COVID-19 Situation RedHat provides free courses for 30 Days duration

Because of COVID-19 Situation RedHat provides free courses for 30Days durations. Get the benifits as much as you can. These all are worth more than ₹10-₹15k at RedHat. Here, I’m attaching all the links of free courses.

Complimentary Technical Overviews:
Red Hat Enterprise Linux Technical Overview (RH024)https://www.redhat.com/en/services/training/rh024-red-hat-linux-technical-overview
Red Hat Agile Integration Technical Overview (DO040)https://www.redhat.com/en/services/training/do040-red-hat-agile-integration-technical-overview
Ansible Essentials: Simplicity in Automation Technical Overview (DO007)https://www.redhat.com/en/services/training/do007-ansible-essentials-simplicity-automation-technical-overview
Deploying Containerized Applications Tech Overview (DO080)https://www.redhat.com/en/services/training/do080-deploying-containerized-applications-technical-overview
Red Hat Satellite Technical Overview (RH053)https://www.redhat.com/en/services/training/rh053-red-hat-satellite-technical-overview
Red Hat OpenStack Technical Overview (CL010)https://www.redhat.com/en/services/training/cl010-red-hat-openstack-technical-overview
Virtualization and Infrastructure Migration Technical Overview (RH018)https://www.redhat.com/en/services/training/rh018-virtualization-and-infrastructure-migration-technical-overview

www.redhat.com

Install ARBT packages on RHEL/CentOS 7

You can download below packages from this mirror and install them via yum OR rpm command
http://mirror.centos.org/altarch/7/os/aarch64/Packages/

Command for e.g:-

  • wget http://mirror.centos.org/altarch/7/os/aarch64/Packages/abrt-2.1.11-55.el7.centos.aarch64.rpm
  • yum install abrt-2.1.11-55.el7.centos.aarch64.rpm OR rpm -ivh abrt-2.1.11-55.el7.centos.aarch64.rpm

abrt-2.1.11-55.el7.centos.aarch64.rpm
abrt-addon-ccpp-2.1.11-55.el7.centos.aarch64.rpm
abrt-addon-kerneloops-2.1.11-55.el7.centos.aarch64.rpm
abrt-addon-pstoreoops-2.1.11-55.el7.centos.aarch64.rpm
abrt-addon-python-2.1.11-55.el7.centos.aarch64.rpm
abrt-addon-upload-watch-2.1.11-55.el7.centos.aarch64.rpm
abrt-addon-vmcore-2.1.11-55.el7.centos.aarch64.rpm
abrt-addon-xorg-2.1.11-55.el7.centos.aarch64.rpm
abrt-cli-2.1.11-55.el7.centos.aarch64.rpm
abrt-console-notification-2.1.11-55.el7.centos.aarch64.rpm
abrt-dbus-2.1.11-55.el7.centos.aarch64.rpm
abrt-desktop-2.1.11-55.el7.centos.aarch64.rpm
abrt-devel-2.1.11-55.el7.centos.aarch64.rpm
abrt-gui-2.1.11-55.el7.centos.aarch64.rpm
abrt-gui-devel-2.1.11-55.el7.centos.aarch64.rpm
abrt-gui-libs-2.1.11-55.el7.centos.aarch64.rpm
abrt-java-connector-1.0.6-12.el7.aarch64.rpm
abrt-libs-2.1.11-55.el7.centos.aarch64.rpm
abrt-python-2.1.11-55.el7.centos.aarch64.rpm
abrt-python-doc-2.1.11-55.el7.centos.noarch.rpm
abrt-retrace-client-2.1.11-55.el7.centos.aarch64.rpm
abrt-tui-2.1.11-55.el7.centos.aarch64.rpm

Remove queued mails for particular Email account – Zimbra/Postfix

Login to the server via SSH and run below command:-

# /opt/zimbra/common/sbin/postqueue -p | tail -n +2 | awk 'BEGIN { RS = "" } /[email protected]\.com/ { print $1 }' | tr -d '*!' | /opt/zimbra/common/sbin/postsuper -d -
  • Replace navdeep.singh and domain name with your choice
  • You can also use above command on a non-zimbra server but make sure it has postfix for the mailing puprose, in this case you can just use postqueue and postsuper instead of using their full path.
  • Your zimbra server may has postqueue and postsuper in a bit different folder so try to find them and best way to do that is this:-
# updatedb         # make sure you has mlocate package OR locate command installed
# locate postqueue
# locate postsuper

 

Install OCS Inventory Agent on CentOS 7

  1. Install EPEL Repo on CentOS 7
    cd /tmp
    wget https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm
    yum install -y epel-release-latest-7.noarch.rpm
    yum --disablerepo="*" --enablerepo="epel" install ocsinventory-agent -y
  2. Install Basic packages for agent
    yum install perl-XML-Simple perl-Net-IP
  3. Download latest agent rpm package
    wget https://dl.fedoraproject.org/pub/epel/7/x86_64/Packages/o/ocsinventory-agent-2.6.0-3.2.el7.x86_64.rpm
  4. Install package
    yum install ocsinventory-agent-2.6.0-3.2.el7.x86_64.rpm
  5. Open the configuration file.
    vi /etc/ocsinventory/ocsinventory-agent.cfg
  6. Uncomment the following lines. Set a tag for the current server and the address of your OCS server.
    server = http://your.ocs.server/ocsinventory
    tag = your_tag
  7. Restart agent
    service ocsinventory-agent restart
  8. To force the sending of inventory execute the following
    /usr/sbin/ocsinventory-agent
  9. How to check if ocsinventory-agent is installed or not
    rpm -qa | grep ocsinventory-agent

