Category Archives: Linux

HOWTO Virtual Mail Hosting on CentOS 6.x – Postfix MySQL Dovecot PostfixAdmin Amavisd-new Spamassassin Clamav DKIM SPF

Introduction This is an advanced email server configuration. This configuration will allow you to serve multiple domains on one server. This howto will allow you to setup a server that is one of four mail server types: Mail server with … Continue reading

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Forwarder zone

If you want a name server to forward queries for certain domain names to another name server, use a zone statement of type forward to tell a BIND server to forward queries for domain names that end in the specified suffix to particular … Continue reading

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Stub zones

Stub zones are a little like slave zones, in that the name server periodically checks with its master server to see if the zone’s serial number has changed. But instead of transferring the whole zone, it retrieves just the zone’s … Continue reading

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Linux tools

In order to get the list of sorted folders size with folder name on  level 1, I figured out a method which would be helpful all admins. du -h –max-depth=1 <<folder name>>| perl -e ‘sub h{%h=(K=>10,M=>20,G=>30);($n,$u)=shift=~/([0-9.]+)(\D)/; return $n*2**$h{$u}}print sort{h($b)<=>h($a)}<>;’ Note … Continue reading

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Editing users cronjob through ssh

I can see cronjobs owned by root by crontab -l You can use following command to see user’s crons crontab -u username -l User’s cron jobs reside in /var/spool/cron/ you can see them there also. You would have to run … Continue reading

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Check Port 25 with the Telnet Command

You can check your SMTP Server on SMTP port 25 with the following Telnet command: Open a command line and type telnet smtp-server.domain.com 25 If your server is online a connection will be established on port 25 (SMTP). An Exchange … Continue reading

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Deleting Linux Backup Easily With Rotation

Please create a cron job for the same and insert the following command. find /data/backup/ -type f -ctime +90 -exec rm -f {} \; -print find /data/backup/ -type d -ctime +90 -exec rm -rf {} \; -print To check out … Continue reading

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Set time in Linux

This document explains how to set your computer’s clock from Linux and how to set timezone. On Linux systems, you have a choice of keeping the hardware clock in UTC/GMT time or local time. How to Set timezone The timezone under … Continue reading

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