Trafic control

[Msb]

Hi I am interested in monitoring the traffic on some of the services on my
FreeBSD server.

Mail:

Qmail + courier imap as imap server.
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Any input on monitoring the SMTP, imap, and incomming mail traffic per user?

Web
Apache

Apache seems to log the requests made, but not the actual amount of bytes
transfered - eg. if i start downloading a 1 gig file an cancel immediatly it
will still show up as 1 gig in the log file.

Any inputs on how to do this?