THE LINUX STUFF: March 2018

Tuesday, 27 March 2018

Issues: the semaphore value occupied more than the default value.

Error Log:

[root@sankar ~]# grep "A semaphore set has to be" /var/log/messages | head

Mar 18 03:05:27 xxx Server Administrator (Shared Library): Data Engine EventID: 0 A semaphore set has to be created but the system limit for the maximum number of semaphore sets has been exceeded

Mar 18 03:05:34 xxx Server Administrator (Shared Library): Data Engine EventID: 0 A semaphore set has to be created but the system limit for the maximum number of semaphore sets has been exceeded

Mar 18 03:05:34 xxxx Server Administrator (Shared Library): Data Engine EventID: 0 A semaphore set has to be created but the system limit for the maximum number of semaphore sets has been exceeded

[root@sankar ~]# ipcs -ls

------ Semaphore Limits --------

max number of arrays = 128 //default value

max semaphores per array = 250

max semaphores system wide = 32000

max ops per semop call = 32

semaphore max value = 32767

Currently occupied values are

[root@sankar ~]#ipcs -s |wc -l

131

So, we need to increase the 128 to some bigger value.

But in our case we’ve find multiple values occupied Nagios. Like as below

[[root@sankar ~]# ipcs -s

------ Semaphore Arrays --------

key semid owner perms nsems

0x000000a7 2359296 root 600 1

0x00000000 2719745 root 600 1

0x00000000 2752514 root 600 1

0x00000000 2785283 root 600 1

0x00000000 3047428 root 600 1

0x00000000 3014661 root 600 1

0x00000000 2883590 root 600 1

0x00000000 2916359 root 600 1

0x00000000 2949128 root 600 1

0x00000000 2981897 root 600 1

0x00000000 3080202 root 600 1

0x00000000 3112971 root 600 1

0x00000000 3145740 root 600 1

0x00000000 3178509 root 600 1

0x00000000 3211278 root 600 1

0x00000000 3244047 root 600 1

0x00000000 3276816 root 600 1

0x00000000 3309585 root 600 1

0x00000000 3375122 root 600 1

0x00000000 3407891 root 600 1

0x00000000 3440660 root 666 1

0x00000000 3473429 root 600 1

0x00000000 3506198 root 600 1

0x00000000 1875542039 www 600 1

0x00000000 399966232 www 600 1

0x00000000 3866649 root 600 1

0x00000000 3899418 root 600 1

0x00000000 3932187 root 600 1

0x00000000 1065222172 www 600 1

0x00000000 1734672413 www 600 1

0x00000000 268402718 www 600 1

0x00000000 991526943 www 600 1

0x00000000 1003716640 www 600 1

0x00000000 214138913 www 600 1

0x00000000 893124642 www 600 1

0x00000000 12419107 root 600 1

0x00000000 12451876 root 600 1

0x00000000 12484645 root 600 1

0x00000000 12517414 root 600 1

0x00000000 12550183 root 600 1

0x00000000 12582952 root 600 1

0x00000000 12615721 root 600 1

0x00000000 12648490 root 600 1

0x00000000 893157419 www 600 1

0x00000000 892960812 www 600 1

0x00000000 1351516205 www 600 1

0x00000000 1351548974 www 600 1

0x00000000 1351581743 www 600 1

0x00000000 1351614512 www 600 1

0x00000000 1378058289 nagios 600 1

0x00000000 1378091058 nagios 600 1

0x00000000 1378123827 nagios 600 1

0x00000000 1378156596 nagios 600 1

0x00000000 1396604981 nagios 600 1

0x00000000 1396637750 nagios 600 1

0x00000000 1396670519 nagios 600 1

0x00000000 1396703288 nagios 600 1

0x00000000 1401192505 nagios 600 1

0x00000000 1401225274 nagios 600 1

0x00000000 1401258043 nagios 600 1

0x00000000 1401290812 nagios 600 1

