Two lines... That's all what is needed with the new TCP content inspection
system to stop half of the spams I got home. One of my major customers who
uses HAProxy a lot has sponsored the development of some preliminary content inspection which is
used to decide whether to forward a connection or not. The very first usage of this feature consists
in checking that only SSL is spoken on a connection. But most likely more protocols will come soon.
As a nice side effect, I could now add a delay before the HELO message of my SMTP server, and reject
all robots which talk first (forbidden). And since many spam bots have small timeout values, many of
them abort before the timeout is reached, resulting in my incoming spam rate dropping from about 300/hour
to "only" 150/hour. Those who keep up with the time out slow down due to limited resources. The small
addition simply consists in adding those two lines in the frontend :
” source...
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