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Re: NMAP information about postfix
From: Linux Addict <linuxaddict7_at_nospam>Date: Tue Apr 20 2010 - 17:23:29 GMT
To: Postfix users <postfix-users@postfix.org>
On Mon, Apr 19, 2010 at 11:37 AM, Wietse Venema <wietse@porcupine.org>wrote:
> Gaby L:
> > Hi
> > I scan with my postfix server with NMap from other location.
> > The NMAP creats report smtp port open (It is OK) but apear Postfix smtpd
> and other information about MTA program.
> > I dont want to apear any information about my MTA server.
>
> To disclose no information, close the SMTP port.
>
> Seriously.
>
> Even when you change the smtpd_banner value to say "$myhostname
> ESMTP Sendmail" (this text MUST start with the hostname), the
> server's replies (especially error messages) still reveal that it's
> really Postfix.
>
> Wietse
>
Disclaimer :- It may violate some RFCs and possibly break the smtp system
itself.
[root@stick ~]# grep ^smtpd_banner /etc/postfix/main.cf
smtpd_banner = "unknown"
[root@stick ~]# telnet 0 25
Trying 0.0.0.0...
Connected to 0.
Escape character is '^]'.
220 "unknown"