0x00000000 1405780029 nagios 600 1

0x00000000 1405812798 nagios 600 1

0x00000000 1405845567 nagios 600 1

0x00000000 1405878336 nagios 600 1

0x00000000 1408041025 nagios 600 1

0x00000000 1408073794 nagios 600 1

0x00000000 1408106563 nagios 600 1

0x00000000 1408139332 nagios 600 1

0x00000000 1410302021 nagios 600 1

0x00000000 1410334790 nagios 600 1

0x00000000 1410367559 nagios 600 1

0x00000000 1410400328 nagios 600 1

0x00000000 1421869129 nagios 600 1

0x00000000 1421901898 nagios 600 1

0x00000000 1421934667 nagios 600 1

0x00000000 1421967436 nagios 600 1

0x00000000 1449721933 nagios 600 1

0x00000000 1449754702 nagios 600 1

0x00000000 1449787471 nagios 600 1

0x00000000 1449820240 nagios 600 1

0x00000000 2029092945 nagios 600 1

0x00000000 2029125714 nagios 600 1

0x00000000 2029158483 nagios 600 1

0x00000000 993919060 www 600 1

0x00000000 2029191253 nagios 600 1

0x00000000 2045313110 nagios 600 1

0x00000000 2045345879 nagios 600 1

0x00000000 2045378648 nagios 600 1

0x00000000 2045411417 nagios 600 1

0x00000000 2047574106 nagios 600 1

0x00000000 2047606875 nagios 600 1

0x00000000 2047639644 nagios 600 1

0x00000000 2047672413 nagios 600 1

0x00000000 2049966174 nagios 600 1

0x00000000 2049998943 nagios 600 1

0x00000000 2052161632 nagios 600 1

0x00000000 2052194401 nagios 600 1

0x00000000 2052227170 nagios 600 1

0x00000000 2052259939 nagios 600 1

0x00000000 2054422628 nagios 600 1

0x00000000 2054455397 nagios 600 1

0x00000000 2054488166 nagios 600 1

0x00000000 2054520935 nagios 600 1

0x00000000 2056683624 nagios 600 1

0x00000000 2056716393 nagios 600 1

0x00000000 2056749162 nagios 600 1

0x00000000 2056781931 nagios 600 1

0x00000000 2105573484 nagios 600 1

0x00000000 2105606253 nagios 600 1

0x00000000 2105639022 nagios 600 1

0x00000000 2105671791 nagios 600 1

0x00000000 2107834480 nagios 600 1

0x00000000 2107867249 nagios 600 1

0x00000000 2107900018 nagios 600 1

0x00000000 2107932787 nagios 600 1

0x00000000 516325492 nagios 600 1

0x00000000 516358261 nagios 600 1

0x00000000 516391030 nagios 600 1

0x00000000 516423799 nagios 600 1

0x00000000 518586488 nagios 600 1

0x00000000 1003618425 www 600 1

0x00000000 518619258 nagios 600 1

0x00000000 518652027 nagios 600 1

0x00000000 518684796 nagios 600 1

0x00000000 520945789 nagios 600 1

0x00000000 520978558 nagios 600 1

[root@sankar ~]#

[root@sankar ~]# ipcs -s |grep nagios |wc -l

We’ve restart the service nagios-agent and Data Engine(omsa) services.

[root@sankar ~]# service xinetd stop
Stopping xinetd: [ OK ]

[root@sankar ~]# /etc/init.d/dataeng stop
Stopping Systems Management Data Engine:
Stopping dsm_sa_eventmgrd: [ OK ]
Stopping dsm_sa_datamgrd: [ OK ]
[root@sankar ~]# /etc/init.d/dsm_sa_ipmi stop
Stopping dsm_sa_ipmi drivers: [ OK ]
[root@sankar ~]#/etc/init.d/dsm_sa_ipmi start
Starting dsm_sa_ipmi drivers: [ OK ]
[root@sankar ~]# /etc/init.d/dataeng start
Starting Systems Management Data Engine:
Starting dsm_sa_datamgrd: [ OK ]
Starting dsm_sa_eventmgrd: [ OK ]
[root@sankar ~]# service xinetd status
xinetd is stopped
[root@sankar ~]#service xinetd start

Starting xinetd: [ OK ]

Now currently occupied semaphore values like as below and that value under the default threshold.

[root@sankar ~]## ipcs -s |wc -l

Now we did not get the above errors on /var/log/messages.

