Samba
Overview
Samba is a program which allows "Network Neighborhood"-style communication between Windows and other platforms such as Linux. It is named after the SMB protocol, which is what Windows uses for "Network Neighborhood" communication.
Commands
- User commands
- System commands (not usually run by the user)
Related Articles
How To
Debug connection/access issues
Samba maintains activity logs in /var/log/samba/. There seem to be two logs, log.nmbd and log.smbd; log.smbd generally has information about connections and access, while log.nmbd has more to to with network-name resolution. The nature of the log files is configurable somewhat through smb.conf (see log level, among others). Use tail -f /var/log/samba/log.smbd (for example) to monitor a logfile in real-time.
Restart the Samba Server
If you have Fedora Core, there's a convenient little "services" application you can use to restart Samba and several dozen other services. For the rest of us, however, there's a command you have to execute from a root terminal.
On Ubuntu, and probably other Debian-based systems:
sudo /etc/init.d/samba restart
On SuSE 10.0 and Fedora Core 4:
sudo /etc/init.d/smb restart
This will ask for a password; type in your password (not root's) unless you have reconfigured your sudo setup. (This assumes you have sudo privileges; if not, su to get root access and then type the rest of the command without the "sudo".)
On Red Hat, I'm told the command would be:
/sbin/samba restart
(Possibly substituting "smb" for "samba"; ls the directory in question to find a list of services.) This is the same general technique used for restarting services, which should itself probably be documented somewhere. (The Samba share configuration GUI program really ought to have a "restart Samba server" button, though, even if it does this automatically when you change parameters -- because there is no way to know if it is doing this otherwise.)
Configure Samba for "guest" logins
As most home operating systems are now moving towards requiring users to have login accounts, this is becoming less necessary -- but it is still useful under some circumstances (such as wanting to give access to Win9x machines with the login dialogue bypassed).
Configuration for smb.conf:
In the [global] section:
# Causes Samba to act as WINS server, which turns network names into IP addresses. wins support = yes # Causes Samba to act as Local Master Browser # (This can help prevent conflicts between XP and 9x, where XP tends to take over and refuse access to non-XP systems) local master = yes # These may or may not be important, but it's how my system is set: socket options = TCP_NODELAY SO_RCVBUF=8192 SO_SNDBUF=8192 winbind uid = 16777216-33554431 winbind gid = 16777216-33554431
guest account = sambaguest password server = None guest ok = yes security = SHARE username map = /etc/samba/smbusers
# these options help to prevent permissions conflicts # (where the "sambaguest" user creates files which (by default) nobody else can write or delete) force group = lanusers force create mode = 0060 create mask = 0775
I haven't tested these to see if these options are all helpful or if there are other options which are necessary; this is just a first pass based on a combination of (vague) understanding and actual experience.
After editing and saving smb.conf. restart the Samba daemon for changes to take effect.
Tentative explanation of "guest" status: SMB has the concept of a "guest account", which is what Win9x uses by default when connecting via SMB (if you set up user logins, then I think it uses the actual username, but I haven't tested this); the "guest account" setting is the user which Samba appears to be when the SMB "guest account" is accessing files. In other words, for example: files created by a SMB "guest account" will appear on a Linux system as created by "sambaguest". If the "force group" setting is used, then those files will also be owned by the specified group.
Automatic resolution of Network Neighborhood names
(I researched this extensively for many months, but all the solutions I found were either hideously complicated or somehow inadequate. The solution turns out to be quite simple.)
Some explanation, for technical purists:
- Problem: How can we add Network Neighborhood machine names to the search space used by Linux's domain name resolver?
- Justification: This is needed so that commands which accept a domain name as input (e.g. ftp, ssh, mysql) can accept a machine name instead, removing the necessity to manually look up the machine's IP address. For example, I should be able to type ssh machinename instead of having to first look up machinename's IP address via other methods, and then paste or retype that address (both methods prone to error) after the ssh command.
The solution:
- install winbind (usually available in standard repositories; Ubuntu has it)
- edit /etc/nsswitch.conf
- change the "hosts" line to include "wins" before "dns".
This tells Linux's domain name resolver to check WINS before it checks DNS when resolving domain names.
The command nmblookup machinename returns an IP address, as will net lookup machinename. nmblookup apparently sends out a broadcast request ("anyone here named machinename?"), while net lookup checks a central list (presumably on the Samba master browser).
notes
WINS is a method of domain name resolution, as is DNS. WINS (a protocol) originally used NetBIOS (another, lower-level protocol), but more recently has switched to using TCP.
Reference
- Wikipedia:Samba software
- Wikipedia:Server Message Block: SMB protocol
Links
- Managing Samba: Choose your weapon -- Windows network ID basics: seems to cover some useful concepts