"Za'mbori, Zolta'n" <zamboriz(_at_)axelero(_dot_)hu> wrote:
IMHO SMTP is a "move the message closer to the recipient mailbox"
protocol. On the SMTP level there are no such thing like one-time
one-way or two-way. (MTA is comparable to a router. And non-firewall
routers does not know about sessions.)
Of course. But the *intent* behind SMTP was to enable two-way human
communication. If the intent was to publish information only in one
direction, then the protocol would look very different.
e.g. UDP "notification" packets, containing URL's where the
information may be found.
The entire complexity of SMTP is there to support two-way
communication.
SMTP compared to other protocols is more attackable because there are no
rules assigned to email addresses while there are rules assigned to
ports. (For example nobody can use a DNS service as an NTP service.)
Ports are not protocols. Someone can easily run DNS on the port
assigned to NTP. This is a big problem for an IDS. If TCP had a
"protocol" field, in addition to "src/dst port" fields, then a number
of network problems, and application insecurities could have been
avoided.
Alan DeKok.
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