Chapter 34. Analysing and solving samba problems

+There are many sources of information available in the form +of mailing lists, RFC's and documentation. The docs that come +with the samba distribution contain very good explanations of +general SMB topics such as browsing.

Diagnostics tools

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 sniffer. A sniffer is a program that +listens on your LAN, analyses the data sent on it and displays it +on the screen.

Debugging with Samba itself

+One of the best diagnostic tools for debugging problems is Samba itself. +You can use the -d option for both smbd and nmbd to specify what +debug level at which to run. See the man pages on smbd, nmbd and +smb.conf for more information on debugging options. The debug +level can range from 1 (the default) to 10 (100 for debugging passwords). +

+Another helpful method of debugging is to compile samba using the +gcc -g flag. This will include debug +information in the binaries and allow you to attach gdb to the +running smbd / nmbd process. In order to attach gdb to an smbd +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, on the first time you join the domain) to +generate a 'LsaEnumTrustedDomains'. Thereafter, the workstation +maintains an open connection, and therefore there will be an smbd +process running (assuming that you haven't set a really short smbd +idle timeout) So, in between pressing ctrl alt delete, and actually +typing in your password, you can attach gdb and continue. +

+Some useful samba commands worth investigating: +

+$ testparm | more
+$ smbclient -L //{netbios name of server}
+

Tcpdump

Tcpdump was the first +unix sniffer with SMB support. It is a command-line utility and +nowadays, it's SMB support is somewhat less then that of ethereal +and tethereal.

Ethereal

+Ethereal is a graphical +sniffer, available for both unix (Gtk) and Windows. Ethereal's +SMB support is very good.

For details on the use of ethereal, read the well-written +ethereal User Guide.

+Listen for data on ports 137, 138, 139 and 445. E.g. +use the filter port 137 or port 138 or port 139 or port 445.

A console version of ethereal is available as well and is called +tethereal.

The Windows Network Monitor

+For tracing things on the Microsoft Windows NT, Network Monitor +(aka. netmon) is available on the Microsoft Developer Network CD's, +the Windows NT Server install CD and the SMS CD's. 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. +

Installing 'Network Monitor' on an NT Workstation

+Installing netmon on an NT workstation requires a couple +of steps. The following are 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 / Netmon. You will need both the Microsoft Windows +NT Server 4.0 Install CD and the Workstation 4.0 Install CD. +

+Initially you will need to install Network Monitor Tools and Agent +on the NT Server. To do this +

Goto Start - Settings - Control Panel - + Network - Services - Add
Select the Network Monitor Tools and Agent and + click on OK.
Click OK on the Network Control Panel. +
Insert the Windows NT Server 4.0 install CD + when prompted.

+At this point the Netmon files should exist in +%SYSTEMROOT%\System32\netmon\*.*. +Two subdirectories exist as well, parsers\ +which contains the necessary DLL's for parsing the netmon packet +dump, and captures\. +

+In order to install the Netmon tools on an NT Workstation, you will +first need to install the 'Network Monitor Agent' from the Workstation +install CD. +

Goto Start - Settings - Control Panel - + Network - Services - Add
Select the Network Monitor Agent and click + on OK.
Click OK on the Network Control Panel. +
Insert the Windows NT Workstation 4.0 install + CD when prompted.

+Now copy the files from the NT Server in %SYSTEMROOT%\System32\netmon\*.* +to %SYSTEMROOT%\System32\netmon\*.* 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. +

Installing 'Network Monitor' on an 9x Workstation

+To install Netmon on a Windows 9x box install the network monitor agent +from the Windows 9x CD (\admin\nettools\netmon). There is a readme +file located 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. +

Useful URLs

See how Scott Merrill simulates a BDC behavior at + + http://www.skippy.net/linux/smb-howto.html.
FTP site for older SMB specs: + + ftp://ftp.microsoft.com/developr/drg/CIFS/

Getting help from the mailing lists

+There are a number of Samba related mailing lists. Go to http://samba.org, click on your nearest mirror +and then click on Support and then click on +Samba related mailing lists. +

+For questions relating to Samba TNG go to +http://www.samba-tng.org/ +It has been requested that you don't post questions about Samba-TNG to the +main stream Samba lists.

+If you post a message to one of the lists please observe the following guide lines : +

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 time lines are 'best guess' and nothing more. +
Always mention what version of samba you are using and what +operating system its running under. You should probably list the +relevant sections of your smb.conf file, at least the options +in [global] that affect PDC support.
In addition to the version, if you obtained Samba via +CVS mention the date when you last checked it out.
Try and make your question clear and brief, lots of long, +convoluted questions get deleted before they are completely read ! +Don't post html encoded messages (if you can select colour or font +size its html).
If you run one of those nifty 'I'm on holidays' things when +you are away, make sure its configured to not answer mailing lists. +
Don't cross post. Work out which is the best list to post to +and see what happens, i.e. don't 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 will see a message and thinking it would be better dealt +with on another, will forward it on for you.
You might include partial +log files written at a debug level set to as much as 20. +Please don't send the entire log but enough to give the context of the +error messages.
(Possibly) If you have a complete netmon trace ( from the opening of +the pipe to the error ) you can send the *.CAP file as well.
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?

How to get off the mailing lists

To have your name removed from a samba mailing list, go to the +same place you went to to get on it. Go to http://lists.samba.org, +click on your nearest mirror and then click on Support and +then click on Samba related mailing lists. +

+Please don't post messages to the list asking to be removed, you will just +be referred to the above address (unless that process failed in some way...) +

Prev	Up	Next
Chapter 33. The Samba checklist	Home	Chapter 35. Reporting Bugs