TCP/IP: no SYN/ACK response from dedicated ‘OVH kimsufi’ server after client sending SYN for port 873 (rsyncd)

 From the client debian 9 (IP 2.2.2.2 for example) : Chain OUTPUT (policy ACCEPT) target prot opt source destination test rsync or telnet doesn’t access remote socket (*not dropped by kernel** ¹): # telnet 1.1.1.1 873 Trying 1.1.1.1… If I test another ports, like 80, 443 or ssh, all is working well ! tcptraceroute 1.1.1.1 873…

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How to add additional email validation rules by a python/perl script in Postfix?

In main.cf I have multiple restrictions, as usually: smtpd_NNN_restrictions = # ….. # ….. I want to be able to use an additional python/perl script in each section to make the final decision of whether or not reject or pass an email. Namely, even though, say this triggers an email to get rejected: reject_rbl_client bl.spamcop.net,…

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