Problem connecting to my email with a Centos7 server - php

Question

I developed a simple code, with the php language, to connect to my email and count the number of emails received, using the local Window 10 server.
<?php
// server IMAP per la connessione
$server = "{imap.gmail.com:993/ssl/novalidate-cert}";
// account Gmail
$login = 'login#gmail.com';
// password per l'accesso a Gmail
$password = 'password';
// connessione IMAP ad un account Gmail
$connessione = imap_open($server, $login, $password);
$conteggio = imap_num_msg($connessione);
echo $conteggio."<br>";
By enabling the IMAP protocol on Gmail and enabling access to less secure apps, the code does
not give any kind of error.
The problem arises when I try to execute this code into a Centos 7 server machine.
I installed the IMAP protocol compatible with my PHP 7.3 version, using this command line: yum --enablerepo=centos-sclo-sclo-testing install sclo-php73-php-imapservice imapd restart.
Once the package is successfully downloaded, I restart the server machine and go check on
<?php
phpinfo();
?>
and notice that the IMAP is enabled.
imap
IMAP c-Client Version 2007f
SSL Support enabled
Kerberos Support enabled
After this check, if I try to run my initial code, this error message appears to me on output: warning: imap_open(): couldn’t open stream {imap.gmail.com:993/ssl/novalidate-cert} even though i have enabled imap and by actvaing.
PS. the password and login are correct.

Answer 1

The issue doesn't seem to be PHP related, but connection related, especially if the script works on a different machine.
There are two things you need to check.
Can you outbound connect on port 993 (is it open for OUT connections). You can try telnet to check that and if it doesn't work verify your Linux Firewall settings.
Do you have SELinux enabled and if you do did you check your audit log for AVC denials? It you have issues you may need to enable your httpd_can_network_connect or even do an audit2allow as the port might be non-standard. Be careful what you are doing as you can disrupt security on your server.