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SAMBA• Implements the ability for a Linux machine to
communicate with and act like a Windows file server.– Implements
• File sharing
• Printer sharing
• On Linux you run smbd. Configure the smb.conf file.
• In windows, your linux machine appears as a new machine in the Neighborhood Network.
SAMBA• For more information about SAMBA, or to find out
how to install/configure it.– http://www.samba.org
nfs• What if you have 2 UNIX machines who would like
to share files with each other.
• One is a server, the other is a client. – We’ll configure both.
Server – Start services• As root type:
rpc.mountd
rpc.nfsd
• To have these start automatically put them in startup files.
• If you make any changes to the /etc/exports file, you will need to run
exportfs
Client - /etc/fstab• Find out the IP address of your cousin.
• Make a new directory:mkdir /cousin
• Add the following to /etc/fstab
63.34.78.19:/usr /cousin nfs
• Now save that file and then type:
mount -a
Testing it out• Now on your machine, you should be able to see
your cousins /usr partition.
• As setup, this is a read only mount. To change this, you would use rw instead of ro in the /etc/exports file.
User accounts• One big job of a system administrator is managing
users.– Adding new users when employees are hired.– Deleting old ones are they are fired/quit.– Managing user groups– Resetting passwords
Create a new user.• Usually done with the adduser command.
– This simply does the following:• Adds a new line in /etc/passwd
• Creates a new directory for this person.
• Puts the default files into the new directory.
• Changes ownership and permissions of the files for the user.
Groups• User groups are defined in /etc/group
• prof:x:101:chastine,delgado,booth,coleman,wilson,tomas,preston,enda
• Users can be members of multiple groups
• To see what groups you are a member of use:– id
Changing passwords• Users can change their password at any time.
– passwd• Asks for old password, and then new password twice.
• If a user forgets their password, there is no way to find it out.– Root user can run
• passwd enda
• This will allow him to set a new password for enda, without knowing the old one.
Setting up directory.• /etc/skel
• This is a skeleton directory which has the basic files which a user would need.– .bash_profile etc.
• To manually setup a user:– mkdir /home/enda– cp –R /etc/skel /home/enda– chown –R enda:enda /home/enda– chmod –R 744 /home/enda
Disable a user• Usually done by either:
– Change their shell to /bin/false– Or delete them from /etc/passwd
– You can also user• userdel enda
Logging• A log file is a great resource for finding out what is
going on.– Main logfile is located in /var/log
• /var/log/messages
– Additional logs may exist in there for various applications:
• Web Server logs
• FTP Server logs
• Mail logs
syslogd• Runs all the time in the background as a deamon.• Reads configuration file /etc/syslog.conf
– This determines how various levels of errors or messages are handled.
• Broken up as follows:– kern.* /dev/console– daemon.warning /var/log/messages
• These would mean:– Any message from the kernel should be written to
console– Warning messages from daemons should be written to
/var/log/messages.
Levels of messages• Debug
– You probably never care• Info
– General startup, shutdown of program.• Notice
– User enda logged out etc.• Warnings
– Non critical problems• err
– Errors from the program.• Crit
– Critical errors which may cause the program to crash• alert
– Critical errors, which may effect other things• emerg
– Wow…the system could crash because of this.
Who can log• Messages usually come from:
– daemon– kern– auth– cron– mail– local0-7– Actual program names.
After changes - HUP• Once you make changes to syslog.conf. You must
tell syslogd to reread its configuration file.– kill –HUP [process ID of syslogd]
logger• If you want to log something in the log file, you can
use logger.– Useful in a script which may be run in background as
daemon, or as a cron job.• logger Test
– If you want it to log under a certain priority:• logger –p daemon.info “Started up”
logrotate• The program logrotate can be used to rotate your
logfiles.– By default on a RedHat system, logfiles are rotated every
week, and the previous 4 are kept.• With this weeks logfile, you have approx 5 weeks of logfiles.
– Configured in:• /etc/logrotate.conf• If you have a very busy system, this may be too much.
• Nothing magical, crontab which does:– mv messages messages.old– touch /var/log/messages– kill –HUP syslogd