Samba: Linux Iptables Firewall Configuration – Allow Samba ports in CentOS 6

Add below rules in iptables rule file
vi /etc/sysconfig/iptables

Rules:-

-A INPUT -s 0.0.0.0/0 -m state –state NEW -p udp –dport 137 -j ACCEPT
-A INPUT -s 0.0.0.0/0 -m state –state NEW -p udp –dport 138 -j ACCEPT
-A INPUT -s 0.0.0.0/0 -m state –state NEW -p tcp –dport 139 -j ACCEPT
-A INPUT -s 0.0.0.0/0 -m state –state NEW -p tcp –dport 445 -j ACCEPT

Now restart iptables service
service iptables restart

 

[Solved] Fatal error: Uncaught CredisException: Connection to Redis 127.0.0.1:6379 failed. Last Error : (111) Connection refused

Error:- Fatal error: Uncaught CredisException: Connection to Redis 127.0.0.1:6379 failed after 2 failures.Last Error : (111) Connection refused in /home/the-d2/public_html/vendor/colinmollenhour/credis/Client.php:463 Stack trace: #0 /home/the-d2/public_html/vendor/colinmollenhour/credis/Client.php(459): Credis_Client->connect() #1 /home/the-d2/public_html/vendor/colinmollenhour/credis/Client.php(792): Credis_Client->connect() #2 /home/the-d2/public_html/vendor/colinmollenhour/cache-backend-redis/Cm/Cache/Backend/Redis.php(432): Credis_Client->__call(‘hGet’, Array) #3 /home/the-d2/public_html/vendor/magento/zendframework1/library/Zend/Cache/Core.php(306): Cm_Cache_Backend_Redis->load(’33d_GLOBAL__DIC…’, false) #4 /home/the-d2/public_html/vendor/magento/framework/Cache/Frontend/Adapter/Zend.php(39): Zend_Cache_Core->load(’33d_GLOBAL__DIC…’) #5 /home/the-d2/public_html/vendor/magento/framework/Cache/Frontend/Decorator/Bare.php(65): Magento\Framework\Cache\Frontend\Adapter\Z in /home/the-d2/public_html/vendor/colinmollenhour/credis/Client.php on line 463

Solution:- Try restarting the redis service and flush redis cache.
# service redis restart
# redis-cli flushall

[Solved] certificate verification failed for untrusted issuer /OU=GlobalSign Root CA

Error:-

Nov 11 17:09:43 server postfix/smtp[30572]: certificate verification failed for aspmx.l.google.com[74.125.200.26]:25: untrusted issuer /OU=GlobalSign Root CA – R2/O=GlobalSign/CN=GlobalSign
Nov 11 17:14:31 server postfix/smtp[3332]: certificate verification failed for in.hes.trendmicro.com[54.219.191.21]:25: untrusted issuer /C=BE/O=GlobalSign nv-sa/OU=Root CA/CN=GlobalSign Root CA
Nov 11 17:19:32 server postfix/smtp[5333]: certificate verification failed for mx6.mail.icloud.com[17.133.229.15]:25: untrusted issuer /C=US/O=GeoTrust Inc./CN=GeoTrust Global CA
Nov 11 17:19:35 server postfix/smtp[5333]: certificate verification failed for mx5.mail.icloud.com[17.133.229.14]:25: untrusted issuer /C=US/O=GeoTrust Inc./CN=GeoTrust Global CA

Solution:-

You need to mention the SSL CA file path, For me it was letsencrypt SSL and i gave it the complete chain, It worked.
Added below line in /etc/postfix/main.cf and restarted postfix

smtp_tls_CAfile = /etc/letsencrypt/live/the-d2.com/fullchain.pem

service postfix restart

[Solved] Error getting authority: PolicyKit1′: timed out (g-dbus-error-quark, 20)

Error:-

Error getting authority: Error initializing authority: Error calling StartServiceByName for org.freedesktop.PolicyKit1: GDBus.Error:org.freedesktop.DBus.Error.TimedOut: Failed to activate service ‘org.freedesktop.PolicyKit1’: timed out (g-dbus-error-quark, 20)

Troubleshooting:-

systemctl status polkit
● polkit.service – Authorization Manager
Loaded: loaded (/usr/lib/systemd/system/polkit.service; static; vendor preset: enabled)
Active: failed (Result: exit-code) since Sat 2019-11-16 09:02:02 EST; 1min 58s ago
Docs: man:polkit(8)
Process: 11321 ExecStart=/usr/lib/polkit-1/polkitd –no-debug (code=exited, status=1/FAILURE)
Main PID: 11321 (code=exited, status=1/FAILURE)

systemctl start polkit
Error getting authority: Error initializing authority: Error calling StartServiceByName for org.freedesktop.PolicyKit1: Timeout was reached (g-io-error-quark, 24)
Failed to start polkit.service: Connection timed out
See system logs and ‘systemctl status polkit.service’ for details.

Solution:-

yum reinstall polkit
OR
wget http://mirror.centos.org/centos/7/updates/x86_64/Packages/polkit-0.112-22.el7_7.1.x86_64.rpm
yum install polkit-0.112-22.el7_7.1.x86_64.rpm
It will install two other packages as well.
—> Package mozjs17.x86_64 0:17.0.0-20.el7 will be installed
—> Package polkit-pkla-compat.x86_64 0:0.1-4.el7 will be installed
Once installed, start service.
systemctl start polkit
systemctl status polkit
● polkit.service – Authorization Manager
Loaded: loaded (/usr/lib/systemd/system/polkit.service; static; vendor preset: enabled)
Active: active (running) since Sat 2019-11-16 09:20:53 EST; 4s ago
Docs: man:polkit(8)
Main PID: 8302 (polkitd)
CGroup: /system.slice/polkit.service
└─8302 /usr/lib/polkit-1/polkitd –no-debug