On Tue, 9 Mar 1999, John E. Martin wrote: >>>In this attack, an SMTP server is probed for common names, presumably >>>so that spam can the be targeted at them. The attacking machine >>>connects and issues hundreds of RCPT TO: commands, searching a long >>>list of common user names (e.g. susan) for ones that don't cause >>>errors. It then compiles a list of target addresses to spam. >> >>This is a good reason for sendmail users to add the following to their .cf >>files: >> >> >>O PrivacyOptions=goaway >> >> >>This will prevent VRFY and EXPN commands from functioning at all and >>releasing correct addresses. >> The goaway option will also, if I'm not mistaken, also screwup anyone who does ETRN to collect mail. Fetchmail is one program that uses ETRN I believe. Keith
This archive was generated by hypermail 2b30 : Fri Apr 13 2001 - 14:38:35 PDT