Procedure 36.1. Diagnosing your Samba server

1. In the directory in which you store your smb.conf file, run the command testparm smb.conf. If it reports any errors, then your smb.conf configuration file is faulty.

   Note

   Your smb.conf file may be located in: /etc/samba or in /usr/local/samba/lib.

2. Run the command ping BIGSERVER from the PC and ping ACLIENT from the UNIX box. If you do not get a valid response, then your TCP/IP software is not correctly installed.

   You will need to start a “dos prompt” window on the PC to run ping.

   If you get a message saying “host not found” or similar, then your DNS software or /etc/hosts file is not correctly setup. It is possible to run Samba without DNS entries for the server and client, but it is assumed you do have correct entries for the remainder of these tests.

   Another reason why ping might fail is if your host is running firewall software. You will need to relax the rules to let in the workstation in question, perhaps by allowing access from another subnet (on Linux this is done via the appropriate firewall maintenance commands ipchains or iptables).

   Note

   Modern Linux distributions install ipchains/iptables by default. This is a common problem that is often overlooked.

   If you wish to check what firewall rules may be present in a system under test, simply run iptables -L -v or if ipchains-based firewall rules are in use, ipchains -L -v.

   Here is a sample listing from a system that has an external ethernet interface (eth1) on which Samba is not active, and an internal (private network) interface (eth0) on which Samba is active:

   frodo:~ # iptables -L -v
   Chain INPUT (policy DROP 98496 packets, 12M bytes)
    pkts bytes target     prot opt in     out     source     destination
    187K  109M ACCEPT     all  --  lo     any     anywhere   anywhere
    892K  125M ACCEPT     all  --  eth0   any     anywhere   anywhere
   1399K 1380M ACCEPT     all  --  eth1   any     anywhere   anywhere  \
   					state RELATED,ESTABLISHED
   
   Chain FORWARD (policy DROP 0 packets, 0 bytes)
    pkts bytes target     prot opt in     out     source     destination
    978K 1177M ACCEPT     all  --  eth1   eth0    anywhere   anywhere \
   					state RELATED,ESTABLISHED
    658K   40M ACCEPT     all  --  eth0   eth1    anywhere   anywhere
       0     0 LOG        all  --  any    any     anywhere   anywhere \
   					LOG level warning
   
   Chain OUTPUT (policy ACCEPT 2875K packets, 1508M bytes)
    pkts bytes target     prot opt in     out     source     destination
   
   Chain reject_func (0 references)
    pkts bytes target     prot opt in     out     source     destination
   

3. Run the command: smbclient -L BIGSERVER on the UNIX box. You should get back a list of available shares.

   If you get an error message containing the string “Bad password”, then you probably have either an incorrect hosts allow, hosts deny or valid users line in your smb.conf, or your guest account is not valid. Check what your guest account is using testparm and temporarily remove any hosts allow, hosts deny, valid users or invalid users lines.

   If you get a message “connection refused” response, then the smbd server may not be running. If you installed it in inetd.conf, then you probably edited that file incorrectly. If you installed it as a daemon, then check that it is running, and check that the netbios-ssn port is in a LISTEN state using netstat -a.

   Note

   Some UNIX/Linux systems use xinetd in place of inetd. Check your system documentation for the location of the control files for your particular system implementation of the network super daemon.

   If you get a message saying “session request failed”, the server refused the connection. If it says “Your server software is being unfriendly”, then it's probably because you have invalid command line parameters to smbd, or a similar fatal problem with the initial startup of smbd. Also check your config file (smb.conf) for syntax errors with testparm and that the various directories where Samba keeps its log and lock files exist.

   There are a number of reasons for which smbd may refuse or decline a session request. The most common of these involve one or more of the smb.conf file entries as shown in the next example.

   Example 36.2. Configuration for only allowing connections from a certain subnet

   [globals]

   ...

   hosts deny = ALL

   hosts allow = xxx.xxx.xxx.xxx/yy

   interfaces = eth0

   bind interfaces only = Yes

   ...

   In the above, no allowance has been made for any session requests that will automatically translate to the loopback adapter address 127.0.0.1. To solve this problem, change these lines as shown in the following example.

   Example 36.3. Configuration for allowing connections from a certain subnet and localhost

   [globals]

   ...

   hosts deny = ALL

   hosts allow = xxx.xxx.xxx.xxx/yy 127.

   interfaces = eth0 lo

   ...

   Another common cause of these two errors is having something already running on port 139, such as Samba (smbd is running from inetd already) or something like Digital's Pathworks. Check your inetd.conf file before trying to start smbd as a daemon it can avoid a lot of frustration!

   And yet another possible cause for failure of this test is when the subnet mask and/or broadcast address settings are incorrect. Please check that the network interface IP Address/Broadcast Address/Subnet Mask settings are correct and that Samba has correctly noted these in the log.nmbd file.

4. Run the command: nmblookup -B BIGSERVER __SAMBA__. You should get back the IP address of your Samba server.

   If you do not, then nmbd is incorrectly installed. Check your inetd.conf if you run it from there, or that the daemon is running and listening to udp port 137.

