s4:smb_server: fix large read_andx requests

[Samba.git] / docs-xml / Samba3-HOWTO / TOSHARG-Problems.xml

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<!DOCTYPE chapter PUBLIC "-//Samba-Team//DTD DocBook V4.2-Based Variant V1.0//EN" "http://www.samba.org/samba/DTD/samba-doc">
<chapter id="problems">

<chapterinfo>
        &author.jerry;
        &author.jelmer;
        &author.dbannon;
        &author.danshearer;
        <pubdate>8 Apr 2003</pubdate>
</chapterinfo>

<title>Analyzing and Solving Samba Problems</title>

<para>
<indexterm><primary>RFCs</primary></indexterm>
<indexterm><primary>SMB</primary></indexterm>
<indexterm><primary>documentation</primary></indexterm>
There are many sources of information available in the form of mailing lists, RFCs, and documentation. The
documentation that comes with the Samba distribution contains good explanations of general SMB topics such as
browsing.
</para> 
        
<sect1>
<title>Diagnostics Tools</title>

<para>
<indexterm><primary>sniffer</primary></indexterm>
<indexterm><primary>LAN</primary></indexterm>
<indexterm><primary>analyzes data</primary></indexterm>
<indexterm><primary>SMB networking</primary></indexterm>
<indexterm><primary>network analyzer</primary></indexterm>
With SMB networking, it is often not immediately clear what the cause is of a certain problem. Samba itself
provides rather useful information, but in some cases you might have to fall back to using a
<emphasis>sniffer</emphasis>. A sniffer is a program that listens on your LAN, analyzes the data sent on it,
and displays it on the screen.
</para>

<sect2>
<title>Debugging with Samba Itself</title>

<para>
<indexterm><primary>diagnostic tools</primary></indexterm>
<indexterm><primary>debugging problems</primary></indexterm>
<indexterm><primary>smbd</primary></indexterm>
<indexterm><primary>nmbd</primary></indexterm>
<indexterm><primary>debugging passwords</primary></indexterm>
<indexterm><primary>debug level</primary></indexterm>
<indexterm><primary>log level</primary></indexterm>
One of the best diagnostic tools for debugging problems is Samba itself.  You can use the <option>-d
option</option> for both &smbd; and &nmbd; to specify the <smbconfoption name="debug level"/> at which to run.
See the man pages for <command>smbd, nmbd</command>, and &smb.conf; for more information regarding debugging
options. The debug level (log level) can range from 1 (the default) to 10 (100 for debugging passwords).
</para>
        
<para>
<indexterm><primary>debugging</primary></indexterm>
<indexterm><primary>gcc</primary></indexterm>
<indexterm><primary>gdb</primary></indexterm>
<indexterm><primary>smbd</primary></indexterm>
<indexterm><primary>nmbd</primary></indexterm>
<indexterm><primary>LsaEnumTrustedDomains</primary></indexterm>
<indexterm><primary>attach gdb</primary></indexterm>
Another helpful method of debugging is to compile Samba using the <command>gcc -g </command> flag. This will
include debug information in the binaries and allow you to attach <command>gdb</command> to the running
<command>smbd/nmbd</command> process.  To attach <command>gdb</command> to an <command>smbd</command> process
for an NT workstation, first get the workstation to make the connection. Pressing ctrl-alt-delete and going
down to the domain box is sufficient (at least, the first time you join the domain) to generate a
<parameter>LsaEnumTrustedDomains</parameter>. Thereafter, the workstation maintains an open connection and
there will be an smbd process running (assuming that you haven't set a really short smbd idle timeout). So, in
between pressing <command>ctrl-alt-delete</command> and actually typing in your password, you can attach
<command>gdb</command> and continue.
</para>

<para>
Some useful Samba commands worth investigating are:
<indexterm><primary>testparm</primary></indexterm>
<indexterm><primary>smbclient</primary></indexterm>
<screen>
&prompt;<userinput>testparm | more</userinput>
&prompt;<userinput>smbclient -L //{netbios name of server}</userinput>
</screen>
</para>

</sect2>

<sect2>
        <title>Tcpdump</title>
  
<para>
<indexterm><primary>tcpdump</primary></indexterm>
<indexterm><primary>tethereal</primary></indexterm>
<indexterm><primary>ethereal</primary></indexterm>
<ulink url="http://www.tcpdump.org/">Tcpdump</ulink> was the first 
UNIX sniffer with SMB support. It is a command-line utility and 
now, its SMB support is somewhat lagging that of <command>ethereal</command> 
and <command>tethereal</command>.
</para>

