Linux File-Sharing Services

You can share files from a Linux computer in many ways. Generally, you configure a server and then share files through a directory. The four major types of Linux sharing servers are FTP, NFS, Samba, and Apache. If you ve enabled NIS, it also shares configuration files. While there are graphical configuration tools available for each of these services, they all can be set up from the command-line interface as well, and they each include regular text commands for the client and server. For detailed information on these services, see Chapters 27 30 .

FTP Servers

The basic FTP commands are covered in detail in Chapter 27 . This section summarizes associated commands and configuration files.. While the Red Hat Linux 9 Installation CD now includes only vsFTP, WU-FTP is a popular option also available in RPM format. The vsFTP server comes highly recommended; Red Hat uses it on its own FTP servers.

vsFTP Commands and Configuration Files

The vsFTP package includes its own set of configuration files. It is simpler than alternative servers such as WU-FTP; the only command you need is the vsftpd daemon. The vsFTP server is now a regular service in the /etc/rc.d/init.d directory; it is no longer an xinetd service. If both servers are installed, be sure to activate only one at a time. The vsFTP configuration files are shown in Table A.29.

Table A.29: vsFTP Configuration Files

File

Description

/etc/vsftpd.conf

The primary configuration file.

/etc/vsftpd.ftpusers

A list of users not allowed to log in; should include service-level users such as news, bin, and mail, as well as root.

/etc/vsftpd.user_list

A list of allowed or denied users, depending on the userlist_deny variable in /etc/vsftpd.conf .

WU-FTP Commands and Configuration Files

One major alternative to vsFTP is WU-FTP, which you can download through the home page of their development group at www.wu- ftpd .org or the resource center at www.landfield.com/wu-ftpd/ . The commands shown in Table A.30 are available to help you manage a WU-FTP server. Remember, WU-FTP is an xinetd service that you also need to activate through the wu-ftpd file in the /etc/ xinted.d directory. Alternatively, you can use chkconfig to activate this service.

Table A.30: WU-FTP Commands

Command

Description

ckconfig

Checks the integrity of the configuration files.

ftpcount

Lists the number of connections.

ftpwho

Lists connected users and origin IP addresses.

ftprestart

Stops and restarts an FTP server.

ftpshut

Allows you to shut down an FTP server now or at a specified time.

in.ftpd

Starts the FTP server daemon.

in.wuftpd

Starts the WU-FTP server.

privatepw

Adds and deletes FTP groups from /etc/ftpgroups; these groups need to correspond to a real group in /etc/group .

The WU-FTP server also has a group of configuration files, as shown in Table A.31. You might recall from Chapter 27 that the functionality of some of these files is now part of /etc/ftpaccess .

Table A.31: WU-FTP Configuration Files

File

Functionality

/etc/ftpaccess

Opens the basic WU-FTP configuration file.

/etc/ftpconversions

Lists commands that are run automatically during FTP uploads or downloads.

/etc/ftpgroups

Defines special groups with a specific password, defined through the privatepw command.

/etc/ftphosts

Allows or denies access to a specific user account.

/etc/ftpusers

Allows or denies access to specific users.

FTP Client

There are a number of FTP clients available; all that I ve seen are front-ends to the FTP text client. The list of available FTP client commands is quite varied. The more important commands were addressed in Chapter 27 . A fuller list follows in Table A.32. This is just a basic list, without options. You can get more information from the ftp > prompt by entering help command .

Table A.32: FTP Client Commands

Command

Description

!

Escapes to the shell; the !ls -l command gives you a full list of files in the current local directory.

$

Executes a macro.

append

Appends a file to another file; e.g., the append local remote command adds the contents of the local file to the remote file.

ascii

Sets file transfer to ASCII mode.

bell

Toggles a beep when a command, such as a file transfer, is complete.

binary

Sets file transfer to binary mode.

bye

Exits the current FTP session.

cd

Changes the directory.

cdup

Moves up one directory level.

close

Closes the connection without exiting FTP.

delete

Deletes the specified file on a remote directory.

dir

Equivalent to ls “l .

exit

Closes connection and exits FTP.

get

Copies a file from the FTP server.

hash

Toggles the use of hash marks, so you can monitor the progress of a file transfer.

lcd

Changes the working directory on the local computer.

ls

Equivalent to ls -l in the bash shell.

mdelete

Deletes multiple files.

mdir

Takes the contents of a remote directory and outputs them to a local file.

mget

Copies multiple files from the FTP server.

mkdir

Creates a new directory on the FTP server.

mput

Sends multiple files to the FTP server.

newer

Uses the get command if the remote file is newer.

open

From the FTP prompt, connects to a remote FTP server.

put

Copies a file to the FTP server.

pwd

Lists the working directory on the FTP server.

quit

Exits the FTP shell.

rename

Renames a file on the FTP server.

rmdir

Removes a remote directory.

status

Checks the status of the connection.

system

Shows the basic system type, usually Unix.

user

Logs in as a user.

NFS Commands

The Network File System (NFS) is used to share directories between Linux and Unix computers. The basic configuration process is described in detail in Chapter 28 ; Table A.33 summarizes some important commands.

