li>
<li><code>ng_bpf</code></li>
<li><code>ng_car</code></li>
<li><code>ng_deflate</code></li>
<li><code>ng_ether</code></li>
<li><code>ng_iface</code></li>
<li><code>ng_ksocket</code></li>
<li><code>ng_l2tp</code></li>
<li><code>ng_mppc</code></li>
<li><code>ng_ppp</code></li>
<li><code>ng_pppoe</code></li>
<li><code>ng_pptpgre</code></li>
<li><code>ng_nat</code></li>
<li><code>ng_netflow</code></li>
<li><code>ng_pred1</code></li>
<li><code>ng_socket</code></li>
<li><code>ng_tcpmss</code></li>
<li><code>ng_tee</code></li>
<li><code>ng_tty</code></li>
<li><code>ng_vjc</code></li>
</ul>
</p>
<dt><b><b>My configuration does not seem to be working as expected.</b></b><dd><p>Make sure your <code>mpd.conf</code> file formatted properly.
Labels must be left-justified, while other lines must not.</p>
<dt><b><b>I am getting no valid response from the RADIUS server.</b></b><dd><p>Double-check the shared secret in the RADIUS servers config and the
one specified in <code>mpd.conf</code> or <code>radius.conf</code>.
Check the ports of the RADIUS server: they should be 1812 (authentication)
and 1813 (accounting), wich are also the default ports of mpd. In
the past unofficial port numbers (1645 and 1646) were used for RADIUS,
but these are deprecated.</p>
<dt><b><b>I am getting ``Operation not permitted'' errors trying to run mpd.</b></b><dd><p>This is often caused by a combination of (a) using netgraph in KLD module
form instead of statically compiling the various modules into the kernel
via kernel <code>config(8)</code> options, and (b) increasing your
kernel security level (see the <code>init(8)</code> man page), which prevents
KLD modules from being loaded. Change one of these things to fix the problem.</p>
<dt><b><b>I have configured a link for dial-in and sometimes after disconnecting
mpd gets into some kind of infinite loop.</b></b><dd><p>This is because mpd is trying to ``redial'' which of course is not
appropriate for dial-in links. Use <code>set link max-redial -1</code> and
<code>set bundle yes noretry</code> to disable the redial function.</p>
<dt><b><b>I use mpd as PPTP server for Windows XP clients. While accessing bigger
websites or listing larger ftp directories the connection
seems to hang.</b></b><dd><p>Windows XP insists on a very low MTU (usually 1396 Bytes). This needs
fragmentation if bigger packets should be transmitted over the link.
Fragmentation is negotiated at ICMP level. If there is a bad router
somewhere in the network dropping such packets then the connection
hangs.
The first thing what you can try is reducing mpd's MTU value, by
setting: <code>set link mtu 1300</code> and <code>set bundle disable multilink</code>,
this should help in most cases.
For TCP connections it is possible enabling the TCP-MSS-Fix:
<code>set iface enable tcpmssfix</code>.</p>
<dt><b><b>Problems with MPPE stateless when connecting to Cisco devices.</b></b><dd><p>Upgrade the IOS of your device, see:
<code>CSCdu30944 MPPE rejects stateless Fixed in 12.3(11.4)</code></p>
</dl>
</p>
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