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Re: SMTP spoofing ?

  • From: Miquel van Smoorenburg
  • Date: Fri Feb 20 13:25:40 1998
  • Distribution: cistron
  • Newsgroups: lists.nanog

In article <[email protected]>,
John R Levine  <[email protected]> wrote:
>Are there any routers currently available that can do port 25 spoofing for
>dialup users?  That is, when the user attempts to connect to port 25
>anywhere, he in fact connects to port 25 on your own SMTP server instead. 

Cisco? Just setup a routemap with an access list that matches TCP port
25, and sets next-hop to a box that supports `transparent proxying'.
Linux does, and AFAIK the *BSD's can do it as well.

Some squid users are doing this with port 80 to redirect HTTP traffic
through the caching proxy - there's some docs for it on
in the FAQ, read the section about "transparent proxying".

However I think that policy routing is still process switched, and as
such can use a lot of CPU on the router.

 Miquel van Smoorenburg |  The dyslexic, agnostic, insomniac lay in his bed
    [email protected]  |  awake all night wondering if there is a doG