Page 1 of 1

Port 465 is working but TCP_OUT and TCP6_OUT do not exist

Posted: 17 May 2025, 13:25
by mikussikus
Hi,
Someone can be able to explain me why port 465 works on my CSF Firewall ? I don't have set this port in TCP_OUT and TCP6_OUT. When I use below command, it works.

openssl s_client -connect smtp.gmail.com:465

In CSF I found in Firewall Configuration these parameters but I don't know how they compare to TCP_OUT

SMTP_BLOCK = ON
SMTP_ALLOWLOCAL = ON
SMTP_PORTS = 25,465,587

Re: Port 465 is working but TCP_OUT and TCP6_OUT do not exist

Posted: 17 May 2025, 21:38
by Sergio
Remember that SMTP uses an OUT port to deliver emails, so, the command:
SMTP_PORTS = 25,465,587
means that SMPT can use those ports to send info (on this case emails), so, that is why port 465 is open.

Re: Port 465 is working but TCP_OUT and TCP6_OUT do not exist

Posted: 18 May 2025, 06:53
by mikussikus
Thank you for the explanation.