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SYN problem with new TCP/IP stack


After switching from the "old" TCP/IP stack to the "new" one,
we've run into a problem which is causing customers to
complain.  

Here's the scenario:

 1) Host opens TCP connection to eCos application.

 2) Somebody pushes the reset button on the host.

 3) The host reboots and attempts to open a TCP connection to
    the eCos application _using_the_same_source_port_ (and the 
    same destination port).[1]

4a) When the _old_ stack received a SYN for an already-open
    connection, it sent an ACK with the sequence number from
    the old connection.  The host saw this and sent a RST
    (which drops the connection), then attempted to re-open the
    connection (which succeeded).  All was good.

4b) When the _new_ stack receives a SYN for an already-open
    connection, it just ignores it.  So, after a timeout of a
    minute or so, the host sends it again.  Again it's ignored.
    This goes on for 10-15 minutes at which point the eCos
    stack times out the connection and closes it.  Only then
    can the host open a new connection.

Is this difference in behavior there for a reason?  Does the
RFC (or any other "spec") address the proper response when one
receives a SYN for an already-open connection?.  I presume the
behavior in the new TCP/IP stack wasn't put there just to break
our systems. :)

[1] IMO, it's sort of stupid to always start with the same
    source port, if you ask me -- you're just begging for
    problems like this.  But nobody ever accused Microsoft of
    being smart.  At least not when it comes to technical
    stuff.

Off to read RFCs...
    
-- 
Grant Edwards                   grante             Yow!  Does someone from
                                  at               PEORIA have a SHORTER
                               visi.com            ATTENTION span than me?


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