How
to Stop and Disable Unwanted Services from Linux System
When building a server we need to ask ourselves what we actually
need from the box. Do I need a Web Server or
a FTP Server, a NFS Server or
a DNS Server, a Database Server or
something else.
Here in this article, we will be discussing some of these
unwanted applications and services which you might not needed but they are
installed by default during OS installation and unknowingly start eating your
system resources.
Lets first know what kind of services are running on the system
using the following commands.
[avishek@tecmint]# ps ax
Sample Output
PID TTY STAT TIME COMMAND
2 ? S 0:00 [kthreadd]
3 ? S 0:00 \_ [migration/0]
4 ? S 0:09 \_ [ksoftirqd/0]
5 ? S 0:00 \_ [migration/0]
6 ? S 0:24 \_ [watchdog/0]
7 ? S 2:20 \_ [events/0]
8 ? S 0:00 \_ [cgroup]
9 ? S 0:00 \_ [khelper]
10 ? S 0:00 \_ [netns]
11 ? S 0:00 \_ [async/mgr]
12 ? S 0:00 \_ [pm]
13 ? S 0:16 \_ [sync_supers]
14 ? S 0:15 \_ [bdi-default]
15 ? S 0:00 \_ [kintegrityd/0]
16 ? S 0:49 \_ [kblockd/0]
17 ? S 0:00 \_ [kacpid]
18 ? S 0:00 \_ [kacpi_notify]
19 ? S 0:00 \_ [kacpi_hotplug]
20 ? S 0:00 \_ [ata_aux]
21 ? S 58:46 \_ [ata_sff/0]
22 ? S 0:00 \_ [ksuspend_usbd]
23 ? S 0:00 \_ [khubd]
24 ? S 0:00 \_ [kseriod]
.....
Now, let’s have a quick look at the processes accepting
connection (ports) using the netstat command as shown below.
[avishek@tecmint]# netstat -lp
Sample Output
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 *:31138 *:* LISTEN 1485/rpc.statd
tcp 0 0 *:mysql *:* LISTEN 1882/mysqld
tcp 0 0 *:sunrpc *:* LISTEN 1276/rpcbind
tcp 0 0 *:ndmp *:* LISTEN 2375/perl
tcp 0 0 *:webcache *:* LISTEN 2312/monitorix-http
tcp 0 0 *:ftp *:* LISTEN 2174/vsftpd
tcp 0 0 *:ssh *:* LISTEN 1623/sshd
tcp 0 0 localhost:ipp *:* LISTEN 1511/cupsd
tcp 0 0 localhost:smtp *:* LISTEN 2189/sendmail
tcp 0 0 *:cbt *:* LISTEN 2243/java
tcp 0 0 *:websm *:* LISTEN 2243/java
tcp 0 0 *:nrpe *:* LISTEN 1631/xinetd
tcp 0 0 *:xmltec-xmlmail *:* LISTEN 2243/java
tcp 0 0 *:xmpp-client *:* LISTEN 2243/java
tcp 0 0 *:hpvirtgrp *:* LISTEN 2243/java
tcp 0 0 *:5229 *:* LISTEN 2243/java
tcp 0 0 *:sunrpc *:* LISTEN 1276/rpcbind
tcp 0 0 *:http *:* LISTEN 6439/httpd
tcp 0 0 *:oracleas-https *:* LISTEN 2243/java
....
In the above output, you notice that some of the applications
you may not needed on your server but they are still running as follows:
1. smbd and nmbd
smbd and nmbd are daemon of Samba Process. Do you really need to
export smb share on windows or other machine. If not! why are these processes
running? You can safely kill these processes and disable them from starting
automatically when machine boots the next time.
2. Telnet
Do You need bidirectional interactive text-oriented
communication over internet or local area network? If not! kill this process
and turn-off it from starting at booting.
3. rlogin
Do you need to log in to another host over network. If not! Kill
this process and disable it from starting automatically at boot.
4. rexec
The Remote Process Execution aka rexec lets you execute shell
commands on a remote computer. If you don’t require to execute shell command on
a remote machine, simply kill the process.
5. FTP
Do you need to transfer files from one host to another host over
Internet? If not you can safely stop the service.
6. automount
Do you need to mount different file systems automatically to
bring up network file system? If not! Why is this process running? Why are you
letting this application to use you resource? Kill the process and disable it
from starting automatically.
7. named
Do you need to run NameServer (DNS)? If not what on earth is
compelling you to run this process and allow eating up your resources. Kill the
running process first and then turn-off it from running it at boot.
8. lpd
lpd is the printer daemon which makes it possible to print to
that server. If you don’t need to print from the server chances are your system
resources are being eaten up.
9. Inetd
Are you running any inetd services? If you are running stand
alone application like ssh which uses other stand alone application like Mysql,
Apache, etc. then you don’t need inetd. better kill the process and disable it
starting next time automatically.
10. portmap
Portmap which is an Open Network Computing Remote Procedure Call
(ONC RPC) and usages daemon rpc.portmap and rpcbind. If these Processes are
running, means you are running NFS server. If NFS server is running unnoticed
means your system resources are being used up un-necessarily.
How to Kill a
Process in Linux
In order to kill a running process in Linux, use the ‘Kill PID‘ command. But, before running Kill
command, we must know the PID of
the process. For example, here I want to find a PID of ‘cupsd‘ process.
[avishek@tecmint]# ps ax | grep cupsd
1511 ? Ss 0:00 cupsd -C /etc/cups/cupsd.conf
So, the PID of ‘cupsd‘
process is ‘1511‘. To kill
that PID, run the following command.
[avishek@tecmint]# kill -9 1511
How to Disable a Services
in Linux
In Red Hat based
distributions such as Fedora and CentOS, make use of a script called ‘chkconfig‘ to enable and disable the running
services in Linux.
For example, lets disable the Apache web server at the system
startup.
[avishek@tecmint]# chkconfig httpd off
[avishek@tecmint]# chkconfig httpd --del
In Debian based
distributions such as Ubuntu, Linux Mint and
other Debian based distributions use a script called update-rc.d.
For example, to disable the Apache service at the system startup
execute the following command. Here ‘-f’ option stands for force is mandatory.
[avishek@tecmint]# update-rc.d -f apache2 remove
After making these changes, The system next time will boot
without these UN-necessary process which in-fact will be saving our system
resource and the server would be more practical, fast, safe and secure.
Thank You