   One common problem is that many inetd implementations can't take many parameters on the command line. If this is the case, then create a one-line script that contains the right parameters and run that from inetd.

5. Run the command: nmblookup -B ACLIENT `*'

   You should get the PC's IP address back. If you do not then the client software on the PC isn't installed correctly, or isn't started, or you got the name of the PC wrong.

   If ACLIENT does not resolve via DNS then use the IP address of the client in the above test.

6. Run the command: nmblookup -d 2 '*'

   This time we are trying the same as the previous test but are trying it via a broadcast to the default broadcast address. A number of NetBIOS/TCP/IP hosts on the network should respond, although Samba may not catch all of the responses in the short time it listens. You should see the “got a positive name query response” messages from several hosts.

   If this does not give a similar result to the previous test, then nmblookup isn't correctly getting your broadcast address through its automatic mechanism. In this case you should experiment with the interfaces option in smb.conf to manually configure your IP address, broadcast and netmask.

   If your PC and server aren't on the same subnet, then you will need to use the -B option to set the broadcast address to that of the PCs subnet.

   This test will probably fail if your subnet mask and broadcast address are not correct. (Refer to TEST 3 notes above).

7. Run the command: smbclient //BIGSERVER/TMP. You should then be prompted for a password. You should use the password of the account with which you are logged into the UNIX box. If you want to test with another account, then add the -U accountname option to the end of the command line. For example, smbclient //bigserver/tmp -Ujohndoe.

   Note

   It is possible to specify the password along with the username as follows: smbclient //bigserver/tmp -Ujohndoe%secret.

   Once you enter the password, you should get the smb> prompt. If you do not, then look at the error message. If it says “invalid network name”, then the service tmp is not correctly setup in your smb.conf.

   If it says “bad password”, then the likely causes are:

   1. You have shadow passwords (or some other password system) but didn't compile in support for them in smbd.

   2. Your valid users configuration is incorrect.

   3. You have a mixed case password and you haven't enabled the password level option at a high enough level.

   4. The path line in smb.conf is incorrect. Check it with testparm.

   5. You enabled password encryption but didn't map UNIX to Samba users. Run: smbpasswd -a username

   Once connected, you should be able to use the commands dir, get, put and so on. Type help command for instructions. You should especially check that the amount of free disk space shown is correct when you type dir.

8. On the PC, type the command net view \\BIGSERVER. You will need to do this from within a dos prompt window. You should get back a list of shares available on the server.

   If you get a message “network name not found” or similar error, then netbios name resolution is not working. This is usually caused by a problem in nmbd. To overcome it, you could do one of the following (you only need to choose one of them):

   1. Fixup the nmbd installation.

   2. Add the IP address of BIGSERVER to the wins server box in the advanced TCP/IP setup on the PC.

   3. Enable Windows name resolution via DNS in the advanced section of the TCP/IP setup.

   4. Add BIGSERVER to your lmhosts file on the PC.

   If you get a message “invalid network name” or “bad password error”, then apply the same fixes as for the smbclient -L test above. In particular, make sure your hosts allow line is correct (see the man pages).

   Also, do not overlook that fact that when the workstation requests the connection to the Samba server, it will attempt to connect using the name with which you logged onto your Windows machine. You need to make sure that an account exists on your Samba server with that exact same name and password.

   If you get a message “specified computer is not receiving requests” or similar, it probably means that the host is not contact-able via TCP services. Check to see if the host is running TCP wrappers, and if so add an entry in the hosts.allow file for your client (or subnet, and so on.)

9. Run the command net use x: \\BIGSERVER\TMP. You should be prompted for a password, then you should get a command completed successfully message. If not, then your PC software is incorrectly installed or your smb.conf is incorrect. Make sure your hosts allow and other config lines in smb.conf are correct.

   It's also possible that the server can't work out what user name to connect you as. To see if this is the problem, add the line user = username to the [tmp] section of smb.conf where username is the username corresponding to the password you typed. If you find this fixes things, you may need the username mapping option.

   It might also be the case that your client only sends encrypted passwords and you have encrypt passwords = no in smb.conf. Change this to "yes" to fix this.

10. Run the command nmblookup -M testgroup where testgroup is the name of the workgroup that your Samba server and Windows PCs belong to. You should get back the IP address of the master browser for that workgroup.

    If you do not, then the election process has failed. Wait a minute to see if it is just being slow, then try again. If it still fails after that, then look at the browsing options you have set in smb.conf. Make sure you have preferred master = yes to ensure that an election is held at startup.

11. From file manager, try to browse the server. Your Samba server should appear in the browse list of your local workgroup (or the one you specified in smb.conf). You should be able to double click on the name of the server and get a list of shares. If you get the error message “invalid password”, you are probably running Windows NT and it is refusing to browse a server that has no encrypted password capability and is in User Level Security mode. In this case, either set security = server and password server = Windows_NT_Machine in your smb.conf file, or make sure encrypt passwords is set to “yes”.