I've had a private communication suggesting that the default SMTP banner
be changed. The reasons for wanting a change (security by obscurity and
saving resources) are, IMHO, totally spurious. However, the arrival of
Exim 4 does provide an opportunity for changing the default banner, and
it hasn't been considered since the very first release. The default
currently is:
smtp_banner = $primary_hostname ESMTP Exim $version_number \
#$compile_number $tod_full
I think I sort of copied it from Smail 3, but I can't remember for sure.
It is probably true that none of the information in the banner is ever
actually used by the client MTA. I suspect that even the ESMTP is no
longer relevant. (There was a time when ESMTP in the banner was used
informally to mean "I speak ESMTP" because some older MTAs, when sent an
EHLO command, crashed instead of rejecting it.)
Does anybody have any strong feelings about what the default banner
should be? (Any one site can of course change it, by setting
"smtp_banner".) It does seem silly to output the compile number and
date/time, now I come to think about it. Do any of these find favour?
smtp_banner = Exim ready
smtp_banner = Exim ESMTP server ready
smtp_banner = ESMTP server ready
smtp_banner = OK
smtp_banner = ESMTP session initiated
Or something else?
--
Philip Hazel University of Cambridge Computing Service,
ph10@??? Cambridge, England. Phone: +44 1223 334714.
