manage installed services in Linux.
Services in linux are programs or called daemon's that once
started run continuously in the background and are ready for input or monitor
changes in your computer and respond to them. For example the Apache server has
a daemon called httpd ( The d is for daemon ) that listens on port 80 your
computer and when it receives a request for a page it sends the appropriate
data back to the client machine.
Many services are required to run all the time
however many can be safely turned of for both security reasons as running
unnecessary services opens more doors into your computer, but also for
performance reasons. It may not make much difference but your computer should
boot slightly faster with less services it has to start on boot.
One of the techniques in every Linux administrators
toolbox to improve security of a box is to turn off unneeded services.
Chkconfig
and service Commands
There
are 2 commands used to control services:
- Service – This controls the starting and stopping of services during a session, these setting are not saved. If you start Apache this way but it is not set to start on boot using the above method then it will continue to run but on next boot will not start automatically.
- Chkconfig – This controls which services are set to start on boot, by their nature these setting are saved and are applied at next boot. Changing these settings will not start the services immediately; it will just flag them to be strated from the next boot.
The
command use for maintaining a service is
#service
<name of the service> Status --- To
check the status of the service
#service
<name of the service> start --- To
start the service
#service
<name of the service> stop --- To stop
a service
#service
<name of the service> reload --- To
reload the service
#service
<name of the service> restart --- To
restart the service
#service
- - status-all --- To see all the service status
To
command use for service availability is
#chkconfig
– list --- To check the availability of service
#chkconfig
<service> on --- To make the service available after
restart
#chkconfig
<service> off --- To
make the service unavailable after restart
Now we will see how to use the above commands:
Check
the status of ftp service “vsftpd”
To check the status of the above service
#service
vsftpd status
|
[root@linuxelearn
Desktop]# service vsftpd status
vsftpd
is stopped
[root@linuxelearn
Desktop]#
|
Start
Ftp services
To start the ftp service, the command is
#service
vsftpd start
|
[root@linuxelearn
Desktop]# service vsftpd start
Starting
vsftpd for vsftpd: [ OK ]
[root@linuxelearn
Desktop]# service vsftpd status
vsftpd
(pid 3261) is running...
[root@linuxelearn
Desktop]#
|
Reload
the ftp services, may be required after doing some change in config file.
To reload the service, the command is
#service
vsftpd reload
|
[root@linuxelearn
Desktop]# service vsftpd reload
Shutting
down vsftpd: [ OK ]
Starting
vsftpd for vsftpd: [ OK ]
[root@linuxelearn
Desktop]#
|
To
restart the ftp or any service, required when reload does not work
To restart the ftp services, the command will be
#service
vsftpd restart
|
[root@linuxelearn
Desktop]# service vsftpd restart
Shutting
down vsftpd: [ OK ]
Starting
vsftpd for vsftpd: [ OK ]
[root@linuxelearn
Desktop]#
|
Check
the status of the all service availability using chkconfig command.
To check the status of all service availability, use
#chkconfig
–list
|
[root@linuxelearn
Desktop]# chkconfig --list
NetworkManager
0:off 1:off 2:on 3:on 4:on 5:on 6:off
abrtd 0:off 1:off 2:off 3:on 4:off 5:on 6:off
acpid 0:off 1:off 2:on 3:on 4:on 5:on 6:off
atd 0:off 1:off 2:off 3:on 4:on 5:on 6:off
auditd 0:off 1:off 2:on 3:on 4:on 5:on 6:off
autofs 0:off 1:off 2:off 3:on 4:on 5:on 6:off
avahi-daemon 0:off 1:off 2:off 3:on 4:on 5:on 6:off
bluetooth
0:off 1:off 2:off 3:on 4:on 5:on 6:off
certmonger 0:off 1:off 2:off 3:off 4:off 5:off 6:off
cgconfig 0:off 1:off 2:off 3:off 4:off 5:off 6:off