Upgrade Python from 2.6.x to 2.7.x on RHEL/CentOS 6

Downloading latest Python version:

[root@sankar ~]# cd /opt

[root@sankar ~]#pwd
/opt
[root@sankar ~]# wget http://www.python.org/ftp/python/2.7.8/Python-2.7.8.tar.xz
--2018-03-23 16:40:12-- http://www.python.org/ftp/python/2.7.8/Python-2.7.8.tar.xz
Resolving www.python.org... 151.101.116.223, 2a04:4e42:1c::223
Connecting to www.python.org|151.101.116.223|:80... connected.
HTTP request sent, awaiting response... 301 Moved Permanently
Location: https://www.python.org/ftp/python/2.7.8/Python-2.7.8.tar.xz [following]
--2018-03-23 16:40:12-- https://www.python.org/ftp/python/2.7.8/Python-2.7.8.tar.xz
Connecting to www.python.org|151.101.116.223|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 10525244 (10M) [application/octet-stream]
Saving to: â€œPython-2.7.8.tar.xzâ€

100%[=========================================================================================>] 10,525,244 --.-K/s in 0.1s

2018-03-23 16:40:12 (95.9 MB/s) - â€œPython-2.7.8.tar.xzâ€ saved [10525244/10525244]

[root@sankar ~]# ls -ltrh
total 24M
-rw-r--r-- 1 root root 9.8M May 11 2013 Python-2.7.5.tar.xz
-rw-r--r-- 1 root root 11M Jun 29 2014 Python-2.7.8.tar.xz
drwxr-xr-x 3 root root 4.0K Aug 24 2016 sun
drwxr-xr-x 4 root bin 4.0K Aug 24 2016 SYMCquiesce
-rw-r--r-- 1 root root 3.8M Mar 3 2017 xymon-4.3.28.tar.gz
drwxrwxr-x 16 500 nagios 4.0K Mar 3 2017 xymon-4.3.28
drwxr-xr-x 5 monitor ctsrvp 4.0K Mar 24 2017 monitor
drwx------ 7 ansible ctmemp 4.0K Aug 3 2017 ansible
drwxr-xr-x. 2 root root 4.0K Oct 3 13:05 rh
drwxr-xr-x 18 root root 4.0K Mar 20 03:46 Python-2.7.5
[root@sankar ~]#

[root@sankar ~]#tar -xvf Python-2.7.8.tar.xz
[root@sankar ~]#ls -ltrh
total 24M
-rw-r--r-- 1 root root 9.8M May 11 2013 Python-2.7.5.tar.xz
drwxr-xr-x 17 1000 1000 4.0K Jun 29 2014 Python-2.7.8
-rw-r--r-- 1 root root 11M Jun 29 2014 Python-2.7.8.tar.xz
drwxr-xr-x 3 root root 4.0K Aug 24 2016 sun
drwxr-xr-x 4 root bin 4.0K Aug 24 2016 SYMCquiesce
-rw-r--r-- 1 root root 3.8M Mar 3 2017 xymon-4.3.28.tar.gz
drwxrwxr-x 16 500 nagios 4.0K Mar 3 2017 xymon-4.3.28
drwxr-xr-x 5 monitor ctsrvp 4.0K Mar 24 2017 monitor
drwx------ 7 ansible ctmemp 4.0K Aug 3 2017 ansible
drwxr-xr-x. 2 root root 4.0K Oct 3 13:05 rh
drwxr-xr-x 18 root root 4.0K Mar 20 03:46 Python-2.7.5
[root@sankar ~]#

[root@sankar ~]# ./configure --prefix=/usr/local

[root@sankar ~]# make

[root@sankar ~]# make altinstall

[root@sankar ~]# python2.7 -V
Python 2.7.8
[root@sankar ~]# python2.7
Python 2.7.8 (default, Mar 23 2018, 17:50:22)
[GCC 4.4.7 20120313 (Red Hat 4.4.7-18)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> quit()

Now we need to create a alias from default python path to latest version

[root@sankar ~]#python -V

Python 2.6.6

[root@sankar ~]# vi ~/.bashrc

# .bashrc

# Source global definitions

if [ -f /etc/bashrc ]; then

. /etc/bashrc

# User specific aliases and functions

alias python=/usr/local/bin/python2.7

[root@sankar ~]#source ~/.bashrc

Now it's shows upgraded version only

[root@sankar ~]#python -V

Python 2.7.8

Tuesday, 6 March 2018

[Dell OMSA] Dell EMC OpenManage Version 9.0.1 installation on RHEL7

1. verify the Dell service tag on the server

# dmidecode -t system
# dmidecode 3.0
Getting SMBIOS data from sysfs.
SMBIOS 2.6 present.

Handle 0x0100, DMI type 1, 27 bytes
System Information
Manufacturer: Dell Inc.
Product Name: PowerEdge R610
Version: Not Specified
Serial Number: ******* eg:XG7TU1K
UUID: *******************
Wake-up Type: Power Switch
SKU Number: Not Specified
Family: Not Specified