Table A.33: NFS Commands

Command

Description

exportfs

Exports and maintains the list of available NFS directories, based on /etc/exports .

nfsstat

Returns information on shared NFS directories; the output from this command is a good place to look for connection problems.

nhfsstone

Tests the load on an NFS server.

rpc. mountd

Starts the NFS mount daemon, the service that actually checks mount requests against what s allowed in /etc/exports .

nhfsrun

Tests program; runs nhfsstone with a range of demands on the server.

showmount

Shows available directories from an NFS server.

NIS Commands

The Network Information System (NIS) allows you to set up a single database of key configuration files such as /etc/passwd in a LAN of Linux and Unix computers. The basic configuration process is described in detail in Chapter 28 ; the important commands are summarized in Table A.34. Many key NIS commands are in an unusual directory, /usr/lib/yp . If you use NIS, you might consider adding that directory to your PATH with the PATH=$PATH:/usr/lib/yp command.

Table A.34: NIS Commands

Command

Description

create_printcap

Processes an LPD file such as /etc/printcap to an NIS database map; does not process a CUPS printer configuration file.

makedbm

Creates an NIS database file.

match_printcap

Works with the printcap_path in /etc/lpd.conf; does not process a CUPS printer configuration file.

mknetid

Generates an NIS database map from key configuration files: /etc/passwd , /etc/group , and /etc/ hosts .

pwupdate

Updates the NIS database map for regular and shadow passwords.

revnetgroup

Generates reverse NIS netgroup data.

ypcat

Reads files from an NIS server database.

ypchfn

Changes a user s finger information in the NIS database.

ypchsh

Changes a user s default shell in the NIS database.

ypinit

Builds a database for a master or slave NIS server.

ypmatch

Searches for a user in the NIS database.

yppasswd

Changes a password in the NIS database.

yppush

Replicates an NIS master database to an NIS slave server.

ypxfr

Copies an NIS database; common for NIS slave servers.

Samba Commands

Samba lets you configure Linux to connect and share directories with Microsoft Windows computers. Linux and Unix computers can also use Samba to share directories with each other.

As discussed in Chapter 29 , you could use the SWAT utility to configure Samba. SWAT is certainly a rich and detailed tool. But remember, like other GUI tools, it is just a front end to a group of commands. There are a substantial number of Samba commands ”some related to the server, others used commonly by Samba clients.

Samba Server Commands

When you configure a Samba server, you re sharing directories and printers in a format compatible with Microsoft Windows. Important Samba server commands are shown in Table A.35.

Table A.35: Samba Server Commands

Command

Description

make_unicodemap

Specifies a translation ”from DOS or Unix text to 16-bit Unicode.

mksmbpasswd.sh

Starts a script that directly edits the SMB password file, /etc/samba/smbpasswd .

smbadduser

Sets up a database entry between a Linux user and a Microsoft Windows user; prompts for a password and enters the result in /etc/ smbusers and /etc/smbpasswd .

smbcontrol

Allows you to send messages to an SMB server, such as debug, elections , and ping messages.

smbpasswd

Changes a user s Samba password; can apply to local or remote Samba servers.

smbstatus

Displays the status of connections to the local SMB server.

testparm

Checks the syntax of smb.conf .

testprns

Checks a proposed Samba share name for a printer.

winbindd

Starts the name service daemon for Microsoft Windows “style server names .

Samba Client Commands

When you configure a Samba client, you re using commands on a Linux or Unix computer to connect to a shared Samba or Microsoft Windows directory. Important Samba client commands are shown in Table A.36.

Table A.36: Samba Client Commands

Command

Description

mount.smb

Allows you to use the mount command as a front end to connect to a shared Samba directory.

nmblookup

Searches for the IP address associated with a NetBIOS name.

rpcclient

Permits connections to remote procedure calls on a Microsoft Windows server.

smbcacls

Allows you to view and set the Access Control List on a Microsoft Windows server.

smbclient

Lets you connect directly to a Samba server, with an FTP-style interface.

smbmount

Mounts a Samba filesystem; you can use the mount command as a front end to this command.

smbprint

Sends a print job to a shared printer on a Samba server.

smbumount

Unmounts a shared Samba directory.

Apache Commands

Apache is the most popular web server on the Internet, as well as the default web server for Red Hat Linux. As discussed in Chapter 30 , the standard way to configure Apache is by editing the /etc/httpd/conf/httpd.conf configuration file. Commands are available to help you work with whatever Apache configuration you use. Some of the more important ones are listed in Table A.37.

Table A.37: Apache Commands

Command

Description

ab

A tool for testing the performance of your Apache server.

apachectl

A control script for your Apache server.

htdbm

A new Apache 2.0 tool for managing authorized user/password databases.

htdigest

A tool that creates an authentication database of users and passwords.

htpasswd

A tool that allows you to set up individual users and passwords for your web server.

httpd

The Apache daemon; httpd -t tests the syntax of your httpd.conf configuration file.

logresolve

A tool that performs a reverse name lookup for Apache log files, so you know the computers or domains that are connecting to your server.

rotatelogs

A tool that rotates Apache log files automatically; otherwise , to use the standard logrotate job, which is governed by cron , you d have to stop the Apache server.

 


Mastering Red Hat Linux 9
Building Tablet PC Applications (Pro-Developer)
ISBN: 078214179X
EAN: 2147483647
Year: 2005
Pages: 220

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