Local YUM server installation and configuration – RHEL7

The Yellowdog Updater, Modified (yum) is an open-source command-line package-management utility for Linux operating systems using the RPM Package Manager. Though yum has a command-line interface, several other tools provide graphical user interfaces to yum functionality.    Basically we will YUM to resolve the dependencies automatically and install them, Using YUM repository you can lot […]

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BLACKLIST AND WHITELIST FOR ZIMBRA SPAM FILTER

BLACKLIST AND WHITELIST FOR ZIMBRA SPAM FILTER   gin to console as “root” user. Edit the amavisd config file /opt/zimbra/conf/amavisd.conf.in, Add 2 lines: read_hash(\%whitelist_sender, ‘/opt/zimbra/conf/whitelist’); read_hash(\%blacklist_sender, ‘/opt/zimbra/conf/blacklist’); Create the list files: #vi /opt/zimbra/conf/whitelist example.com EOT #vi /opt/zimbra/conf/blacklist spammer@example.com EOT Restart Service: #su – zimbra -c ‘zmamavisdctl restart’

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RHEL 7 Extras

RHEL 7 Extras Introduction of Docker Docker is an open source project that automates the deployment of applications inside Linux Containers, and provides the capability to package an application with its runtime dependencies into a container. Device Hotplug Removed While RHEL 5/6 has device hotplug support (udev rule that runs the ifup script for newly […]

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RHEL7 and 6 difference

Features RHEL 7 RHEL 6 Default File System XFS EXT4 Kernel Version 3.10.x-x kernel 2.6.x-x Kernel Kernel Code Name Maipo Santiago General Availability Date of First Major Release 2014-06-09 (Kernel Version 3.10.0-123) 2010-11-09 (Kernel Version 2.6.32-71) First Process systemd (process ID 1) init (process ID 1) Runlevel runlevels are called as “targets” as shown below: […]

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CentOS 7 / RHEL firewalld settings

CentOS 7 / RHEL firewalld settings CentOS 7 has adopted firelwalld by default over the previous iptables, which will require some new steps to configure your firewall: # new CentOS/RHEL 7 Firewall: (see https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/Security_Guide/sec-Using_Firewalls.html ) # create a new service e.g. for webmin: $ cat /etc/firewalld/services/webmin.xml Webmin Server admin service. Restrict access and do not […]

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convert a PFX to a seperate .key/.crt file

So after you installed OpenSSL you can start it from it’s Bin folder. I’d like to put OpenSSL\Bin in my path so I can start it from any folder. Fire up a command prompt and cd to the folder that contains your .pfx file. First type the first command to extract the private key: openssl […]

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OpenSSL command reference

OpenSSL command reference General OpenSSL commands commands to generate CSRs, Certificates, Private Keys and other tasks. Generate a new private key and matching certificate signing request (Unix) openssl req -out CSR.csr -pubkey -new -keyout privateKey.key Generate a new private key and matching certificate signing request (Windows) openssl req -out CSR.csr -pubkey -new -keyout privateKey.key -config […]

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Configuring automatic startup of Oracle Database under systemd on RHEL 7/OEL 7/CentOS 7

Configuring automatic startup of Oracle Database under systemd on RHEL 7/OEL 7/CentOS 7 There are several methods how to start Oracle Database automatically during/after OS boot. You can use Oracle CRS, other clusterware or init implemented in Linux. Starting RHEL 7 SysV init has been replaced by systemd or simply said systemd is the new […]

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IPMI

IPMI ( Intelligent Platform Management Interface ) : It is a remote hardware health monitoring and management system that defines interfaces for use in monitoring the physical health of servers. IPMI provides a way to monitor & manage a server system that may be powered off or unresponsive by using a network connection to the […]

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dynamic date value in shell scripts

dynamic date value in shell scripts using a variable – easier to read in scripts: NOW=$(date +”%Y%m%d%H%M%S”) echo “bar” > “$NOW”foobar.txt one-line, equivalent to above: echo “bar” > $(date +”%Y%m%d%H%M%S”)foobar.txt alternate single-line format: echo “bar” >> $(date “+myfile%Y%m%d.txt”) man strftime to see formatting values

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