Handle 0x0C00, DMI type 12, 5 bytes
System Configuration Options
Option 1: NVRAM_CLR: Clear user settable NVRAM areas and set defaults
Option 2: PWRD_EN: Close to enable password

Handle 0x2000, DMI type 32, 11 bytes
System Boot Information
Status: No errors detected

2. Based on the service tag you need to search on Dell site: http://www.dell.com/support/ and download the OpenManger.

3. I am using script for this setup.

[root@sankar-HP ~]#wget -q -O - http://linux.dell.com/repo/hardware/latest/bootstrap.cgi | bash

[root@sankar-HP ~]#yum install srvadmin-all

Note: for first time it's need a reboot.

4. check the port is up or not
[root@sankar-HP ~]#netstat -ntlup |grep 1311
tcp6 0 0 :::1311 :::* LISTEN 12135/dsm_om_connsv

5.Open browser on run the like host-name or IP: 1311 eg(https://192.168.1.1:1311)

How to Enable or Disable SELinux on CentOS/RHEL 7

1. Verify the current status:

[root@sankar-HP ~]# cat /etc/redhat-release
CentOS Linux release 7.4.1708 (Core)

[root@sankar-HP ~]# uname -a
Linux AT-LC-CHAMBERLIN 3.10.0-693.17.1.el7.x86_64 #1 SMP Thu Jan 25 20:13:58 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux

[root@sankar-HP ~]# sestatus
SELinux status: enabled
SELinuxfs mount: /sys/fs/selinux
SELinux root directory: /etc/selinux
Loaded policy name: targeted
Current mode: enforcing
Mode from config file: enforcing
Policy MLS status: enabled
Policy deny_unknown status: allowed
Max kernel policy version: 28

2. Open a selinux config file,
[root@sankar-HP ~]# vi /etc/sysconfig/selinux

# This file controls the state of SELinux on the system.
# SELINUX= can take one of these three values:
# enforcing - SELinux security policy is enforced.
# permissive - SELinux prints warnings instead of enforcing.
# disabled - No SELinux policy is loaded.
SELINUX=disabled
# SELINUXTYPE= can take one of three two values:
# targeted - Targeted processes are protected,
# minimum - Modification of targeted policy. Only selected processes are protected.
# mls - Multi Level Security protection.
SELINUXTYPE=targeted

[root@sankar-HP ~]#reboot
[root@sankar-HP ~]# sestatus
SELinux status: disabled

How to Start/Stop or Enable/Disable firewalld on CentOS/RHEL 7

[root@sankar-HP ~]# systemctl status firewalld
â— firewalld.service - firewalld - dynamic firewall daemon
Loaded: loaded (/usr/lib/systemd/system/firewalld.service; enabled; vendor preset: enabled)
Active: active (running) since Fri 2018-03-02 18:39:44 PST; 3 days ago
Docs: man:firewalld(1)
Main PID: 1001 (firewalld)
CGroup: /system.slice/firewalld.service
â””â”€1001 /usr/bin/python -Es /usr/sbin/firewalld --nofork --nopid

[root@sankar-HP ~]#systemctl disable firewalld
Removed symlink /etc/systemd/system/multi-user.target.wants/firewalld.service.
Removed symlink /etc/systemd/system/dbus-org.fedoraproject.FirewallD1.service.

[root@sankar-HP ~]# systemctl stop firewalld

[root@sankar-HP ~]#systemctl status firewalld
â— firewalld.service - firewalld - dynamic firewall daemon
Loaded: loaded (/usr/lib/systemd/system/firewalld.service; disabled; vendor preset: enabled)
Active: inactive (dead)
Docs: man:firewalld(1)

systemd[1]: Starting firewalld - dynamic firewall daemon...
systemd[1]: Started firewalld - dynamic firewall daemon.
firewalld[1001]: WARNING: ICMP type 'beyond-scope' is not supported by the kernel for ipv6.
firewalld[1001]: WARNING: beyond-scope: INVALID_ICMPTYPE: No supported ICMP type., ignoring for run-time.
.......
systemd[1]: Stopping firewalld - dynamic firewall daemon...
systemd[1]: Stopped firewalld - dynamic firewall daemon.