cgred 0:off 1:off 2:off 3:off 4:off 5:off 6:off
cpuspeed 0:off 1:on 2:on 3:on 4:on 5:on 6:off
crond 0:off 1:off 2:on 3:on 4:on 5:on 6:off
cups 0:off 1:off 2:on 3:on 4:on 5:on 6:off
dnsmasq 0:off 1:off 2:off 3:off 4:off 5:off 6:off
firstboot 0:off 1:off 2:off 3:off 4:off 5:off 6:off
haldaemon 0:off 1:off 2:off 3:on 4:on 5:on 6:off
httpd 0:off 1:off 2:off 3:off 4:off 5:off 6:off
ip6tables 0:off 1:off 2:on 3:on 4:on 5:on 6:off
iptables 0:off 1:off 2:on 3:on 4:on 5:on 6:off
irqbalance 0:off 1:off 2:off 3:on 4:on 5:on 6:off
kdump 0:off 1:off 2:off 3:off 4:off 5:off 6:off
lvm2-monitor 0:off 1:on 2:on 3:on 4:on 5:on 6:off
mdmonitor 0:off 1:off 2:on 3:on 4:on 5:on 6:off
messagebus 0:off 1:off 2:on 3:on 4:on 5:on 6:off
microcode_ctl 0:off 1:off 2:on 3:on 4:on 5:on 6:off
nagios 0:off 1:off 2:on 3:on 4:on 5:on 6:off
netconsole 0:off 1:off 2:off 3:off 4:off 5:off 6:off
netfs 0:off 1:off 2:off 3:on 4:on 5:on 6:off
network 0:off 1:off 2:on 3:on 4:on 5:on 6:off
nfs 0:off 1:off 2:off 3:off 4:off 5:off 6:off
nfslock 0:off 1:off 2:off 3:on 4:on 5:on 6:off
nscd 0:off 1:off 2:off 3:off 4:off 5:off 6:off
nslcd 0:off 1:off 2:off 3:off 4:off 5:off 6:off
ntpd 0:off 1:off 2:off 3:off 4:off 5:off 6:off
ntpdate 0:off 1:off 2:off 3:off 4:off 5:off 6:off
oddjobd 0:off 1:off 2:off 3:off 4:off 5:off 6:off
portreserve 0:off 1:off 2:on 3:on 4:on 5:on 6:off
postfix 0:off 1:off 2:on 3:on 4:on 5:on 6:off
psacct 0:off 1:off 2:off 3:off 4:off 5:off 6:off
rdisc 0:off 1:off 2:off 3:off 4:off 5:off 6:off
restorecond 0:off 1:off 2:off 3:off 4:off 5:off 6:off
rhnsd 0:off 1:off 2:on 3:on 4:on 5:on 6:off
rpcbind 0:off 1:off 2:on 3:on 4:on 5:on 6:off
rpcgssd 0:off 1:off 2:off 3:on 4:on 5:on 6:off
rpcidmapd 0:off 1:off 2:off 3:on 4:on 5:on 6:off
rpcsvcgssd 0:off 1:off 2:off 3:off 4:off 5:off 6:off
rsyslog 0:off 1:off 2:on 3:on 4:on 5:on 6:off
saslauthd 0:off 1:off 2:off 3:off 4:off 5:off 6:off
smartd 0:off 1:off 2:off 3:off 4:off 5:off 6:off
snmpd 0:off 1:off 2:off 3:off 4:off 5:off 6:off
snmptrapd 0:off 1:off 2:off 3:off 4:off 5:off 6:off
sshd 0:off 1:off 2:on 3:on 4:on 5:on 6:off
sssd 0:off 1:off 2:off 3:off 4:off 5:off 6:off
sysstat 0:off 1:on 2:on 3:on 4:on 5:on 6:off
udev-post 0:off 1:on 2:on 3:on 4:on 5:on 6:off
vsftpd 0:off 1:off 2:off 3:off 4:off 5:off 6:off
wpa_supplicant
0:off 1:off 2:off 3:off 4:off 5:off 6:off
ypbind 0:off 1:off 2:off 3:off 4:off 5:off 6:off
[root@linuxelearn
Desktop]#
|
Note:
where 0 1 2 3 4 5 6 are the run
levels in Linux, The output shows that on which run level the service is
available even after reboot.
Check
the status of a particular service, say “vsftpd”
To check the status of a vsftpd service, the command
is
#chkconfig
–list <name of the service>
#chkconfig
–list vsftpd
|
[root@linuxelearn
Desktop]# chkconfig --list vsftpd
vsftpd 0:off 1:off 2:off 3:off 4:off 5:off 6:off
[root@linuxelearn
Desktop]#
|
Make
the service availability on for vsftpd.
To make the service availability on for vsftpd
service,
#chkconfig
vsftpd on
|
[root@linuxelearn
Desktop]# chkconfig vsftpd on
[root@linuxelearn
Desktop]# chkconfig --list vsftpd
vsftpd 0:off 1:off 2:on 3:on 4:on 5:on 6:off
[root@linuxelearn
Desktop]#
|
Make
the service availability off for vsftpd
To make the service availability off the command is
#chkconfig
vsftpd off
|
[root@linuxelearn
Desktop]# chkconfig vsftpd off
[root@linuxelearn
Desktop]# chkconfig --list vsftpd
vsftpd 0:off 1:off 2:off 3:off 4:off 5:off 6:off
[root@linuxelearn
Desktop]#
|
Make
the service vsftpd availability on only runlevel 5
To make the service availability on, on a particular
runlevel, the syntax is
#chkconfig
–level <1-6> <service> <on/off>
#chkconfig
– level 5 vsftpd on
|
[root@linuxelearn
Desktop]# chkconfig --level 5 vsftpd on
[root@linuxelearn
Desktop]# chkconfig --list vsftpd
vsftpd 0:off 1:off 2:off 3:off 4:off 5:on 6:off
[root@linuxelearn
Desktop]#
|
The same can be done for making service unavailable
in a particular run level.
I hope you enjoyed reading this article….
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