</sect2>

<sect2>
        <title>Ethereal</title>

<para>
<indexterm><primary>ethereal</primary></indexterm>
<ulink url="http://www.ethereal.com/">Ethereal</ulink> is a graphical sniffer, available for both UNIX (Gtk)
and Windows. Ethereal's SMB support is quite good. For details on the use of <command>ethereal</command>, read
the well-written Ethereal User Guide.
</para>

<figure id="ethereal1"><title>Starting a Capture.</title><imagefile>ethereal1</imagefile></figure>

<para>
<indexterm><primary>ports</primary></indexterm>
Listen for data on ports 137, 138, 139, and 445. For example, use the filter <userinput>port 137, port 138,
port 139, or port 445</userinput> as seen in <link linkend="ethereal1">Starting a Capture</link> snapshot.
</para>

<para>
A console version of ethereal is available as well and is called <command>tethereal</command>.
</para>

<figure id="ethereal2"><title>Main Ethereal Data Window.</title><imagefile>ethereal2</imagefile></figure>

</sect2>

<sect2>
<title>The Windows Network Monitor</title>
        
<para>
<indexterm><primary>Network Monitor</primary></indexterm>
<indexterm><primary>Netmon</primary></indexterm>
<indexterm><primary>Microsoft Developer Network CDs</primary></indexterm>
<indexterm><primary>SMS</primary></indexterm>
<indexterm><primary>promiscuous mode</primary></indexterm>
<indexterm><primary>ethereal</primary></indexterm>
For tracing things on Microsoft Windows NT, Network Monitor (aka Netmon) is available on Microsoft Developer
Network CDs, the Windows NT Server install CD, and the SMS CDs. The version of Netmon that ships with SMS
allows for dumping packets between any two computers (i.e., placing the network interface in promiscuous
mode).  The version on the NT Server install CD will only allow monitoring of network traffic directed to the
local NT box and broadcasts on the local subnet. Be aware that Ethereal can read and write Netmon formatted
files.
</para>

<sect3>
<title>Installing Network Monitor on an NT Workstation</title>

<para>
<indexterm><primary>Netmon.</primary></indexterm>
Installing Netmon on an NT workstation requires a couple of steps. The following are instructions for
installing Netmon V4.00.349, which comes with Microsoft Windows NT Server 4.0, on Microsoft Windows NT
Workstation 4.0. The process should be similar for other versions of Windows NT version of Netmon. You will
need both the Microsoft Windows NT Server 4.0 Install CD and the Workstation 4.0 Install CD.
</para> 

<para>
<indexterm><primary>Network Monitor Tools and Agent</primary></indexterm>
Initially you will need to install <application>Network Monitor Tools and Agent</application>
on the NT Server to do this: 
</para>

<itemizedlist>
        <listitem><para>Go to <guibutton>Start</guibutton> -> <guibutton>Settings</guibutton> -> <guibutton>Control Panel</guibutton> -> 
        <guibutton>Network</guibutton> -> <guibutton>Services</guibutton> -> <guibutton>Add</guibutton>.</para></listitem>
        
        <listitem><para>Select the <guilabel>Network Monitor Tools and Agent</guilabel> and click on <guibutton>OK</guibutton>.</para></listitem> 
        
        <listitem><para>Click on <guibutton>OK</guibutton> on the Network Control Panel.</para></listitem> 
        
        <listitem><para>Insert the Windows NT Server 4.0 install CD when prompted.</para></listitem> 
</itemizedlist>

<para>
At this point, the Netmon files should exist in <filename>%SYSTEMROOT%\System32\netmon\*.*</filename>.   
Two subdirectories exist as well: <filename>parsers\</filename>, which contains the necessary DLLs
for parsing the Netmon packet dump, and <filename>captures\</filename>.
</para>

<para>
To install the Netmon tools on an NT Workstation, you will first need to install the 
Network  Monitor Agent from the Workstation install CD.
</para>

<itemizedlist>
        <listitem><para>Go to <guibutton>Start</guibutton> -> <guibutton>Settings</guibutton> ->
                <guibutton>Control Panel</guibutton> -> <guibutton>Network</guibutton> ->
                <guibutton>Services</guibutton> -> <guibutton>Add</guibutton>.</para></listitem> 

        <listitem><para>Select the <guilabel>Network Monitor Agent</guilabel>, click on
                <guibutton>OK</guibutton>.</para></listitem> 
        
        <listitem><para>Click on <guibutton>OK</guibutton> in the Network Control Panel.
        </para></listitem> 
        
        <listitem><para>Insert the Windows NT Workstation 4.0 install CD when prompted.</para></listitem> 
</itemizedlist>

