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Showing posts from October, 2019

Centos: Solving SSL connection error to EPEL repository

the old Centos version like 6.X is commonly have encounter following error message while connecting to epel repository:

Could not get metalink https://mirrors.fedoraproject.org/metalink?repo=epel-6&arch=x86_64 error was
14: problem making ssl connection


Postfix : Open New Instance With Filters

It's quite often our client is asking to add another server IP in trusted network list (a.k.a mynetworks) for sending email without any authentication, but sometime in the future it can be chaos since the application server possibly infected by malware that sending spam email outside. so then to prevent that we can instruct postfix to add instance that will be listen in port other than usually (port 25) and we enforce the rule to make sure it's originally email comes from legitimate sender, we can combine all filters together base on criteria such as by sender, headers, etc.
note: I'm using zimbra's postfix for these steps, you can adjust in your own local postfix's configuration. For the filter we will enforcing sender is notifikasi@sender.com, with subject that begin or must include with word Notifikasi.The allowed sender will be listed in a file, also we do the same for the header filters (Subject). The port will be listen on port 4545. Create the reference file …