[SOLVED] Why Port 25 is open on Debian 8.6?

hack3rcon · 12-04-2016, 08:09 AM

Hello.
I installed Debian 8.6 amd64 and when I Nmap my system then Nmap tell me that Port 25 is Open!!! If I disable this service can it cause any problem?

Thank you.

bathory · 12-04-2016, 01:06 PM

Quote:

Originally Posted by hack3rcon

Hello.
I installed Debian 8.6 amd64 and when I Nmap my system then Nmap tell me that Port 25 is Open!!! If I disable this service can it cause any problem?

Thank you.

Hi,

Post 25 is the default smtp port. If you don't want to use your box as a mail server, you can disable postix:

Code:

sudo service postfix stop;
sudo update-rc.d postfix disable;

Regards

hack3rcon · 12-05-2016, 01:10 AM

Quote:

Originally Posted by bathory

Hi,

Post 25 is the default smtp port. If you don't want to use your box as a mail server, you can disable postix:

Code:

sudo service postfix stop;
sudo update-rc.d postfix disable;

Regards

Thank you a lot.
I used "sudo systemctl disable postfix" can it enough? I don't like it start automatically at boot.

pan64 · 12-05-2016, 01:46 AM

you can simply check it by rebooting your box. Was that enough?

bathory · 12-05-2016, 03:19 AM

Quote:

Originally Posted by hack3rcon

Thank you a lot.
I used "sudo systemctl disable postfix" can it enough? I don't like it start automatically at boot.

If you're using systemd it should be enough.

Regards

hack3rcon · 12-05-2016, 06:49 AM

Quote:

Originally Posted by bathory

If you're using systemd it should be enough.

Regards

I did it but when I reboot my system then "Nmap" said me port 25 is open!!!
It is an output of "nc":

Code:

nc localhost -v 25
localhost [127.0.0.1] 25 (smtp) open
220 Xen-aka-X3n ESMTP Exim 4.84_2 Sun, 04 Dec 2016 16:17:42 -0800

Code:

sudo service postfix stop
[sudo] password for jason: 
Failed to stop postfix.service: Unit postfix.service not loaded.

bathory · 12-05-2016, 07:28 AM

Quote:

nc localhost -v 25
localhost [127.0.0.1] 25 (smtp) open
220 Xen-aka-X3n ESMTP Exim 4.84_2 Sun, 04 Dec 2016 16:17:42 -0800

sudo service postfix stop
[sudo] password for jason:
Failed to stop postfix.service: Unit postfix.service not loaded.

From the nc output looks like you're running exim and not postfix, so replace postfix with exim in the commands above

hack3rcon · 12-05-2016, 09:16 AM

Quote:

Originally Posted by bathory

From the nc output looks like you're running exim and not postfix, so replace postfix with exim in the commands above

I did:

Code:

sudo systemctl disable exim

And reboot my system but problem exist:

Code:

nc localhost -v 25
localhost [127.0.0.1] 25 (smtp) open
220 Xen-aka-X3n ESMTP Exim 4.84_2 Sun, 04 Dec 2016 18:42:14 -0800

bathory · 12-05-2016, 11:45 AM

Quote:

I did:

sudo systemctl disable exim

And reboot my system but problem exist:

Apparently the service is called exim4 nowadays, so use:

Code:

sudo systemctl disable exim4

sundialsvcs · 12-05-2016, 12:44 PM

Umm, it is a fairly simple matter to ps -A and look at the list of daemons and other processes that are running.

When you initially install your Linux system, you should first very carefully ponder exactly what daemons you actually wish to run. Sure, there are a handful of "canned choices," but you don't in fact need to choose any one of them.

Please(!) understand that I mean absolutely nothing personal when I observe:

Quote:

Your system's configuration must be, not an easy choice, but a conscious one!"

"Know what you run, and know why you run it!"

hack3rcon · 12-06-2016, 12:39 AM

Quote:

Originally Posted by bathory

Apparently the service is called exim4 nowadays, so use:

Code:

sudo systemctl disable exim4

Thank you. Problem solved.