+------ Ralf Hildebrandt wrote (Thu, 10-Jun-2010, 23:31 +0200): | | I heard that there are firewalls/security appliances that supposedly | can distinguish "somebody using telnet" from "a machine speaking SMTP". | | I must admit, it sounds feasible (timing between keystrokes etc.), but | little useful. | | Anyway. Is there such a thing? Does anybody use such a thing?
ISTR someone doing (or speculating about) this with sendmail, perhaps 20 years ago, based on detecting telnet option negotiation. Never having used it, please forgive my fuzzy memory. It would be easy to compile a line mode telnet client without option negotiation that would defeat those two particular techniques, though it likely would appear to be rather slow. Best, Chuck