<para>
Now copy the files from the NT Server in <filename>%SYSTEMROOT%\System32\netmon</filename>
to <filename>%SYSTEMROOT%\System32\netmon</filename> on the workstation and set permissions
as you deem appropriate for your site. You will need administrative rights on the NT box to run Netmon.
</para>

</sect3>
<sect3>
<title>Installing Network Monitor on Windows 9x/Me</title>
<para>
To install Netmon on Windows 9x/Me, install the Network Monitor Agent 
from the Windows 9x/Me CD (<filename>\admin\nettools\netmon</filename>). 
There is a readme file included with the Netmon driver files on the CD if you need 
information on how to do this. Copy the files from a working Netmon installation.
</para>
</sect3>
</sect2>
</sect1>

<sect1>
<title>Useful URLs</title>
<itemizedlist>

<listitem><para>FTP site for older SMB specs, 
       <ulink noescape="1" url="ftp://ftp.microsoft.com/developr/drg/CIFS/">
       ftp://ftp.microsoft.com/developr/drg/CIFS/</ulink></para></listitem>.

</itemizedlist>

</sect1>

<sect1>
<title>Getting Mailing List Help</title>

<para>
There are a number of Samba-related mailing lists. Go to <ulink 
noescape="1" url="http://samba.org">http://samba.org</ulink>, click on your nearest mirror,
and then click on <command>Support</command>. Next, click on <command>
Samba-related mailing lists</command>.
</para>

<para>
For questions relating to Samba TNG, go to
<ulink noescape="1" url="http://www.samba-tng.org/">http://www.samba-tng.org/</ulink>. 
It has been requested that you do not post questions about Samba-TNG to the
mainstream Samba lists.</para>

<para>
If you do post a message to one of the lists, please observe the following guidelines:
</para>

<itemizedlist>

        <listitem><para>
<indexterm><primary>volunteers</primary></indexterm>
        Always remember that the developers are volunteers; they are
        not paid and they never guarantee to produce a particular feature at 
        a particular time. Any timelines are <quote>best guess,</quote> and nothing more.
        </para></listitem>

        <listitem><para>
<indexterm><primary>PDC</primary></indexterm>
        Always mention what version of Samba you are using and what 
        operating system it's running under. You should list the relevant sections of
        your &smb.conf; file, at least the options in <smbconfsection name="[global]"/>
        that affect PDC support.
        </para></listitem>

        <listitem><para>In addition to the version, if you obtained Samba via
        CVS, mention the date when you last checked it out.</para></listitem>

        <listitem><para> Try to make your questions clear and brief. Lots of long, 
        convoluted questions get deleted before they are completely read!
        Do not post HTML-encoded messages. Most people on mailing lists simply delete
        them.
        </para></listitem>

        <listitem><para> If you run one of those nifty <quote>I'm on holiday</quote> things when
        you are away, make sure its configured to not answer mailing list traffic. Autoresponses
        to mailing lists really irritate the thousands of people who end up having to deal
        with such bad netiquet bahavior.
        </para></listitem> 

        <listitem><para>
<indexterm><primary>cross post</primary></indexterm>
        Don't cross post. Work out which is the best list to post to 
        and see what happens. Do not post to both samba-ntdom and samba-technical.
        Many people active on the lists subscribe to more 
        than one list and get annoyed to see the same message two or more times.
        Often someone who thinks a message would be better dealt 
        with on another list will forward it on for you.</para></listitem>

        <listitem><para>You might include <emphasis>partial</emphasis>
        log files written at a log level set to as much as 20. 
        Please do not send the entire log but just enough to give the context of the
        error messages.</para></listitem>

        <listitem><para>If you have a complete Netmon trace (from the opening of
        the pipe to the error), you can send the *.CAP file as well.</para></listitem> 
            
        <listitem><para>Please think carefully before attaching a document to an email.
        Consider pasting the relevant parts into the body of the message. The Samba
        mailing lists go to a huge number of people. Do they all need a copy of your 
        &smb.conf; in their attach directory?</para></listitem>

</itemizedlist>

</sect1>

<sect1>
<title>How to Get Off the Mailing Lists</title>

<para>To have your name removed from a Samba mailing list, go to the same
place where you went to
subscribe to it, go to <ulink noescape="1" url="http://lists.samba.org/">http://lists.samba.org</ulink>, 
click on your nearest mirror, click on <command>Support</command>, and 
then click on <command>Samba-related mailing lists</command>. 
</para>

<para>
Please do not post messages to the list asking to be removed. You will only
be referred to the above address (unless that process failed in some way).
</para>

</sect1>

</chapter>