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 From:  Peter Curran <lists at closeconsultants dot com>
 To:  m0n0wall at lists dot m0n0 dot ch
 Subject:  SMTP redirection for wireless hotspot
 Date:  Tue, 9 Nov 2004 10:53:20 +0000
An interesting little project just completed.  The customer manages upmarket 
apartment blocks and provides Internet access via wireless to each apartment.  
I have supplied a m0n0-based 'access controller' using the captive portal 
with radius to manage access, firewalling and some traffic management.

The customer has a problem with some short-term tenants who need to access 
their home ISP mail accounts.  The problem is not reading mail, but sending 
it.  It seems that many ISP's reject relaying from 'foreign' addresses and do 
not offer a POP-before-SMTP type solution to allow their users to send email 
when on the move.

The solution is quite simple - I modified the captive portal rules 
configuration to insert a 'forward' to port 25 for all traffic to 
port 25.  This then runs to a small CLG that makes a new connection to the 
SMTP service of the ISP providing the DSL connection, and then transparently 
copies the data between the two TCP connections.

The solution is based around a simple proxy called tcppm that I found in the 
FreeBSD ports.

If anybody is interested I would be happy to provide the details.


Peter Curran

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