On Tue, Apr 20, 2010 at 1:33 PM, Brian Evans - Postfix List < grkni...@scent-team.com> wrote:
> On 4/20/2010 1:23 PM, Linux Addict wrote: > > > > > > On Mon, Apr 19, 2010 at 11:37 AM, Wietse Venema <wie...@porcupine.org > > <mailto:wie...@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. > > > > [r...@stick ~]# grep ^smtpd_banner /etc/postfix/main.cf <http://main.cf> > > smtpd_banner = "unknown" > > > > [r...@stick ~]# telnet 0 25 > > Trying 0.0.0.0... > > Connected to 0. > > Escape character is '^]'. > > 220 "unknown" > > > > > > As Wietse mentioned, the above has no effect on determining the server > type. > > Just because the banner doesn't say Postfix, doesn't mean a > script/person couldn't figure it out from the response/error messages. > > True. seems nmap doesn't even check the banner, it does an EHLO and picks the mta from response code. 25/tcp open smtp Postfix smtpd postfix/smtpd[21190]: lost connection after EHLO from stick127.0.0.1]
