Configuring and Managing MPE/iX Internet Services > Chapter 7 Samba/iX Services

Overview of Samba/iX

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Samba/iX is a suite of programs which allow an HP 3000 running MPE/iX operating system to provide service using a Microsoft networking protocol called Server Message Block (SMB). This product allows implementation of interoperability features allowing the system to act as a file and print server to PC clients running the following operation systems:

Microsoft Windows NT
Microsoft Windows 95
Microsoft Windows for Workgroups

Introduction to Samba

Samba is an application of choice allowing interoperability between Windows and UNIX-like systems. It is a group of programs that allows a UNIX host to act as a fileserver for DOS and Windows platforms and also provides print services for them. It is freely available under the GNU Public License. Samba allows UNIX-like machines to be integrated into a Windows network without installing any additional software on the Windows machines. Many different platforms run Samba successfully; and there are nearly forty different operating systems which support Samba.

Features of Samba/iX

As more of our customers implement and configure networking services in a heterogeneous environment of MPE, UNIX, and Windows NT servers, along with Netware, Windows, and NT workstation clients, the need for knowledge in the area of interoperability becomes a must for our customers. Beginning with MPE/iX release 6.0, Samba/iX is available on MPE/iX shell operating system. It allows clients to access a server's filespace and printers via the SMB protocol.

Samba/iX is the result of porting Samba to MPE/iX under POSIX environment. It is a solution for those wishing to access HP 3000 disk storage and printers (both networked and spooled from MPE/iX) from common PC client operating systems like Windows 95 and NT Workstation.Samba/iX allows access to these disk and printer resources of MPE/iX, by providing standard SMB file and printer services that are accessible from PC clients and their applications. It is available to the HP 3000 users with the MPE/iX 6.0 release.

A general UNIX program that is part of the Samba suite has also been ported to MPE/iX shell operating system. This program allows MPE users to use an FTP-like interface to access filespace and printers on any other SMB (Server Message Block) servers. This capability enables these operating systems to act like a LAN server or Windows NT server. See Figure 7-1 "HP 3000 Interoperating With Microsoft Platforms" for HP 3000 interoperating with the Microsoft platforms.

Figure 7-1 HP 3000 Interoperating With Microsoft Platforms

Benefits of Using Samba/iX

There are many benefits in having an MPE/iX and Samba/iX environment, some of which are listed here:

The remote MPE/iX based POSIX filesystem can be browsed as shared/services from PC clients.
Remote files can be operated on as if they are stored locally.
Samba/iX acts as translator between the different file systems for file names and attributes and provides security based on user authentication.
Samba/iX can support the use of long file names by Windows 95 and Windows NT workstation PC clients.
Samba/iX provides seamless interoperability between common desktop operating systems, popular PC applications, and HP 3000 through Microsoft network.

Major Components of Samba/iX

Table 7-1 "Major Components" shows the major components of the Samba/iX suite.

Table 7-1 Major Components

SMBD	The SMB server handles connections from clients, performing all the file, permission, and username authentication.
NMBD	The NetBIOS name server advertises Samba/iX on the network, and helps clients locate servers.
SMBCLIENT	Client program on MPE/iX host.
SMB.CONF	Samba/iX runtime configuration file.
TESTPARM	A program to test the Samba/iX configuration file.
TESTPRNS	A program to test server access to printers.

The Samba/iX product contains:

SMBD: This is the server that can provide most SMB services.
The SMB protocol section in the Samba/iX configuration file "SMB.CONF", describes the role of SMB. The HP 3000 running SMBD will act as a File and Print server for the clients using the SMB protocol. This is compatible with the LanManager protocol, and can service LanManager clients.
These clients include Windows for Workgroups, Windows 95 and Windows NT.
A session is created whenever a client requests one. Each client gets a child process for each session. This copy then services all connections made by the client during that session. When all connections from its client are closed, the copy of the server for that client terminates.
NMBD: This is a server that understands and can reply to NetBIOS Name Service Requests on TCP port 137, like those sent by LanManager clients.
NMBD also controls browsing (viewing the resources available on a Windows network is called browsing). When they start up, LanManager compatible clients such as Windows 95/Windows NT, may wish to locate a LanManager server. That is, they wish to know what IP address a specified host is using.
This program simply listens for such requests, and if its own name is specified, it will respond with the IP address of the host on which it is running. Its "own name" is by default the name of the host on which it is running.
SMBCLIENT: The SMBCLIENT is a client that can "talk" to an SMB server.
When this program is run on the HP 3000, it will be acting as a client. It is a command line program and offers an interface similar to that of the FTP program. Operations include things like "getting" files from the server to the local machine, "putting" files from the local machine to the server, retrieving directory information from the server, etc.
SMB.CONF: The SMB.CONF file is a configuration file of the Samba/iX suite which contains runtime configuration information for both SMBD and NMBD.
This file consists of sections and parameters. Each section in the configuration file corresponds to a service. The special sections are [global], [homes] and [printers]. The [global] section is used to set global configuration options that apply to the server as a whole. The [homes] section is designed to grant access to all users home directories and the entries in [printers] section correspond to the print services of the Samba/iX server.
TESTPARM: This is a test program to validate the contents of the SMB.CONF configuration file.
If this program reports no problems, you can use the configuration file with confidence that SMBD will successfully load the configuration file.

TESTPRNS: This tool checks whether the printer name is valid for the services provided by SMBD.

SMB Protocol

SMB, which stands for Server Message Block, is a protocol for sharing files, printers, serial ports, and communication abstractions, such as named pipes and mail slots, between computers.

SMB is a request/response protocol and it is implemented on top of the NetBIOS API, see Figure 7-2 "SMB Protocol". It plays the role of session, presentation, and a part of application layer of the OSI stack. SMB can be used over TCP/IP, NetBEUI, and IPX/SPX. In the case of TCP/IP or NetBEUI, the NetBIOS API is being used. Samba/iX uses SMB over TCP/IP.

Figure 7-2 SMB Protocol

The SMB messages can be categorized into four types of messages: session control, file, printer, and message. Session control messages start, authenticate, and terminate sessions. File command controls file access and printer command controls printer access. Message commands allow an application to send messages to or receive messages from another host. (For example, WinPopup messages). NetBIOS names are up to 15 characters long, and are usually the name of the computer that is running NetBIOS.

Example of SMB Conversation

Figure 7-3 "SMB NegProt Connection" demonstrates the process of connecting to a file space service. The SMB Negotiate Protocol command (NegProt) is used to decide on a protocol extension to be used with the server. The client sends a SMB NegProt to the server. This will list the protocol dialects/protocol extensions that it understands. The server responds with the index of the dialect that it wants to use, or 0xFFFF if none of the dialects were acceptable.Dialects newer than the Core and CorePlus protocols supply information in the NegProt response to indicate their capabilities such as max buffer size. The six important protocol extensions of SMB are Core, CorePlus, LAN Manager 1.0, LM 2.0, and NT LM 0.12 and CIFS 1.0.

Figure 7-3 SMB NegProt Connection

Once a protocol has been established, the client can proceed to logon to the server. Client now sends a SMB Session Setup command (SesssetupX), see Figure 7-4 "SMB Sesssetup Connection". The response indicates whether the username password pair is valid, and if so, can provide additional information. One of the very important aspects of the response is a User ID value that must be submitted with all the subsequent SMBs sent to the server. This is used for user authentication.

Figure 7-4 SMB Sesssetup Connection

After the client has logged in, then proceeds to connect to the file tree by sending a SMB Tree Connect command (TconX) to the server, see Figure 7-5 "SMB TconX Connection". Here TconX stands for tree connect. The client sends a Tcon or SMB TconX specifying the network name of the share that they wish to connect to, and if all is well, the server responds with a TID that the client will use in all future SMBs relating to that share.

Figure 7-5 SMB TconX Connection

After connecting to a tree, the client can now open a file with an open SMB, followed by reading it with read SMBs, writing it with write SMBs, and closing it with close SMBs.

Chapter 7 Samba/iX Services

Samba/iX Configuration File Options